Part 6: Managing Large-Scale Projects with Map Fusion

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Quick Field Guide

Scan Length & Project Splitting

LixelStudio Hard Limits:

• Max 10 scans per batch
• Max 200 minutes combined duration per batch
• Both limits must be satisfied simultaneously

Individual Scan Duration Guidelines:

• 10-20 minutes: Typical building interiors (good features)
• 25-30 minutes: Outdoor/feature-poor (monitor 200-min limit)
• 35 minutes max: Battery constraint (~90 min runtime)

Single Long vs. Multiple Short:

• Single Long: <30 data-preserve-html-node="true" min projects, continuous open areas
• Multiple Short: >30 min projects, multi-floor buildings, multi-operator

Segmentation Strategy:

• 5-10 scans per segment (leaves buffer under 10-scan limit)
• Follow natural divisions (floors, functional areas, buildings)
• 15-30m overlap between segments with rich features

Learn more about scan length planning →

RTK Workflow - Real-Time Kinematic

RTK Module Specifications:

• Standard RTK: 0.8cm + 1ppm horiz., 1.5cm + 1ppm vert.
• Survey RTK: Same accuracy, 5.5dBi antenna (vs 2.8dBi standard)
• Better for: partial canopy, urban canyons, long baselines >30km

RTK Account Configuration (LixelGO):

• Navigate to RTK Settings (satellite icon)
• Type: Custom (or Qianxun/China Mobile if in China)
• Host: Server address (e.g., rtk.provider.com)
• Port: 2101 (standard NTRIP)
• Mount Point: Station code from provider
• Username/Password: Account credentials
• Source Ellipsoid: WGS84 (verify with provider)

Pre-Scan RTK Verification:

• Red light: Power but no connection (check credentials/internet)
• Blue light: Float solution (wait 30-90 sec for convergence)
• Green light: Fixed solution (ready to scan)
• LixelGO status: Verify "Fixed", 10+ satellites, age <5 data-preserve-html-node="true" seconds

Active Monitoring During Scanning:

• Watch RTK light continuously
• Green = good, brief blue flickers = normal
• Extended blue/red = problem

RTK Loss Response Strategy:

• <30 data-preserve-html-node="true" sec, <30m data-preserve-html-node="true" travel: Continue normally (brief acceptable)
• >2 min, >100m travel: Significant degradation
  • Option A: Continue if interior tolerates lower accuracy
  • Option B: Pause scan, wait for RTK return
  • Option C: Stop scan, start new session for fusion

Minimum RTK Requirements:

• Trajectory length with RTK fixed: >10 meters
• Valid RTK points after filtering: >100 points
• For 3-5cm accuracy: RTK fixed >50% of duration
• Max non-fixed gaps: <100m data-preserve-html-node="true" (L2 Pro), <50m data-preserve-html-node="true" (K1)
• Total trajectory: >100m with turns/direction changes

RTK Processing (LixelStudio):

1. Check "GNSS (RTK)" in Coordinate Transformation
2. Click Settings → Review quality chart (should be mostly green)
3. Verify Source = WGS84, set Target coordinate system
4. Apply → Start processing

Learn more about RTK →

PPK Workflow - Post-Processed Kinematic

When to Use PPK Over RTK:

• ✅ No RTK network coverage
• ✅ Highest accuracy needed
• ✅ High RTK service costs
• ✅ Want flexibility to reprocess
• ❌ RTK network is good and reliable
• ❌ Need results quickly
• ❌ Don't have base station equipment

Required PPK Equipment:

• Survey-grade GNSS base station (Trimble R10, Leica GS18, etc.)
• Ability to determine precise base coordinates (<few data-preserve-html-node="true" cm)
• RINEX format converter (if base outputs proprietary format)
• Stable support (tripod over monument or stable ground)

Base Station Deployment:

• Location: Unobstructed sky view (10° elevation to zenith, 360°)
• Stability: Absolutely stationary throughout session
• Proximity: <5km data-preserve-html-node="true" ideal, <30 data-preserve-html-node="true"-50km max
• Timing: Start logging 5 min before scanning, end 5 min after
• Duration: Minimum 15 minutes (longer = better)

Base Coordinate Determination Methods:

1. Survey Monument: Occupy published monument (best)
2. PPP Services: 2-6 hour observation, submit to CSRS-PPP/OPUS (1-3cm)
3. CORS Network: 30-60 min observation, process vs. CORS (0.5-2cm)
4. Autonomous GPS: 10-15 min (1-3m accuracy - only if relaxed requirements)

Rover Configuration (LixelGO):

• Settings → GNSS Settings → Change "RTK" to "PPK"
• Enable GPS, GLONASS, BeiDou, Galileo (match base station)
• Ignore RTK light color during scanning (red/blue = normal for PPK)
• No status verification needed (key advantage of PPK)

PPK Processing (LixelStudio):

1. Check "GNSS (PPK)" in Coordinate Transformation
2. Click Settings → Import Observation File (.25O) + Navigation Files (.25P/G/C/E)
3. Verify observation time span covers rover scan + margins
4. Enter base station coordinates (format: WGS84 BLH or XYZ)
5. Enter antenna height (meters, specify reference point)
6. Set elevation mask (15° default), processing mode = Kinematic
7. Calculate → Review trajectory (should be mostly green = fixed)
8. If mostly green, configure target coordinates → Apply → Start

PPK Trajectory Quality:

• Green segments: Fixed ambiguity, cm-level accuracy
• Yellow/orange: Float solution, dm-level accuracy
• Red: Poor/no solution
• Target: >70% green (>95% ideal)

Learn more about PPK →

GCP Workflow - Ground Control Points

When to Use GCP:

• GPS-denied environments (indoors, under heavy canopy)
• Highest accuracy requirements (1-2cm possible)
• RTK unavailable or unreliable
• Heritage documentation, as-built verification

Control Point Spacing:

• L2 Pro: <100m data-preserve-html-node="true" (optimal 50-70m)
• K1: <50m data-preserve-html-node="true" (optimal 30-40m)
• Minimum 3 points (4+ recommended)
• Geometric distribution: NOT on straight line

Surveying Requirements:

• RTK GPS: 1-2cm horiz., 2-3cm vert. (2-5 min occupation)
• Total Station: 2-5mm (with proper network adjustment)
• Static GPS: 0.5-1cm (1-2 hour observation, CORS network)
• ❌ Handheld GPS (3-10m), smartphone GPS (5-15m), tape measure

Physical Markers:

• ✅ XGRIDS reflective targets + steel base
• ✅ Survey nails with washers in concrete
• ✅ Painted crosshairs (durable paint/epoxy)
• ✅ Existing durable features (precise centers only)
• ❌ Paper/cardboard, painted marks on loose surfaces

Control Point Coordinate File (CSV):

Point Name,Easting,Northing,Height
CP01,451234.567,4321098.765,123.456
CP02,451334.567,4321098.765,123.890

• Header exactly: "Point Name,Easting,Northing,Height"
• Names: English letters/numbers only, no spaces
• Coordinates: In desired output system (UTM, State Plane, etc.)
• Precision: 3-4 decimal places (mm precision)
• Save as: CSV (comma delimited), NOT .xlsx

