Survey at a glance

Survey control & QA residuals after adjustment

ΔZ = DTM − control elevation. Checks within ±0.5 ft pass. Flagged points have no clear ground return in the reduced cloud (vehicle, occlusion or edge of scan range). Click a row to zoom to the point.

Base map

Survey products from the TLS point cloud

Analysis tools

Hover anywhere for ground elevation (ft).

Drainage potential ponding

Closed depressions in the bare-earth surface deeper than 1 inch: where stormwater would collect before reaching an inlet. Click an area on the map for its depth and volume.

Ground slope share of surveyed ground

8.33 % is the ADA maximum running slope for ramps.

Point classification

Scan metadata

MethodTerrestrial laser scanning (RIEGL)Scan blocks5 (A-1, A-2, B, C, D) Raw points972 MProcessed set18.8 M (1 ft min/max)Web stream11.9 M (Potree octree) Control29 points (nail & tab, iron rod & cap, nail & disk) Horizontal CRSNAD83(2011) Florida East, US ftDTM cell1 ft Contours0.5 ft intervalProject25-00264

Ground elevation: –

Elevation profile

Roadway Topographic Survey: Terrestrial Laser Scanning

A 1.1-mile roadway corridor topographic survey (project 25-00264) captured as five terrestrial laser scanning blocks with almost a billion points, tied to 29 surveyed control points. I reduced, adjusted, merged, classified and modeled the scans into the products a roadway design team uses: a bare-earth surface, contours, slope and drainage analysis, a true-color plan view, a classified 3D point cloud and a control-point QA report, all published to the web with open-source tools.

RIEGL TLSSurvey control (NLTTS · IRCS · NLDF)Python (laspy · NumPy · SciPy)GDAL / OGRCloudComparePotreeConverter · PotreeLeafletChart.js

1 · Scan & control5 TLS blocks along the corridor; 29 control points set or recovered

2 · Reduce972 M raw points → 18.8 M feature-preserving 1 ft min/max cloud (ground, curbs, edges kept)

3 · AdjustPer-block vertical adjustment to control, then density-based block merge (no edge-of-range ghosting)

4 · Classify & modelProgressive morphological ground filter, 1 ft DTM, 0.5 ft contours, slope, ponding

5 · QA & publishControl residual report, map tiles, GeoJSON, Potree octree

Map

True-color plan view rendered from the scans
Shaded DTM, hillshade, slope classes, ponding depth, 0.5 ft contours
Control points colored by QA result, with residuals
Hover elevation, profiles with average grade, distance measure

3D scan

Classified point cloud: ground, vegetation, structures
Spot elevations, distances, heights, areas, angles
Cross-sections across the road and clip boxes

Method & QA notes

Each scan block was shifted vertically to the control points that have a clear ground return, about +6.8 ft for every block, which shows a consistent datum offset in the raw export. Overlapping blocks are merged cell by cell, keeping the block with the highest local point density. Control residuals are measured against the final 1 ft DTM. Points without a clear ground return in the reduced cloud are flagged rather than forced. This is a preliminary QA built on the registration-grade light clouds. A signed PSM deliverable uses the full-resolution adjusted cloud.