What the deviation map measures
DTM_DeviationMap samples the difference between the TIN and nearby point-cloud data. Red marks cloud points above the surface, blue marks points below it, and green indicates close agreement.
Create the quality map
- Run
DTM_DeviationMap. - Select the TIN or press Enter to auto-detect it.
- Set a noise threshold to reject distant returns such as vegetation or vehicles.
- Set the heatmap grid resolution.
- View the coloured 3DFACE cells on
DTM-Deviationin a shaded visual style.
Video placeholderCreate and inspect a terrain deviation mapShow threshold and grid inputs, then orbit around red, green and blue areas.
Interpret patterns, not isolated pixels
- Broad red areas can indicate a surface below the actual ground or unfiltered objects above it.
- Broad blue areas can indicate an over-smoothed or elevated surface.
- Linear bands often point to missing curbs, channels or ridge breaklines.
- Scattered extreme cells usually indicate scan noise or an unsuitable threshold.
Image placeholderAnnotated deviation map with four common error patternsLabel missing breakline, vegetation, boundary issue and good-fit area.
Correct and repeat
Return to the source points or breaklines, correct the terrain, rebuild the affected area and create the deviation map again. Record the threshold and grid resolution so comparisons between revisions remain meaningful.