Field Control Point Marking Procedure:

1. Slow to 0.3-0.5 m/s when within 5m of point
2. Stop adjacent to marker
3. Align steel base corner exactly with marker center (verify from above)
4. Lower scanner onto base smoothly
5. Open Control Point Mode in LixelGO (CP icon)
6. Tap "+", enter point name EXACTLY as in CSV file (case-sensitive)
7. Tap OK (scanner flashes green ~1 sec)
8. Wait motionless 5 seconds after confirmation
9. Lift slowly, walk 1-2 complete circles around point (2-3m radius)
10. Continue to next control point

GCP Processing (LixelStudio):

1. Check "Control Point" in Coordinate Transformation
2. Click import button → Select CSV file
3. Click "Control Point Editing" → Verify automatic matching
4. Use 70-80% for transformation, 20-30% as check points
5. Uncheck boxes for check points (reserved for verification)
6. Click "Check" → Review visualization for major errors
7. If good, click "Confirm" → Start processing

GCP Quality Indicators:

• Good residuals: 1-3cm at control points
• Concerning: >5cm residuals (check surveying/scanning)
• Check points: Should match control point residuals
• If check >> control by 2-3×, network may be inadequate

Common GCP Errors:

• Name mismatch: "CP01" ≠ "cp01" ≠ "CP 01" (case/space sensitive)
• Insufficient coverage: Not circling point (5 sec dwell + 1-2 circles)
• Poor alignment: Base corner offset 1-2cm from marker
• Wrong base: Using tripod instead of steel control point base
• File format: XLSX not CSV, wrong header, blank lines

Learn more about GCP →

Measurement Point Workflow (L2 Pro Only)

Concept:

• Mark indoor points that inherit outdoor RTK accuracy via SLAM-RTK fusion
• Requires: Firmware 2.3+, good RTK outdoors first
• Max distance from RTK: 100m (accuracy degrades with distance)

Accuracy Degradation:

• Within 50m: ~5cm horizontal/vertical RMSE
• Within 100m: ~10cm horizontal/vertical RMSE
• Beyond 100m: >10cm RMSE

Field Procedure:

1. Establish RTK fixed outdoors (green light)
2. Walk L-shaped path (10m × 10m) with RTK for geometric diversity
3. Scan around building exterior with RTK
4. Note location where RTK lost (entry point)
5. Enter building/GPS-denied area
6. Mark measurement points at desired locations (Tools → Add Measurement Point)
7. Name descriptively ("Building Corner NW", "Equipment Center")
8. Return to outdoor RTK area if possible (creates loop)

Post-Processing:

• Download "measure_points_latest.csv" from project/measurepoint/ folder
• Contains: Point Name, Easting, Northing, Height, Timestamp, Accuracy Estimate
• Accuracy Estimate >15cm = use cautiously

Learn more about measurement points →

Hybrid Workflows

RTK Primary + GCP Verification:

• Survey 3-5 control points across site (100-200m spacing)
• Scan with RTK, mark control points when passing
• Processing: Enable both RTK and GCP
• Use 1-2 GCP for transformation, rest as check points
• Benefit: Verify RTK accuracy, catch systematic errors

GCP Indoors + RTK Outdoors:

• Place control points at transition zones (doorways, entrances)
• Scan outdoor with RTK, mark transition points before entering
• Continue indoor (RTK lost), mark indoor control points
• Exit at transition, mark exit points (RTK returns)
• Processing: Enable both RTK and GCP
• Benefit: Complete coverage of mixed indoor-outdoor sites

RTK + Periodic Control Points (Large Projects):

• Establish control points at major locations (200-300m spacing)
• Daily scanning uses RTK, mark nearby control points opportunistically
• Each control point marked multiple times across different sessions
• Processing: RTK primary, control points as check points
• Benefit: Robustness against RTK failures, continuous accuracy monitoring

Learn more about hybrid workflows →

Data Transfer

USB Transfer (Fastest):

1. Scanner in standby (solid green)
2. Press power button once, wait 3 sec, press again (enters USB mode = solid blue)
3. Connect USB 3.0 cable to computer
4. Computer recognizes as removable drive (5-10 sec)
5. Navigate to /model directory
6. Copy project folders to computer
7. USB 3.0 speed: ~100-200 MB/s (10GB = 50-100 sec)
8. Verify transferred folder size matches original
9. Windows: Right-click drive → Eject
10. After disconnect, press power button once (returns to standby = solid green)

Storage Management:

• 1TB internal SSD: ~20-30 hours of scanning
• Free space target: >50GB before starting new work
• After transfer + backup confirmation, delete old projects from scanner
• Maintain 100+ GB free for safety margin

Camera Coloring Decisions

Enable Camera Coloring When:

• Deliverables need visualization (client presentations)
• Even illumination without extreme contrast
• Overnight processing time acceptable
• Storage adequate (30-40% larger files)

Disable Camera Coloring When:

• Deliverables are measurements only
• Extreme lighting (bright sun + deep shadows, very dark)
• Quick processing needed
• Limited storage

Configuration:

• Must be enabled during scanning (can't add retroactively)
• LixelGO: Settings → Camera → Built-in Camera toggle
• Test 15-30 sec scan to verify before main scan

Learn more about camera coloring →

Processing Quick Reference

Basic Single-Scan Processing:

1. LixelStudio → Project Processing → Import Project
2. Select transferred project folder → Open
3. Coordinate Transformation: Check method (None/RTK/PPK/GCP)
4. Camera Coloring: Built-in Camera Coloring (if used during scan)
5. Advanced Settings: Leave defaults for first attempt
6. Start → Monitor progress (SLAM optimization = 60-70% of time)
7. Output: Result subfolder → .las or .laz file

Processing Time:

• ~20-30× scan duration (10-min scan = 120-180 min on recommended hardware)

Learn more about processing →

Processing Failures Quick Fix

LIO Trajectory Drift Error:

1. Strategy 1: Advanced Settings → Special SLAM Mode → "Robust Mode"
2. Strategy 2: SLAM Mapping End Time Selection → process only first portion
3. Strategy 3: Debug Options → "Start-to-End Loop Closure" (if loop formed)
4. Strategy 4: Special SLAM Mode → "Narrow Scene" (tunnels/corridors only)
5. Strategy 5: Contact XGRIDS support to split scan

Memory Exhausted Errors:

1. Close other applications
2. Advanced Settings → Enable Low-Memory Reconstruction
3. Reduce scan duration being processed
4. Disable Point Cloud Enhancement
5. Upgrade RAM from 64GB to 128GB

Coordinate Transformation Errors:

• Control point matching: verify names match exactly (case/space sensitive)
• RTK: verify Source Ellipsoid matches provider output
• Datum: verify transformation parameters correct
• Disk space: free disk space (requires 2-3× raw scan size)

Learn more about troubleshooting →

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Full Explanatory Guide

Scan Length Guidelines and Project Splitting Strategy

Before beginning data collection, understanding scan duration limits and project segmentation strategy prevents processing failures and enables efficient large-scale project execution. The planning decisions made before scanning directly determine whether processing succeeds and how much effort fusion requires.

