8.3 Multi-Scan Map Fusion in LixelStudio

When to Use Map Fusion in LixelStudio

Map Fusion in LixelStudio stitches multiple scan segments into a single registered point cloud. Use it when a project required more than one scan session due to battery changes, RAM limits, site access constraints, or area size. All segments must have been collected with fusion in mind, as overlapping geometry and shared connection points or RTK coverage cannot be added after the fact.

Connection Methods

Adjacent segments must be linkable through at least one of the following methods. A segment with no connection to any neighbor cannot be included in the fusion job.

RTK-Based Alignment

When all segments have valid RTK data (Fixed status, over 10 satellites, over 33 ft (10 m) of movement while Fixed, antenna tilt within 20 degrees), LixelStudio uses the shared absolute coordinate frame to align them. This is the simplest connection method for outdoor or partially outdoor projects where RTK quality can be maintained across all sessions.

Control Point Alignment

Adjacent segments share control points, physical XGRIDS markers that were scanned in both sessions and given the same name in LixelGO. The name must match exactly, including capitalization. A point named GCP_A in segment 1 and gcp_a in segment 2 is treated as two different points and the connection fails silently. The segment is then isolated and cannot be fused.

Hybrid Alignment

Segments can use RTK for some connections and control points for others, as long as every segment is transitively linkable to every other segment. For example: segment 1 and 2 share RTK, segment 2 and 3 share control points with the same name, and segment 3 and 4 share RTK. All four segments can be fused in a single job.

Fusion Procedure

1. Process each segment individually first. Every segment must complete a successful single-scan SLAM optimization before it can be added to a fusion job. Do not attempt Map Fusion with unprocessed segments.
2. Create a new Map Fusion project in LixelStudio. Upload all processed segments. LixelStudio displays the segments and their connection status based on shared RTK data or matching control point names.
3. Select the reference segment. The reference segment defines the coordinate system for the fused output. Choose the segment with the most stable RTK data or the one whose GCP coordinates define the target system.
4. Review the connection diagram. Every segment must show at least one connection to an adjacent segment. Any isolated segment must be removed or the field data corrected before the fusion job can run successfully.
5. Start fusion processing. LixelStudio runs individual SLAM optimization for each segment, then aligns them, then runs global optimization across the full combined dataset. Do not interrupt between phases.
6. Review segment boundaries in the viewer. After fusion completes, zoom into each boundary zone and check for discontinuities, duplicate geometry, or misalignment. A misaligned boundary indicates a connection point tolerance was exceeded in the field.