4.3 PPK Positioning

How PPK Works

PPK (Post-Processed Kinematic) is supported on both the L2 Pro and the K2. The base station logs raw GNSS data in RINEX format (the standard raw GNSS format) while you scan. Afterward, LixelStudio combines that file with the scanner's own raw log to compute a precise position for every point in the trajectory.

The L2 Pro captures its raw observations through the external RTK module. The K2 captures them through its built-in UM980 receiver. The procedures and minimums on this page apply to both.

RTK vs. PPK: When to Use Which

Both methods use GNSS for absolute coordinate alignment. The difference is when the corrections are applied. RTK applies them live during the scan, pulling corrections from a CORS network (a network of fixed GNSS reference stations) via NTRIP. PPK applies them afterward, processing the raw observations from the scanner and a base station together in software.

Base Station Setup

PPK needs a GNSS base station running at a known position while you scan. It records raw observations (RINEX) that are later combined with the scanner's raw log to compute precise positions across the trajectory. The baseline is the distance between the base and the scanner.

• Set the base at a point with known survey coordinates, or one you will survey after the session
• Keep the baseline under 3 mi. Minimize it wherever possible; accuracy degrades as the baseline grows
• Give the base a clear, unobstructed view of the sky. Base multipath directly degrades PPK quality
• Keep the base antenna stationary the entire session. Any movement during logging invalidates that period
• Log RINEX at 1-second intervals or finer. Confirm the file is complete before leaving; a truncated file cannot be used
• Record the start and end time of the scan. The RINEX file must cover that window with no gaps

Field Collection in PPK Mode

A PPK scan looks much like an RTK scan. The difference is that no NTRIP connection is needed, and the raw observations are stored on the scanner for processing later rather than corrected live.

• Keep the antenna tilt within 20 degrees of vertical throughout the scan
• Include an open section where the sky is unobstructed, so the scanner observes enough satellites for a reliable trajectory
• Cover at least 10 m (33 ft) of open ground for minimum PPK viability
• Avoid scanning during high ionospheric activity. Solar events degrade GNSS and can make PPK unreliable even with good base data
• Do not power off the receiver during the scan. Raw logging is continuous; an interruption creates gaps that cannot be filled afterward

Minimum Requirements

Below these thresholds, PPK completes with compromised accuracy or fails to produce absolute coordinates.

• Baseline: under 3 mi. Shorter is better; keep it under 1 mi for best accuracy
• Open ground in scan: more than 10 m (33 ft) with clear sky
• Valid PPK data points after processing: more than 100, shown in LixelStudio after upload
• Base RINEX: continuous, gap-free, 1-second or finer across the entire scan window
• Antenna tilt: within 20 degrees of vertical throughout

PPK Processing Workflow

PPK processing happens in LixelStudio. The scanner's raw observations and the base RINEX file are processed together to compute a precise trajectory, which is then applied to the point cloud to produce the georeferenced output.

1. Transfer the Base RINEX FileCopy the complete RINEX file to the machine running LixelStudio. Confirm it covers the full scan window with no time gaps.
2. Upload Scan DataTransfer the scan from the device and create a new project as normal.
3. Import RINEX and Confirm Valid Point CountIn the PPK panel, import the base RINEX. LixelStudio computes the PPK solution and shows the valid point count. Confirm it exceeds 100 before proceeding.
4. Set the Target Coordinate System and ProcessSet the source and target systems, ellipsoids, and projection for the deliverable, then process. The PPK trajectory is applied to produce the georeferenced point cloud.