Plan the Route and Quality Checks Before Scanning

For a reliable handheld simultaneous localization and mapping (SLAM) scan, walk smoothly at a steady pace, plan overlapping closed-loop routes, slow down at doorways and stairs, add temporary features where the scene is repetitive, and monitor coverage while still on site. These practices reduce capture risk but do not establish accuracy by themselves; review the trajectory, photos, point cloud, coordinate setup, and separate independent check points against the project requirements. Scan quality depends jointly on the device model, site conditions, route, and office quality control.

This guide explains how to control those factors for renovation measurement, building inspection, as-built surveying, underground or tunnel work, historic buildings, and steel structures.

Figure 1: Control route and coverage in the field, then review the trajectory, coordinates, check points, and deliverables in the office.

Walking Speed

Walk at a steady pace: Move smoothly at the speed recommended for the device; avoid sudden stops and sharp turns;

• Consequences of moving too fast: Motion blur, trajectory jumps, and point-cloud distortion may occur, and the affected section will usually need to be rescanned;
• Consequences of moving too slowly: Remaining stationary for too long can reduce the accumulation of useful SLAM features;
• Rule of thumb: A natural walking pace is sufficient. There is no need to slow down deliberately, but do not walk quickly.

Closed-Loop Routes

A closed loop means returning near the route’s starting point to close it. It is one important measure for constraining accumulated SLAM drift; effectiveness still depends on scene features, route design, and successful loop recognition:

• Complete at least one closed loop in every room;
• Create loops at both ends and around turns in key areas such as long corridors and halls;
• For multi-room projects, complete a loop within each room and transition quickly between rooms;
• After returning to the start, overlap part of the initial route so that the algorithm can recognize the closure.

Turning and Device Orientation

Turning: Slow down as you approach a corner, then resume your normal pace after the turn. Avoid turning rapidly in place;

• Orientation: Keep the front of the device facing forward and hold it level and steady. Avoid large upward or downward angles;
• Confined spaces: Move along the wall with the device angled sideways at approximately 45° to reduce feature loss;
• Doorways and stairs: Slow down while passing through them. Doorways and stairs are among the places where SLAM is most likely to lose features.

Strategies for Spaces with Limited Features

The following spaces provide few distinguishing features, making SLAM more prone to drift. Add features proactively:

Real-Time Quality Control

Use the SHARE Capture app’s live preview to assess quality during scanning rather than waiting until you return to the computer:

1. Check live point-cloud coverage: If the preview shows obvious gaps, rescan them on site;
2. Check the field trajectory preview: During scanning and before confirming that the task has been saved, check whether the trajectory covers the planned route, forms a closed loop, and contains abnormal jumps;
3. Watch for warnings: The device issues prompts when the tilt is excessive or the movement speed is too high. Adjust your technique or end and save the scan as instructed;
4. Rescan promptly: If a section shows obvious drift or insufficient coverage, do not wait. Rescanning that section is usually more efficient than repeating the entire site later.

The SHARE PointClouds Studio V2.6 Quality-Control Loop Back at the Computer

1. Check data integrity: Copy the complete raw directory without changing filenames or folder hierarchy;
2. Review after processing: After reconstruction, SHARE PointClouds Studio V2.6 can link the processed trajectory, photos, photo points, and plan/3D viewports to locate anomalies and review doorways, stairs, occluded components, and color coverage. This is an office review step and does not replace the field checks performed in the SHARE Capture app;
3. Process multiple capture tasks: If the site was captured as separate scan tasks, process the tasks separately, then use manual corresponding-point registration in reliable overlap areas before merging. A single complete scan cannot be split into separate reconstruction tasks during post-processing; post-processing can only crop or delete unwanted point-cloud data;
4. Coordinates and global navigation satellite system (GNSS): Use real-time kinematic (RTK) positioning or control points when engineering coordinates are required. When real-time GNSS conditions are insufficient, generate an RTKLIB POS trajectory file in an external post-processed kinematic (PPK) tool, then select it in SHARE PointClouds Studio only as the GNSS Fusion Trajectory Source. Alternatively, apply coordinate transformation to an existing point cloud;
5. Independent checks: SHARE PointClouds Studio V2.6 supports 3D/elevation accuracy check workflows and report export. Control points establish or transform the coordinate frame; separate independent check points verify the result and must not be reused as control points;
6. Drafting and presentation: Batch section extraction and orthogonal snapping can support computer-aided design (CAD)-assisted drafting. CAD drawing export simultaneously generates drawing exchange format (DXF) and DWG files and includes them in the exported ZIP package. The drawings require manual review; RVT, IFC, complete building information modeling (BIM) models, and SketchUp deliverables remain downstream professional workflows. 3D Gaussian splatting (3DGS) is intended only for photorealistic viewing; use the point cloud as the basis for dimensions and drafting. When scanning complex indoor spaces, begin with a pilot area, capture each area as a closed loop, and carefully inspect level separation, colorization, and areas near floor slabs before expanding the scope of work.

Saving and Ending a Scan

• End the scan after completing the closed loop;
• Wait until the app confirms that saving was successful before powering off or removing the card. Powering off or removing the card too early is one of the most common causes of data corruption;
• Check point-cloud file size and integrity on site before leaving.

Frequently Asked Questions

Q1: Can I pause while scanning? You can pause briefly, but avoid remaining stationary for a long time. When you begin moving again, try to return to the closed-loop route.

Q2: What happens if I walk too fast? Motion blur and trajectory jumps can occur, and the affected section will usually need to be rescanned. Maintaining a steady pace is a basic requirement.

Q3: How can I tell whether a scan is usable? In the field, use the SHARE Capture app to review live point-cloud coverage and the trajectory preview. Confirm that the route covers the planned area, forms a closed loop, and contains no obvious jumps, then wait for the app to confirm that saving succeeded before leaving. After reconstruction, SHARE PointClouds Studio V2.6.0 can be used for office review of the processed trajectory, photos, and point cloud.

Q4: How should I plan a route for a building with many rooms? Complete a separate loop in each room and transition quickly between rooms. Scan priority rooms first, then cover secondary areas. If floor-by-floor deliverables are required, plan separate scan tasks in the field, capture and save each floor as its own task, reconstruct each task separately, and only then manually select at least three pairs of clear, fixed corresponding feature points. Confirm the overlap/error preview before merging.

Q5: If the RTK status indicator looks normal, does that mean the result meets the project’s accuracy requirement? No. The indicator only assists in evaluating GNSS data status. You must still verify the coordinate system and trajectory and assess the result with separate independent check points. Where needed, use control points or generate an RTKLIB POS file in an external PPK tool and select it in SHARE PointClouds Studio only as the GNSS Fusion Trajectory Source.