Prepare the source
Contours are only as reliable as the terrain source. Finish breaklines, boundaries and surface checks before generating the final contour set.
Generate contour polylines
- Run
DTM_Contours. - Press Enter to auto-detect a standard TIN layer, select 3DFACE triangles manually, or choose XYZ objects.
- Enter the contour interval.
- Choose the current drawing colour or colour by height.
- Review the 3D polylines on
DTM-Contours.
Video placeholderGenerate 0.5 m contours from a finished TINShow source selection, interval input and the final coloured contours.
Choose a sensible interval
- Use a smaller interval where subtle grades matter and the source supports that detail.
- Use a larger interval for regional context or a cleaner drawing.
- Do not imply accuracy finer than the scan, survey points or sampling grid.
- Keep major and minor contour styling as a separate drafting step when required.
Image placeholderSame terrain at 0.25 m and 1.0 m contour intervalsUse a side-by-side plan view that makes readability differences obvious.
Read contours as a quality check
Unexpected spikes, loops, sharp corners or contour crossings often reveal bad points, missing breaklines or incorrect triangles. Return to the surface rather than manually disguising systematic errors in the contour output.