Understanding Processing Limits

LixelStudio imposes two hard limits on project processing that cannot be exceeded:

The 10-scan batch limit allows processing a maximum of 10 individual scan files in a single processing operation.

The 200-minute combined duration limit restricts the total capture time across all scans in a batch to 200 minutes maximum.

These limits exist due to computational complexity and memory constraints. The SLAM optimization algorithm must simultaneously consider all scans in a batch, requiring RAM and processing power that scales with scan quantity and duration. Attempting to process beyond these limits causes the software to reject the batch with an error message before processing begins.

The interaction between these two limits creates practical planning constraints:

• A project with 10 scans averaging 15 minutes each totals 150 minutes (✅ within both limits)
• A project with 8 scans averaging 28 minutes each totals 224 minutes (❌ exceeds duration limit despite being under scan count limit)

Both limits must be satisfied simultaneously.

Individual Scan Duration Recommendations

Typical building interiors with good feature density: Individual scans should target 10-20 minutes duration. This provides adequate coverage while staying well below processing limits and fitting within a single battery charge.

Outdoor sites or feature-poor environments: Individual scans may extend to 25-30 minutes to ensure sufficient point density and loop closures, but this longer duration requires careful monitoring of the 200-minute cumulative limit.

Maximum practical scan duration: 35 minutes represents the safe maximum considering battery life (~90 minutes total runtime allows for initialization, multiple scans, and safety margin).

Single Long Scan vs. Multiple Short Scans

Use single long scan when:

• Project can be completed in <30 data-preserve-html-node="true" minutes total
• Scanning continuous open area without natural break points
• Simplicity is priority and processing limits won't be exceeded

Use multiple short scans when:

• Project exceeds 30 minutes total duration
• Scanning multi-floor buildings or multiple buildings
• Multiple operators working simultaneously
• Natural break points exist (floors, functional areas, buildings)
• Project requires flexibility in processing order

Project Segmentation Strategy

When projects require more than 10 scans or 200 minutes total duration, divide into segments for independent processing and later fusion.

Segment planning:

• 5-10 scans per segment (leaves buffer under the 10-scan limit)
• Follow natural divisions (floors, functional areas, separate buildings)
• 15-30 meter overlap between adjacent segments
• Overlap zones must have rich geometric features (not blank walls or empty spaces)

Control point strategy for multi-segment projects:

• Place shared control points in overlap zones
• Central segments need control points from all adjacent segments
• Creates control network tying segments together
• Enables accurate fusion in downstream processing

RTK Workflow - Real-Time Kinematic

RTK provides real-time absolute positioning during scanning by receiving corrections from a base station or NTRIP service. Understanding RTK workflow requirements, limitations, and monitoring procedures ensures successful georeferencing.

RTK Hardware Options

Standard RTK Module provides 0.8cm + 1ppm horizontal accuracy and 1.5cm + 1ppm vertical accuracy. The module features a 2.8dBi antenna suitable for most outdoor applications with good sky visibility.

Survey RTK Module provides the same accuracy specifications but features a 5.5dBi antenna with higher gain. This enhanced antenna performs better in challenging conditions including partial tree canopy, urban canyons with some sky obstruction, and long baseline distances exceeding 30km from base station.

The accuracy specification "0.8cm + 1ppm" means the base error is 0.8cm plus 1 part per million of the distance from the base station. For a project 10km from the base station: 0.8cm + (10km × 1ppm) = 0.8cm + 1cm = 1.8cm horizontal accuracy.

RTK Account Configuration

Configuring RTK account credentials in LixelGO enables the scanner to connect to the correction service.

Navigate to RTK Settings in LixelGO (the satellite icon in the main menu). The RTK Settings screen displays fields for RTK Type, Host, Port, Mount Point, Username, Password, and Source Ellipsoid.

RTK Type selection:

• For users in mainland China using Qianxun SI or China Mobile RTK services, select the appropriate service from the dropdown (simplified configuration requiring only username and password)
• For all other RTK services worldwide, select "Custom" to enable manual entry of all connection parameters

Host field: Enter the server address exactly as provided by the RTK service (typically "rtk.provider.com" or "192.168.1.100"). Do not add "http://" or other protocol prefixes.

Port field: Enter "2101" (standard NTRIP port) unless the RTK provider specifically indicates a different port.

Mount Point field: Enter the specific reference station or virtual reference station code (typically a short code like "VRS_3_1" or "BASE_NYC") as provided by the RTK service.

Username and Password: Enter account credentials exactly as provided. Passwords are case-sensitive.

Source Ellipsoid: This setting is critical and must match the coordinate system that the RTK provider outputs. Most international commercial RTK services output WGS84 coordinates. Some regional providers, particularly in China, may output CGCS2000 coordinates. If uncertain, contact the RTK provider and explicitly ask "What coordinate system and datum do your RTK corrections output?"

Getting the Source Ellipsoid setting wrong causes coordinate transformation failures during processing even if RTK connectivity works correctly during scanning.

Saving configurations: After entering all connection parameters, tap "Save" at the bottom of the RTK Settings screen. Enter a descriptive name for the configuration such as "Project Site A" or "VRS Northeast Region". Saved configurations appear in a dropdown menu for quick selection in future scanning sessions.

Pre-Scan RTK Verification

Before beginning scanning with RTK, verification that RTK is functioning correctly prevents discovering problems after completing the scan when it is too late to correct them.

Power on the scanner and wait for the boot sequence to complete (solid green indicator light). Observe the RTK module indicator light as it progresses through states:

Red RTK light indicates the module has power but is not connected to the RTK service. Causes include:

• Incorrect account credentials (wrong username, password, host, port, or mount point)
• No internet connection available (verify mobile device has cellular data or WiFi)
• RTK service is offline or experiencing outage
• RTK account has expired or exceeded usage limits

Blue RTK light indicates the module is connected to the RTK service and receiving correction data but has not yet achieved fixed solution. Blue state represents float solution where positioning accuracy is better than standalone GNSS (approximately 0.3-1 meter horizontal) but has not yet converged to centimeter-level fixed solution. Float solution is normal immediately after connection and usually resolves to fixed solution within 30-90 seconds if conditions are adequate.

Green RTK light indicates fixed solution has been achieved with centimeter-level positioning accuracy. Green confirms that RTK is functioning correctly and the scanner is ready to begin scanning with RTK georeferencing.

Verification in LixelGO provides additional detail beyond the indicator light. Open RTK Settings and observe the real-time status information:

• Solution Type: Should display "Fixed" when ready to scan
• Satellite Count: Should display 10 or more satellites for robust positioning
• Age of Differential: Should display less than 5 seconds indicating corrections are current

If the RTK module indicator shows green but LixelGO shows something other than Fixed solution, trust the LixelGO displayed status over the indicator light. Do not begin scanning until LixelGO confirms Fixed solution.

Troubleshooting when fixed solution cannot be achieved:

1. Verify sky view: Check whether the scanner has unobstructed view of the sky from approximately 15 degrees elevation to zenith. Walk to a more open location away from trees, buildings, and overhead obstructions.

2. Check satellite count: In LixelGO RTK status, fewer than 8 satellites indicates marginal location. Fewer than 5 satellites makes fixed solution nearly impossible. Move to a location with better sky view.

