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From Measuring Individual Dimensions to Recording the Complete Space
A handheld simultaneous localization and mapping (SLAM) scanner captures continuously through rooms, corridors, stairs, and floors, preserving walls, openings, floor heights, spans, and spatial relationships as a measurable point cloud. For renovation remeasurement, existing-building documentation, and as-built dimensional verification, a team can capture planned dimensions on site and later return to the three-dimensional record to extract additional measurements, sections, and relationships wherever point-cloud coverage and quality are sufficient.
In a published test, SHARE SLAM S20 achieved a mean absolute error (MAE) of 3.42 mm and a root mean square error (RMSE) of 4.17 mm across 40 dimensional comparisons in a three-story unfinished building. The results demonstrate its measurement performance for renovation remeasurement, existing-building documentation, and as-built dimensional verification; project deliverables can be confirmed with independent check reports.
Project Value of Complete Spatial Capture
| Work item | Tape measure or laser distance meter | SHARE SLAM complete spatial capture |
|---|---|---|
| Site record | Measure and record dimensions one by one according to a checklist | Capture visible spaces and their relationships continuously along a planned route |
| Renovation remeasurement | Efficient for quick checks of a door, cabinet position, or selected dimension | Supports whole-property, multi-room, stair, and floor-height remeasurement, with later extraction from the point cloud |
| Existing-building documentation | Produces records of selected dimensions | Preserves the visible three-dimensional condition at capture time for design communication and change comparison |
| As-built dimensional verification | Checks items individually against drawings or an acceptance list | Locates inspection areas in a complete point cloud and combines critical dimensions with independent check reports |
| Spatial relationships | Relies on sketches, photos, and dimension schedules to connect observations | Shows rooms, openings, floors, and components in one spatial reference |
| Downstream outputs | Dimension schedules, sketches, or field notes | Point clouds, sections, and computer-aided design (CAD) support; CAD export creates both DXF and DWG files in the exported ZIP package |
Tape measures and laser distance meters remain useful for rapidly confirming an individual dimension and can serve as independent reference tools. The advantage of handheld SLAM is that it extends isolated dimensions into a complete, reviewable, and traceable spatial record shared by remeasurement, inspection, drafting, and modeling teams.
Published Study: 40 Measurement Pairs in a Three-Story Unfinished Building
The SHARE3DCAM team conducted a published study in a three-story unfinished building in Dongguan. A SHARE SLAM S20 captured the space continuously, while a laser distance meter provided reference measurements between quadrant targets mounted on the walls. The study contains 40 measurement pairs and is identified by the digital object identifier (DOI) 10.5281/zenodo.21821068.
Figure 1: The study setup included a SHARE SLAM S20, a laser distance meter, and quadrant targets mounted on the walls.
| Metric | Result |
|---|---|
| Sample | 40 measurement pairs in a three-story unfinished building |
| MAE | 3.42 mm |
| RMSE | 4.17 mm |
| Maximum deviation | 10 mm |
| Recorded time | 11 minutes scanning + 25 minutes processing = 36 minutes; 60 minutes recorded for sequential laser-distance measurements |
MAE describes the average absolute deviation across the 40 measurement pairs, while RMSE gives greater weight to larger deviations. Together, they help a project team understand the error distribution in this sample. For renovation remeasurement, the study demonstrates the feasibility of capturing a multi-floor unfinished building continuously and then extracting many dimensions within one spatial record. For existing-building documentation, the point cloud preserves each measurement location with its surrounding geometry. For as-built dimensional verification, inspectors can locate an item in the point cloud and add project-specific independent check-point results to a traceable report.
When citing the study, retain the test object, 40-pair sample, reference method, MAE, RMSE, and DOI so that readers can return to the published method and records.
How to Produce an Independent Check Report
- Define inspection items: Identify critical rooms, components, elevations, and tolerances for renovation remeasurement, existing-building documentation, or as-built dimensional verification.
- Arrange independent check points: Keep check points separate from points used for control calibration or coordinate transformation, and distribute them across priority project areas.
- Complete point-cloud processing: Inspect route, loop closure, coverage, occlusion, noise, units, and coordinate systems, then retain the project and processing records.
- Run 3D and elevation checks: In SHARE PointClouds Studio V2.6, perform the 3D accuracy check and elevation accuracy check separately and export the corresponding reports.
- Review critical dimensions: Compare report statistics, maximum deviation, sample scope, and selected critical dimensions with project requirements; retain field records or supplementary capture for any exception.
The complete spatial record and independent check reports then allow designers, contractors, survey teams, and owners to review the same location, dimension, and validation basis.
Combining Tape and Laser Measurements with a Point-Cloud Workflow
- Door widths, equipment interfaces, or one selected dimension: Use a tape measure or laser distance meter for a rapid check.
- Whole properties, multiple floors, or many dimensions: Use SHARE SLAM for continuous capture and reduce the work required to connect isolated field records.
- Priority acceptance dimensions: Extract measurements from the point cloud, then sample-check them with an independent reference method required by the project.
- Long tape measurements: Record tension, level alignment, support, sag, and endpoint alignment so the reference observation can be reviewed.
- Downstream drafting and modeling: Use the point cloud and check reports to extract sections and support CAD drafting in SHARE PointClouds Studio V2.6. CAD drafting export generates both DXF and DWG files in the exported ZIP package. RVT, IFC, and complete building information modeling (BIM) deliverables are created through downstream professional workflows.
Frequently Asked Questions
What does the 40-pair test in a three-story unfinished building mean for renovation remeasurement? It presents a published method and result for continuous capture followed by multiple dimensional measurements across floors and rooms. A project team can use the method to plan its own representative area and independent check points, then confirm critical dimensions in a project report.
How should MAE 3.42 mm and RMSE 4.17 mm be interpreted? MAE is the average absolute deviation across the 40 measurement pairs. RMSE gives more weight to larger deviations. Read both with the sample size, maximum deviation, reference method, and DOI.
How does a complete point cloud support an existing-building record? It preserves the three-dimensional positions and relationships of surfaces visible at capture time. Teams can later measure, extract sections, communicate designs, and compare changes. Occluded areas can be supplemented on site or documented with photos and project records.
How can a team confirm that a point cloud supports as-built dimensional verification? Define tolerances and the sample scope, use independent check points to run separate 3D and elevation checks, export the reports, and include statistics and selected critical-dimension records in the acceptance package.
Can point clouds enter CAD or BIM workflows? Yes. SHARE PointClouds Studio V2.6 supports section extraction, orthogonal snapping, and CAD-assisted drafting. CAD export generates both DXF and DWG files in the exported ZIP package. RVT, IFC, and complete BIM models are modeled and verified by downstream professionals.
