7.4 Map Fusion Collection Strategy
Map Fusion joins multiple PortalCam scan segments into a single scene in LCC Studio. How you collect each segment determines whether fusion succeeds. The decisions happen in the field, not in the software.
Map Fusion Hard Limits
LCC Studio Map Fusion has firm constraints that cannot be worked around in processing. Plan your field collection to stay within these limits before you scan, not after.
Complete overlap between segments also causes failure. If one segment's scan path is entirely contained within another segment's scan path, LCC Studio cannot determine the correct spatial relationship between them. Each segment must cover some unique area, with a 15-meter overlap zone as the connection bridge, not as the entire content of the segment.
Selecting Fusion Points
A fusion point is the physical location where two scan segments connect. LCC Studio aligns segments by matching geometry in their overlap zones. If the geometry in the overlap zone is insufficient, the alignment fails regardless of how good the rest of the scan is. Choosing fusion points carefully is one of the highest-leverage decisions in a multi-segment project.
Characteristics of a Good Fusion Point Location
- Open area with geometry visible in multiple directions: A lobby, corridor intersection, or equipment cluster gives the alignment algorithm geometry to work with from multiple approach angles. A blank wall section does not.
- Rich surface features: Corners, objects, columns, door frames, and surface texture variation all contribute to alignment confidence. Featureless surfaces like painted ceilings or plain floor tiles contribute very little.
- Stable and unchanging: Avoid areas where objects move between segments: stacked materials, parked vehicles, staging areas, or any location where people tend to gather. Moving geometry between segments defeats the alignment process.
- Physically accessible: The fusion point needs to be scanned thoroughly by both segments. Choose locations you can return to and walk through from the same approach direction on the second visit.
The PortalCam Fusion Collection Method
The standard collection sequence for a PortalCam Map Fusion project follows a consistent pattern for each segment: initialize at or near a fusion point, scan a complete loop of the coverage area, and end the segment at the next fusion point. This produces the overlap zones that LCC Studio uses for alignment without requiring the scanner to travel back to the start.
Plan fusion points before scanning
Identify the locations where segments will connect before you arrive at the site. Mark them on a floor plan sketch. Assign a name to each point using your control point naming convention. For a three-segment project, you need a minimum of two fusion point locations, one shared between segment 1 and 2, and one shared between segment 2 and 3.
Initialize segment 1 at or near the first fusion point
Place the PortalCam on the tripod at a stable, feature-rich location within the first fusion zone. Complete the standard 15-second static initialization and 15-second static dwell before picking up the device.
Scan the coverage area in a complete loop
Move through the intended coverage area for segment 1 using proper PortalCam technique: multi-height passes, bidirectional coverage on major corridors, and closed loops where the scan path returns to previously scanned geometry. This produces the internal consistency the SLAM algorithm needs.
End segment 1 within the overlap zone of the next fusion point
When coverage for segment 1 is complete, scan into the overlap zone of the next fusion point location for at least 50 ft (15 m) before stopping. Mark any control points required for fusion before ending the segment.
Initialize segment 2 within the overlap zone
Begin segment 2 at least 50 ft (15 m) before the end point of segment 1. Initialize in a location that segment 1 also covered. The first 50 ft (15 m) of segment 2 should cover the same geometry that the last 50 ft (15 m) of segment 1 covered.
Continue through the overlap zone and into new coverage area
Scan through the entire overlap zone before advancing into territory that segment 1 did not cover. This ensures both segments have data from the connection area that LCC Studio can use for alignment.
Connection Methods: RTK, Control Points, and Hybrid
LCC Studio requires each segment in a Map Fusion project to connect to at least one other segment through either RTK data or shared control points. Segments that have neither cannot be fused with anything.
RTK-Based Fusion
When each segment has valid RTK data, LCC Studio uses the absolute coordinates from each segment's RTK track to align them in a shared coordinate system. This is the most reliable method when outdoor or open-sky RTK signal is available. RTK fix must be active during the overlap zone of each segment for the connection to be valid.
For RTK fusion to work, the RTK status must be Fixed (not Float or Single Point) during the portion of each segment that contains the overlap zone. A segment where RTK was only Fixed in areas that do not overlap with another segment provides no fusion connection, even if the segment itself processed correctly.
Control Point Fusion
When RTK is not available, use shared control points to connect segments. The control points do not provide absolute coordinates unless they are also surveyed. What they provide is a spatial anchor that both segments reference, allowing LCC Studio to determine their relative positions.
For control point fusion, segments 1 and 2 must each contain at least one control point with the same name. If segment 2 and segment 3 also need to connect, they need their own shared control points. A control point in segment 1 that segment 3 does not share does not connect segments 1 and 3 directly.
Hybrid Fusion
A combination of RTK and control points provides the strongest fusion result. Segments with RTK contribute absolute coordinate alignment. Control points constrain relative drift within and between segments. Use the hybrid approach on any project where absolute accuracy matters and indoor conditions limit RTK reliability: mark control points in indoor segments and rely on RTK for outdoor segments, with shared points bridging the transition zones.
Valid Fusion Connection Examples
Segment Naming for Map Fusion Projects
Use a consistent naming convention that communicates building, floor, and segment number. A pattern like BuildingName_Floor_SegmentLetter produces names that sort correctly and are unambiguous when loaded into LCC Studio.
Examples: MainLibrary_FL1_SegA, MainLibrary_FL1_SegB, MainLibrary_FL2_SegA. Keep names under 30 characters to avoid file system path length issues on some Windows configurations. Do not use spaces or special characters.
Control point names in the fusion project must match exactly between segments, including capitalization. A point named FP_01 in segment A and fp_01 in segment B will not be recognized as the same point by LCC Studio and the connection will fail silently during processing.
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