3. Verify RTK account status: Log into the provider's account management website to confirm the account is active, payments are current, and usage limits have not been exceeded.

4. Verify Source Ellipsoid setting matches the provider's output coordinate system.

5. Wait patiently: The RTK module sometimes requires 2-5 minutes after power-on to download ephemeris data and achieve initial fix, particularly if the scanner has been powered off for an extended period or moved to a new location.

If troubleshooting does not resolve the issue within 10 minutes, contact the RTK provider technical support.

Scanning with RTK Active Monitoring

Once green indicator light and Fixed solution status in LixelGO confirm RTK is ready, execute the normal initialization procedure. The critical difference when scanning with RTK is continuous monitoring of the RTK indicator light throughout the scan session.

RTK status during scanning:

• Light should remain solid green throughout majority of scan when operating in open areas with good sky view
• Occasional brief flickers to blue during momentary signal interruptions (walking past a vehicle, under a small tree branch) are normal and do not require action
• Extended periods of blue or red light indicate problems requiring response

Common causes of RTK loss during scanning:

• Satellite obstruction (buildings, heavy tree canopy, tunnels, indoor areas)
• Electromagnetic interference (near power lines, industrial equipment, broadcast transmitters)
• Service interruption (internet connection drops, base station stops broadcasting)

When RTK light changes from green to blue or red, the scanner continues operating and recording data using pure SLAM without RTK positioning. The SLAM algorithm maintains relative accuracy within the scan using LiDAR and IMU data. However, absolute positioning accuracy degrades during periods without RTK.

Short RTK interruptions (under 30 seconds, less than 30 meters travel distance) can typically be bridged by SLAM with minimal accuracy impact. When RTK returns (green light), position jumps back to RTK-constrained accuracy.

Extended RTK interruptions (over 2 minutes, over 100 meters travel distance for L2 Pro or over 50 meters for K1) cause significant absolute positioning degradation. While the scan remains usable, portions scanned without RTK will have lower absolute accuracy.

Operator response strategy when losing RTK:

Strategy 1 for brief outages in transition areas (walking under doorway overhang, passing between vehicles): Continue scanning at normal pace. Monitor RTK light and confirm it returns to green within 20-30 seconds. These brief interruptions are acceptable.

Strategy 2 for extended outage entering buildings: Three options:

• Option A: Continue scanning if project tolerates accuracy degradation in interior areas not covered by RTK (suits projects where outdoor areas require high absolute accuracy but indoor areas only require relative accuracy)
• Option B: Pause scanning by stopping the scan, waiting to see if RTK returns upon exiting the building, then resuming when back in RTK coverage
• Option C: Stop this scan and start a new scan session, planning to fuse the two sessions together during processing (suits projects where both outdoor and indoor areas require georeferencing)

Strategy 3 for RTK recovery when exiting buildings or moving back to open sky: Watch for RTK light to change from blue or red back to green. This transition indicates fixed solution has been reacquired. Once green, absolute positioning accuracy resumes.

Minimum RTK Requirements for Processing Success

For LixelStudio to successfully use RTK data during processing, certain minimum conditions must be satisfied:

Trajectory length with RTK fixed must exceed 10 meters. The scanner must move at least 10 meters while maintaining RTK fixed solution. Simply initializing with RTK and standing still does not satisfy this requirement.

Valid RTK data points after processing must exceed 100 points. During processing, LixelStudio applies quality filters to raw RTK data. Low-quality RTK positions are rejected. For successful processing, at least 100 high-quality RTK positions must remain after filtering. This typically corresponds to approximately 30-60 seconds of scanning with good fixed solution.

For achieving the specified 3-5 centimeter horizontal RMSE accuracy with RTK:

• RTK should maintain fixed solution throughout the majority (over 50%) of scan duration
• Each continuous non-fixed section should not exceed 100 meters for L2 Pro or 50 meters for K1
• Total scan trajectory length should exceed 100 meters even if RTK is fixed throughout
• Scan route should include turns and direction changes rather than being a straight line

The SLAM algorithm needs trajectory variation including turns, elevation changes, and loops to separate RTK errors from SLAM errors. Straight-line trajectories do not provide sufficient geometric constraint for robust optimization.

RTK Processing Configuration in LixelStudio

After transferring scan data to the computer, RTK processing configuration enables the software to use the recorded RTK data for georeferencing.

Open the project in LixelStudio by navigating to Project Processing and selecting the project folder. In the Coordinate Transformation section, check the checkbox labeled "GNSS (RTK)". This enables RTK coordinate transformation and activates the Settings button.

Click "Settings" to open the RTK configuration dialog. The dialog displays a chart showing RTK data quality throughout the scan session:

• Horizontal axis: Time from scan start to scan end
• Vertical axis: RTK status
• Green bars: Periods where valid RTK data with fixed solution was recorded
• Yellow bars: Float solution periods
• Red bars: No RTK data or poor quality data that will be rejected

Ideally, the chart should display primarily green bars with minimal red or yellow sections. If the chart shows extensive red areas (more than 50% of scan duration), RTK data quality is insufficient for reliable georeferencing.

Source coordinate system should match the RTK provider output (usually WGS84). This must match the Source Ellipsoid setting used in LixelGO during scanning.

Target coordinate system should be configured for the desired output coordinates. Use the EPSG code search feature or manual parameter entry (see Part 3 for detailed coordinate system configuration guidance).

After verifying settings, click Apply and start processing. The software performs joint SLAM-RTK optimization, using RTK data to constrain the SLAM solution and achieve absolute positioning accuracy.

PPK Workflow - Post-Processed Kinematic

PPK (Post-Processed Kinematic) records GNSS observations during scanning and processes them afterward with base station data. This method tolerates temporary satellite blockage better than RTK because post-processing can resolve ambiguities that real-time processing cannot.

When to Choose PPK Over RTK

Use PPK when:

• No RTK network coverage is available in the project area
• Highest accuracy is needed (PPK can achieve slightly better results than RTK through more sophisticated processing algorithms)
• RTK service costs are prohibitive for the project
• Flexibility to reprocess with different base station data is desired

Use RTK when:

• RTK network coverage is good and reliable
• Results are needed quickly (RTK provides immediate georeferencing without post-processing delay)
• Base station equipment is not available or deploying it is impractical

Required PPK Equipment

Survey-grade GNSS base station capable of logging raw observations in RINEX format. Common options include Trimble R10, Leica GS18, Topcon HiPer, and Hemisphere Atlas systems.

Base coordinate determination capability: The base station position must be determined with precision better than a few centimeters. This requires either occupying a known survey monument, conducting a long static observation for PPP processing, or processing against a CORS network.

RINEX format converter (if base station outputs proprietary format): Some base station receivers output data in manufacturer-specific formats that must be converted to standard RINEX format before LixelStudio can process them.

Stable support: Tripod over survey monument or stable ground point that will not move during the observation session.

Base Station Deployment Requirements

Location selection: The base station requires unobstructed sky view from approximately 10 degrees elevation to zenith in all directions (360 degrees). Nearby buildings, trees, or terrain features that obstruct satellite visibility degrade base station data quality.

