LOCAL GROUND EXTRACTION
Ground Desk
From an unclassified cloud to a ground surface you can inspect.
ON YOUR DESK
LAS + LAZ · BROWSER ONLY
Ground review
Wheel zooms at cursor; drag pans. Focus map for +/−, arrows or Home (Fit). Buttons provide click alternatives.
Open your cloud to start a local ground extraction.
Inspect
the confidence map before exporting.
Extract ground to prepare local review.
Checkpoint markers
Import checkpoints to show residual markers.
Red: surface high; blue: surface low; neutral: zero or unmeasured. Filled circle: evaluated; hollow: no-data; X: excluded; diamond: unmapped; square: invalid. Signs and statuses appear below; no individual ASPRS pass/fail.
No checkpoint selected.
A relative confidence score, not a probability of correctness. Dense vegetation, roofs, steep terrain and missing ground returns need review.
Survey result
The classified cloud keeps all original records. Noise is marked and excluded from ground products.
Classified LAS · thinned ground LAS · LandXML grid TIN · ASCII ground DEM · confidence PNG + world file · processing report
Independent checkpoint report (optional)
Import P,N,E,Z,D CSV; D is Description. Independent checkpoints validate the exact exported surface and never change classification.
Description code guide
D chooses the assessment pool and optional project criteria. It never changes elevation, classification, smoothing, fitting or the global ASPRS class. Residual = final exported LandXML TIN elevation minus surveyed Z at native E/N, converted to cm. Output smoothing, if enabled, is included.
| Exact code | Surface | Assessment pool |
|---|---|---|
| ASPHALT / CONCRETE | Hard / paved | NVA |
| BARE | Bare earth | NVA |
| SHORT_GRASS | Short grass | NVA |
| TALL_GRASS / BRUSH / FOREST | Vegetated | VVA |
Example P,N,E,Z,D:
101,9980712.50,3302388.50,350.25,ASPHALT.
Coordinates use your declared native survey units.
Guide application trims spaces and ignores case for exact codes only. GRASS, partial codes, blank and unknown descriptions remain unmapped. Import assigns nothing automatically; your original CSV descriptions stay in the audit.
One global pooled NVA combined-RMSE target applies; combined RMSE = √(residual RMSE² + documented checkpoint survey RMSE²). VVA combined RMSE is as found. Optional per-description NVA combined-RMSE or VVA absolute-error P95 limits are project diagnostics, not separate formal surface tolerances. Individual absolute-error tolerance never automatically excludes a checkpoint. Unknowns and no-data need audit review. No guide numeric defaults are supplied.
Import CSV, then explicitly apply the guide or map descriptions yourself.
No checkpoints loaded.
ASPRS 2024: pooled NVA uses combined RMSE; VVA is reported as found. At least 30 checkpoints per applicable assessment. Larger areas recommend more NVA checkpoints. Description limits below are optional project criteria, not ASPRS point classes; blank means as found.
| Description | Surface category | Project group limit cm: NVA combined RMSE / VVA P95 | Optional individual tolerance cm | Description exclusion reason |
|---|
Sampling, bias and row-review declarations
Unchanged NVA residuals above three targets prevent a formal statement. Investigation notes retain residuals; corrected source/checkpoint data must be recalculated or an exclusion justified.
Optional reviewer details (unsigned)
All three are included in the survey ZIP. Every row, exclusion, invalid value and no-data result remains auditable. The blank signature block is unsigned. This is exported-surface vertical assessment, not cloud accuracy or full ASPRS/3DEP certification.
Method and limitations
An adapted cloth simulation uses spatially thinned lower-envelope seeds. A global affine terrain trend is applied only when its elevation change over cloth spacing exceeds ground tolerance. Valid last returns are preferred. Low noise and isolated outliers are marked first, then all eligible original points are checked against the accepted model.
Only supported cells appear in the DEM. Adjacent occupied cells form the XML TIN; gaps are left open. Confidence combines local ground density, neighboring support, cloth residual and actual cloth collision support. Output smoothing is separate from cloth processing.
This first version requires field validation against checkpoints. It is not a certified survey result. Read the method · Operating notes