Stability requirements: The base station must remain absolutely stationary throughout the observation session. Any movement corrupts the base position reference and propagates errors to all rover positions computed relative to it.

Proximity to rover: Optimal distance is under 5 kilometers. Maximum recommended distance is 30-50 kilometers. Longer baselines increase atmospheric decorrelation effects and reduce fix rate during processing.

Timing: Start base station logging at least 5 minutes before beginning rover scanning. Continue base station logging until at least 5 minutes after rover scanning completes. This ensures complete temporal overlap.

Duration: Minimum 15 minutes base station observation even if rover scanning is shorter. Longer base station observations improve position determination accuracy and provide more satellite ephemeris data.

Base Station Coordinate Determination Methods

Method 1: Survey Monument (most accurate): Occupy a published survey monument with known coordinates. Set up the base station tripod over the monument using optical plummet. Measure antenna height from monument mark to antenna phase center. This method provides immediate accurate coordinates but requires monument availability.

Method 2: PPP Services (1-3cm accuracy): Conduct 2-6 hour static observation at the base location. Submit the observation file to a Precise Point Positioning service such as CSRS-PPP (Canada) or OPUS (United States). The service processes observations using precise satellite orbit and clock data to determine position. Results typically achieve 1-3cm accuracy but require substantial observation time.

Method 3: CORS Network (0.5-2cm accuracy): Conduct 30-60 minute static observation at the base location. Process the observation against nearby CORS (Continuously Operating Reference Station) network stations using baseline processing software. This method provides excellent accuracy with moderate observation time but requires proximity to CORS network.

Method 4: Autonomous GPS (1-3m accuracy): Record autonomous (non-differential) GPS position for 10-15 minutes and average the results. This method only achieves 1-3 meter accuracy and should only be used when project requirements are relaxed or when other methods are not feasible.

Rover Configuration for PPK

In LixelGO, navigate to Settings → GNSS Settings. Change the mode from "RTK" to "PPK". Enable all available satellite constellations (GPS, GLONASS, BeiDou, Galileo) that match the base station capabilities.

Critical difference from RTK: When scanning in PPK mode, the RTK indicator light will show red or blue during scanning. This is normal and expected. PPK does not require real-time corrections, so the lack of fixed solution indicator during scanning is not a problem.

No status verification is needed before or during scanning when using PPK mode. This represents a key advantage of PPK—the operator does not need to monitor fix status or worry about correction signal availability during data collection.

PPK Processing in LixelStudio

After transferring scan data to computer, PPK processing requires importing base station observation files and configuring base position.

In LixelStudio Project Processing, check "GNSS (PPK)" in the Coordinate Transformation section. Click Settings to open the PPK configuration dialog.

Import observation files:

• Click Import and select the base station observation file (.25O extension for observation data)
• Import navigation files (.25P for GPS, .25G for GLONASS, .25C for BeiDou, .25E for Galileo)

Verify that the observation time span shown in the software covers the rover scan time plus margins. If the base station stopped logging before rover scanning completed, PPK processing will fail for the uncovered time period.

Enter base station coordinates in either WGS84 geographic format (Latitude, Longitude, Height) or WGS84 geocentric format (X, Y, Z). The coordinate format must match the coordinate determination method used.

Enter antenna height in meters, carefully specifying which reference point (bottom of antenna, phase center, etc.) the height is measured to. Incorrect antenna height introduces systematic height errors in all rover positions.

Set elevation mask (default 15 degrees) to reject satellites too close to horizon where atmospheric effects are strongest and signal quality is poorest.

Set processing mode to "Kinematic" for rover moving during observation.

Click "Calculate" to run the PPK processing. The software performs differential processing between base and rover observations to compute precise rover trajectory.

Review trajectory quality in the trajectory viewer:

• Green segments: Fixed ambiguity solution with cm-level accuracy
• Yellow/orange segments: Float solution with dm-level accuracy
• Red segments: Poor solution or no solution

Target trajectory quality is >70% green (>95% ideal). If substantial portions remain yellow or red, consider:

• Checking base station data quality and time overlap
• Verifying base station coordinates are accurate
• Adjusting elevation mask or other processing parameters
• Accepting lower accuracy in problematic sections or rescanning

If trajectory quality is acceptable, configure target coordinate system and proceed with processing. The software applies the PPK solution to georeference the point cloud.

GCP Workflow - Ground Control Points

GCP (Ground Control Point) workflow uses surveyed markers placed throughout the scan area. During scanning, the operator marks these points. Processing software aligns the scan to control point coordinates through optimization.

When to Use GCP

GCP is required for:

• GPS-denied environments (indoors, underground, under heavy tree canopy)
• Highest accuracy requirements (1-2cm RMSE achievable with proper execution)
• Projects where RTK is unavailable or unreliable
• Heritage documentation requiring maximum accuracy
• As-built verification against tight tolerances

GCP is preferred over RTK when:

• Control point network can be established cost-effectively
• Multiple scan sessions will reuse the same control points
• Independent accuracy verification is required
• Project requires documentation that georeferencing meets specifications

Control Point Distribution Requirements

Spacing recommendations:

• L2 Pro: Maximum 100m spacing (optimal 50-70m for best accuracy)
• K1: Maximum 50m spacing (optimal 30-40m)

Minimum quantity: At least 3 points required for transformation (4+ strongly recommended). More points improve accuracy and provide redundancy.

Geometric distribution: Control points must NOT be arranged in a straight line. Points should surround the scan area in three-dimensional distribution (including elevation variation when applicable). Linear or planar arrangements provide poor geometric constraint and degrade transformation accuracy.

Coverage principle: Control points should encompass the entire scan area rather than clustering in one section. Gaps in control point coverage allow SLAM drift to accumulate unconstrained.

Control Point Surveying Requirements

Survey accuracy directly determines maximum achievable point cloud accuracy. The control point survey must be more accurate than the target point cloud accuracy.

RTK GPS provides 1-2cm horizontal and 2-3cm vertical accuracy with proper technique:

• Occupy each point for 2-5 minutes
• Verify fixed solution throughout occupation
• Use bipod or pole level to ensure vertical rod
• Measure antenna height carefully

Total Station provides 2-5mm accuracy with proper network adjustment:

• Use closed traverse or network configuration
• Include sufficient redundant observations for adjustment
• Perform least-squares network adjustment
• Document residuals to verify survey quality

Static GPS provides 0.5-1cm accuracy:

• Observe each point for 1-2 hours
• Process against CORS network or known monuments
• Use precise ephemeris and apply tropospheric modeling

Unacceptable survey methods:

• ❌ Handheld GPS (3-10m accuracy)
• ❌ Smartphone GPS (5-15m accuracy)
• ❌ Tape measure from uncertified reference points

Physical Marker Selection and Installation

Recommended markers:

• ✅ XGRIDS reflective targets with steel control point base (optimal for Lixel system)
• ✅ Survey nails with metal washers driven in concrete (permanent, precise)
• ✅ Painted crosshairs using durable paint or epoxy (visible, precise center)
• ✅ Existing durable features with precise centers (building corners, monuments)

Markers to avoid:

• ❌ Paper or cardboard (not durable, moves easily)
• ❌ Paint on loose or flexible surfaces (paint chips off, surface moves)
• ❌ Features without clear precise centers (vague reference points)

Markers must remain stable throughout scanning. Check that markers are firmly attached before beginning scan session.

Control Point Coordinate File Format

LixelStudio requires control point coordinates in specific CSV format:

Point Name,Easting,Northing,Height
CP01,451234.567,4321098.765,123.456
CP02,451334.567,4321098.765,123.890
CP03,451284.567,4321148.765,124.123

Format requirements:

• Header line exactly: "Point Name,Easting,Northing,Height" (must match this exactly including capitalization and commas)
• Point names: English letters and numbers only, no spaces or special characters (spaces break the format)
• Coordinate system: Coordinates must be in the desired output coordinate system (UTM, State Plane, etc.), not latitude/longitude
• Coordinate precision: Use 3-4 decimal places to preserve millimeter precision
• File format: Save as CSV (comma delimited), NOT .xlsx or other spreadsheet formats

Common file format errors:

• Using .xlsx instead of .csv (LixelStudio cannot read Excel files)
• Wrong header text or column order
• Blank lines in the file
• Spaces in point names
• Missing or extra commas

Field Control Point Marking Procedure

During scanning, when approaching a control point:

1. Slow down to 0.3-0.5 m/s when within 5 meters of the control point

2. Stop adjacent to the marker (within 1 meter)

3. Align steel control point base corner exactly with the marker center. View from directly above to verify alignment. The sharp corner of the base should touch the exact center of the marker.

4. Lower scanner onto the steel base smoothly without disturbing the base alignment

5. Open Control Point Mode in LixelGO by tapping the CP icon

6. Tap "+" to add new control point

7. Enter point name EXACTLY as it appears in the CSV coordinate file (case-sensitive, space-sensitive). "CP01" does not match "cp01" or "CP 01". Any mismatch causes processing failure.

8. Tap OK. The scanner flashes green for approximately 1 second to confirm the point was marked.

9. Wait motionless for 5 seconds after the confirmation flash. This dwell period allows the scanner to accumulate point cloud data of the control point area.

10. Lift slowly and walk 1-2 complete circles around the control point at 2-3 meter radius. This circling ensures adequate point cloud coverage of the control point from multiple angles, improving the automatic matching process during post-processing.

11. Continue to next control point or resume normal scanning

The 5-second dwell and 1-2 circle pattern are critical for successful control point processing. Insufficient coverage causes automatic matching failures during post-processing.

GCP Processing in LixelStudio

After transferring scan data and preparing the coordinate CSV file:

1. Check "Control Point" in the Coordinate Transformation section of Project Processing

2. Click import button and select the prepared CSV coordinate file

3. Click "Control Point Editing" to open the control point matching interface

4. Verify automatic matching: The software attempts to automatically match the marked control points in the scan to the coordinates in the CSV file based on point names. Check that all points show green checkmarks indicating successful matching.

5. Designate check points: Use 70-80% of control points for the transformation, reserving 20-30% as check points. Uncheck the boxes next to points you want to reserve as check points. Check points are not used in the transformation calculation but are used to independently verify achieved accuracy.

6. Click "Check" to review the visualization. The software displays control points and their residuals graphically. Look for points with large residuals (>10cm) that might indicate problems.

7. If visualization looks good, click "Confirm" to accept the control point configuration

8. Start processing. The software performs SLAM optimization constrained by the control point positions.

GCP Quality Assessment

After processing completes, review the accuracy report:

Good residuals: 1-3cm at control points used in transformation indicates excellent fit. This level suggests the scan, survey, and transformation all performed well.

Concerning residuals: >5cm residuals warrant investigation:

• Verify surveying was performed correctly
• Check control point marking procedure (5-second dwell, circling)
• Verify point names match exactly
• Review control point distribution (geometric diversity)

Check point assessment: Check points (those not used in transformation) should show residuals similar to the control points. If check point residuals significantly exceed control point residuals (by 2-3× or more), the control point network may be inadequate or poorly distributed.

Common GCP Errors and Solutions

Name mismatch errors are the most common problem:

• "CP01" in CSV but marked as "cp01" in field (case sensitive)
• "CP01" in CSV but marked as "CP 01" in field (space sensitive)
• "CP-01" in CSV but marked as "CP01" in field (character sensitive)

Solution: Be extremely careful with naming. Use simple names without special characters. Verify spelling before confirming in LixelGO.

Insufficient control point coverage:

• Operator moved too quickly, didn't perform 5-second dwell
• Operator didn't circle the control point 1-2 times
• Point cloud has gap where control point should be

Solution: Follow the marking procedure carefully. Review point cloud after scanning to verify control points are captured.

Poor alignment:

• Steel base corner offset 1-2cm from marker center
• Base moved during scanner placement
• Marker center ambiguous or poorly defined

Solution: Take time to align base precisely. View from directly above. Use markers with clearly defined centers.

Wrong base used:

• Tripod used instead of steel control point base
• Scanner placed directly on ground without base
• Non-standard base used

Solution: Always use the provided steel control point base for control point marking.

File format errors:

• XLSX file instead of CSV
• Wrong header text
• Blank lines in file
• Extra commas or missing commas

Solution: Save as CSV from spreadsheet software. Open in text editor to verify format matches required template exactly.

Measurement Point Workflow (L2 Pro Only)

Measurement Point workflow enables marking indoor locations that inherit outdoor RTK accuracy through SLAM-RTK fusion. This feature bridges GPS-denied indoor areas with GPS-enabled outdoor areas.

Concept and Requirements

Firmware requirement: Scanner firmware 2.3 or later required for measurement point functionality.

RTK requirement: Good RTK fixed solution must be established outdoors before entering GPS-denied area.

Distance limitation: Maximum 100 meters from last RTK fixed position. Accuracy degrades with distance from RTK coverage.

L2 Pro exclusive: This feature is not available on K1 hardware due to different RTK module integration.

Accuracy Degradation with Distance

Within 50 meters of last RTK fix: Approximately 5cm horizontal and vertical RMSE achievable through SLAM-RTK fusion.

Within 100 meters of last RTK fix: Approximately 10cm horizontal and vertical RMSE. Still adequate for many applications but approaching the accuracy limit.

Beyond 100 meters: Accuracy degrades to >10cm RMSE and continues degrading with distance. SLAM drift accumulates without RTK constraint.

The accuracy estimate displayed in the output file provides guidance on reliability. Points with accuracy estimates exceeding 15cm should be used cautiously.

Field Procedure

1. Establish RTK fixed solution in outdoor area adjacent to the GPS-denied zone. Verify green RTK indicator light and Fixed status in LixelGO.

2. Walk L-shaped path (approximately 10m × 10m) with RTK before entering building. This provides geometric diversity in the RTK-constrained trajectory, improving fusion quality.

3. Scan around building exterior with RTK to establish context and reference frame.

4. Note the location where RTK is lost when entering the building. This entry point marks the boundary between RTK-constrained and SLAM-only portions of the trajectory.

5. Enter building or GPS-denied area. Continue scanning normally as RTK indicator changes to blue or red.

6. Mark measurement points at desired locations using Tools → Add Measurement Point in LixelGO. Enter descriptive names for each point ("Building Corner NW", "Equipment Center", "Reference Wall East", etc.).

7. Return to outdoor RTK area if possible. Exiting back to RTK coverage creates a loop that improves measurement point accuracy. However, this is not required—one-way scans (outdoor to indoor only) still produce usable measurement points.

Post-Processing and Output

After processing the project in LixelStudio (using RTK for coordinate transformation), measurement point coordinates are automatically exported.

Navigate to the project folder on the computer. Open the subfolder named "measurepoint". Locate the file "measure_points_latest.csv".

The CSV file contains columns:

• Point Name: The name entered in LixelGO
• Easting: X coordinate in the output coordinate system
• Northing: Y coordinate
• Height: Z coordinate or elevation
• Timestamp: When the point was marked during scanning
• Accuracy Estimate: Software's estimate of achieved accuracy in meters

Points with accuracy estimates exceeding 15cm should be flagged for cautious use. Consider rescanning or using traditional survey methods to verify these points if they are critical.

Measurement points can be used as approximate control points for subsequent scan sessions in the same area, extending RTK accuracy deeper into GPS-denied zones through multiple connected sessions.

Hybrid Workflows

Combining multiple georeferencing methods in the same project provides robustness, accuracy verification, and complete coverage of mixed environments.

RTK Primary with GCP Verification

This workflow uses RTK for primary georeferencing while employing ground control points for independent verification.

Planning phase: Survey 3-5 control points distributed across the site at 100-200 meter spacing. Control points should be located in areas with good satellite visibility where RTK is reliable.

Field phase: Scan with RTK enabled throughout. When passing near control points, perform the control point marking procedure (align base, mark in app, dwell 5 seconds, circle point).

Processing phase: Enable both RTK and GCP in Coordinate Transformation settings. Designate 1-2 control points for use in the transformation alongside RTK. Reserve the remaining control points as check points (disable their checkboxes in control point editing).

Benefits: Independent verification catches systematic RTK errors (wrong Source Ellipsoid setting, datum transformation errors, base station problems). The check points provide quantitative accuracy assessment. If RTK fails in portions of the scan, the control points can constrain those sections.

Use case: Critical projects requiring documented accuracy, large projects where RTK reliability might vary, projects bridging multiple RTK coverage zones.

GCP Indoors with RTK Outdoors

This workflow provides complete coverage of mixed indoor-outdoor sites by using appropriate georeferencing methods for each environment.

Planning phase: Identify transition zones where scanning will enter and exit buildings. Place control points at these transitions (doorway exteriors, building entrances). Survey additional control points inside the building in locations that will be scanned.

Field phase:

1. Begin scanning in outdoor area with RTK active (green indicator light)
2. When approaching building entrance, mark the transition control point before entering
3. Continue scanning indoors (RTK will be lost, red indicator light)
4. Mark interior control points as you encounter them during indoor scanning
5. When exiting building, mark the exit transition control point (RTK should return to green after exiting)

Processing phase: Enable both RTK and GCP in coordinate transformation. RTK constrains the outdoor portions. Control points constrain the indoor portions and tie indoor to outdoor through transition points.

Benefits: Complete georeferencing coverage of sites that combine GPS-enabled and GPS-denied areas. Achieves uniform accuracy throughout rather than having degraded accuracy in GPS-denied sections.

Use case: Campus scanning (buildings and grounds), industrial facilities (indoor and outdoor areas), infrastructure projects (tunnels with outdoor approaches).

RTK with Periodic Control Points for Large Projects

This workflow provides continuous accuracy monitoring and backup georeferencing across extended multi-day projects.

Planning phase: Establish permanent or semi-permanent control points at major locations across the project site at 200-300 meter spacing. These control points serve as long-term references that can be reoccupied across multiple site visits.

Field phase: Each scanning session uses RTK as the primary georeferencing method. When passing near established control points, opportunistically mark them even though RTK is active. Over time, each control point will be marked in multiple scan sessions on different days.

Processing phase: Process each day's scans with RTK as primary method. Use control points as check points to monitor RTK accuracy. If any session shows RTK problems (loss of fix, wrong coordinates), that session can be reprocessed using control points for georeferencing.

Benefits: Robustness against RTK failures (provides backup georeferencing method), continuous accuracy monitoring (check points reveal RTK problems immediately), consistency verification across multiple site visits (control points tie together sessions captured weeks or months apart).

Use case: Construction progress monitoring over months or years, large infrastructure projects with multiple mobilizations, monitoring projects requiring consistent reference frame across time.

Camera Coloring Workflow Decisions

Camera coloring adds RGB color information to point clouds by projecting panoramic imagery onto geometry. Understanding when to enable or disable this feature optimizes workflow efficiency and results quality.

When Camera Coloring Provides Value

Client presentations and visualizations: Colored point clouds are dramatically more intuitive for stakeholders unfamiliar with point cloud data. Color enables immediate recognition of materials, spaces, and features.

Material identification: Color helps distinguish materials that have similar geometry but different appearance (painted steel vs. bare steel, different paint colors, signage, equipment labels).

Spatial orientation: Color helps operators and reviewers quickly orient themselves in complex spaces by recognizing familiar visual landmarks.

Documentation of current conditions: Captures paint colors, signage, equipment markings, and other visual details useful for as-built records.

When Camera Coloring Introduces Problems

Measurement-only deliverables: If point cloud will only be used for dimension extraction and the client doesn't need visualization, color adds processing time without benefit.

Extreme lighting conditions: Bright sun with deep shadows, very dark interiors, or harsh backlighting creates poor color quality with overexposed and underexposed areas that may reduce deliverable quality.

Quick processing requirements: Camera coloring increases processing time by 30-100% depending on settings. When tight deadlines require fastest processing, disable coloring.

Limited storage: Colored point clouds are typically 30-40% larger than intensity-only point clouds. Projects with severe storage constraints may need to disable coloring to reduce file sizes.

Decision Framework

Ask these four questions to decide on camera coloring:

1. Does the deliverable specification require or benefit from color? If yes → enable. If no → consider other factors.

2. Can lighting conditions produce acceptable color quality? If yes → enable. If no → disable or plan separate color capture under better conditions.

3. Is processing time available? If yes → enable. If no → disable or process subset with color.

4. Is storage adequate? If yes → enable. If no → disable or reduce output resolution.

Camera Configuration in LixelGO

Camera settings must be configured BEFORE scanning begins. Camera data cannot be added retroactively to scans captured without camera enabled.

Navigate to Settings → Camera in LixelGO. Enable or disable "Built-in Camera" toggle. When enabled, the scanner captures panoramic imagery synchronized with LiDAR data throughout the scan session.

Best practice: Capture a brief 15-30 second test scan with camera enabled. Review the preview in LixelGO to verify cameras are functioning and image quality is acceptable before starting the main scan. This test prevents discovering camera problems after completing a long scan session.

Post-Scan Coloring Decisions in LixelStudio

After scanning with camera enabled, the coloring workflow can be refined during processing.

In LixelStudio Project Processing, the Camera Coloring section provides options:

• Built-in Camera Coloring: Enable to project scanner camera imagery onto geometry
• Optimize Visual Pose: Use visual features to refine trajectory (improves accuracy in textured environments, can cause problems in texture-poor environments)
• Output Panorama: Export panoramic images alongside point cloud
• Resolution: Higher resolution produces better color quality but increases processing time

For scans captured with external panoramic cameras (Insta360, Ricoh Theta, etc.), LixelStudio supports importing and projecting external imagery during processing. This workflow enables capturing geometry and color separately under optimal conditions for each.

Basic Single-Scan Processing Workflow

Processing transforms raw scanner data into usable point clouds through SLAM optimization and optional georeferencing.

LixelStudio Project Processing Interface

Launch LixelStudio and navigate to Project Processing. Click "Import Project" and select the project folder copied from the scanner. The folder contains timestamped subdirectories with raw sensor data.

After import, the processing configuration interface displays sections for Coordinate Transformation, Camera Coloring, Advanced Settings, and output options.

Processing Configuration Options

Coordinate Transformation section: Select georeferencing method based on data collection:

• None: Produces point cloud in arbitrary local coordinates (origin at scanner initialization position)
• GNSS (RTK): Uses RTK data recorded during scanning
• GNSS (PPK): Imports base station files and processes kinematically
• Control Point: Uses surveyed control points marked during scanning
• Combinations: Multiple methods can be enabled simultaneously (RTK + GCP, PPK + GCP, etc.)

Camera Coloring section: Enable if camera was used during scanning and color is desired in deliverables. Disable to process geometry-only point cloud (faster, smaller files).

Advanced Settings section: Leave at defaults for initial processing attempt. Advanced options enable troubleshooting processing failures, optimizing for specific environments, and tuning quality/performance tradeoffs.

Initiating and Monitoring Processing

After configuring options, click "Start" to begin processing. The software does not allow pausing and resuming—once started, processing continues until completion or failure.

Monitor the progress window showing current processing stage and estimated remaining time. Note that the time estimate is approximate and varies based on hardware performance and data complexity.

Processing stages:

1. Data loading: Reads raw sensor data from project folder
2. Preprocessing: Formats data for optimization algorithms
3. SLAM optimization: Computes scanner trajectory and map (typically 60-70% of total time)
4. Coloring (if enabled): Projects camera imagery onto geometry
5. Coordinate transformation (if enabled): Applies georeferencing
6. Export: Writes final point cloud to output file

Processing Completion and Output Files

Upon successful completion, processing generates outputs in a "result" subfolder within the project directory:

• Point cloud file (.las or .laz format): Main deliverable containing xyz coordinates, intensity, and RGB color (if enabled)
• Trajectory file: Scanner positions and orientations throughout scan
• Accuracy report (if coordinate transformation was enabled): Residuals and statistics
• Processing log: Details of processing parameters and any warnings

The processing time for typical projects is approximately 20-30× the scan duration on recommended hardware. A 10-minute scan processes in 120-180 minutes (2-3 hours). Longer scans, camera coloring, point cloud enhancement, and less powerful hardware increase processing time proportionally.

Processing Failures and Recovery

Processing failures occur when SLAM optimization cannot find a stable solution, memory limits are exceeded, or configuration errors prevent successful coordinate transformation. Understanding failure modes and recovery strategies enables salvaging problematic scans.

LIO Trajectory Drift Error

"LIO trajectory drift detected" error indicates accumulated position errors exceed acceptable limits. This error appears during the SLAM Optimization stage and typically results from feature-poor environments, excessively long scans without adequate loop closures, or extreme scanner motion.

Recovery strategies (try in order):

Strategy 1 - Robust Mode: Navigate to Advanced Settings → Special SLAM Mode → Select "Robust Mode". This mode uses more conservative optimization that tolerates higher drift at the cost of slightly reduced accuracy. Succeeds in 60-70% of cases where default mode failed.

Strategy 2 - Partial Processing: Navigate to Advanced Settings → SLAM Mapping End Time Selection. Process only the first portion of the scan (for example, first 15 minutes of a 25-minute scan). This truncates the scan before drift becomes excessive. Useful when early portions are good but later portions developed tracking problems.

Strategy 3 - Loop Closure: Navigate to Advanced Settings → Debug Options → Enable "Start-to-End Loop Closure". ONLY use if the scan actually formed a complete loop by returning to the starting position. Forces the SLAM algorithm to close the loop which can correct accumulated drift. Using this option on scans that did NOT form complete loops degrades accuracy.

Strategy 4 - Narrow Scene Mode: Navigate to Advanced Settings → Special SLAM Mode → Select "Narrow Scene". ONLY use for feature-poor environments like tunnels, mines, or long corridors under 500 meters length. This mode adjusts SLAM to handle limited lateral features. Using this mode in normal environments causes processing failure.

Strategy 5 - Professional Support: Contact XGRIDS technical support with the project folder. Support engineers can analyze the data and potentially split the scan into segments for independent processing and later fusion.

If all strategies fail, the scan has fundamental problems requiring re-scanning with better technique (slower movement, more loops, added temporary features).

Memory Exhausted Errors

Memory exhausted errors occur when SLAM optimization requires more RAM than available on the computer.

Approximate RAM requirements by scan duration:

• 10-minute scans: 20-30GB
• 20-minute scans: 40-60GB
• 30-minute scans: 80+ GB (especially with point cloud enhancement)

Recovery strategies:

Strategy 1 - Close Applications: Close all unnecessary applications to free maximum RAM. Verify available RAM in Task Manager (Windows) or Activity Monitor (Mac) exceeds 40GB before processing.

Strategy 2 - Low-Memory Mode: Navigate to Advanced Settings → Enable "Low-Memory Reconstruction". This trades processing speed for reduced memory usage by offloading intermediate data to disk. Processing becomes 30-50% slower but succeeds with less RAM. Only available for single-scene processing (not map fusion).

Strategy 3 - Reduce Duration: Use SLAM Mapping End Time Selection to process shorter portion of scan. 20-minute scan failing on 64GB RAM might succeed if processed as first 15 minutes only.

Strategy 4 - Disable Enhancement: If Point Cloud Enhancement is enabled, disable it. Enhancement dramatically increases RAM requirements. Process without enhancement first, verify quality is acceptable, then consider upgrading RAM for enhanced reprocessing if needed.

Strategy 5 - Hardware Upgrade: Upgrade computer RAM from 64GB to 128GB. This provides headroom for complex scans and enables processing longer sessions with point cloud enhancement.

Coordinate Transformation Errors

Coordinate transformation errors prevent georeferencing even when SLAM processing succeeds.

Control point matching errors: Most common issue is point name mismatch. Verify names in CSV file exactly match names entered in LixelGO during scanning (case-sensitive, space-sensitive). Verify CSV format matches requirements exactly. Verify column order is Point Name, Easting, Northing, Height.

RTK transformation errors: Verify Source Ellipsoid setting matches RTK provider output (usually WGS84). Verify Target Coordinate System is configured correctly for desired output.

Datum transformation errors: When transforming between different datums (WGS84 to NAD83), verify transformation parameters are correct with proper signs and not transposed.

Disk space errors: Coordinate transformation can temporarily require substantial disk space (2-3× raw scan size). Free disk space on the system drive. Change output path to a drive with more available space. Add external storage if internal drives are full.