Contours (DTM / TIN)
SDBox Design Software - Command guide for calculating and drawing contour lines from triangles (3DFACES) in CAD drawings
Contour Lines
DTM & Boundaries
3D Terrain
Workflow Overview DTM
Contour calculation and drawing from triangles (3DFACES).
After you create a TIN (triangulation) from your survey points, you can calculate and draw contour lines as either temporary contours for checking, or final contours for production drawings.
Before drawing contours, it is strongly recommended to run basic triangle checking / cleanup commands to avoid gaps, duplicates, and invalid geometry.
Recommended pre-checks (before contours)
- TTH: Shade triangles to detect areas where triangulation is missing.
- ZTTDBL: Delete duplicate triangles.
- ZTTKK: Detect zero-area or vertical triangles (review and delete/modify if needed).
- ZTTSD: Detect problematic cases where more than two triangles share the same edge.
Typical contour workflow:
- Select triangles and create temporary contours to review the result in the drawing.
- Create final contours. You can delete and redraw them any time after edits.
- Optionally smooth contours (and remove smoothing if you need to revert).
- Add elevation labels on major contours or as single elevations where required.
Contours module
^ Back to topTemporary Contours (Calculate + Draw) IIJ
Calculates and draws temporary contours from selected triangles.
On the first run, you select triangles and define a contour interval. On subsequent runs, the command recomputes the temporary contours using the previously selected triangles, incorporating any triangle edits performed with SDBox triangle-editing commands.
What you do
You do nothing while the command calculates and draws the temporary contour lines.
Notes:
Two types of temporary contours are created: major (typically each 1.00 unit, shown in red) and minor (shown in green).
You may use any contour interval (even very small values). The command is designed to remain stable in both calculation and drawing.
Command Usage:
Use IIJ whenever you have edited triangles and you need updated temporary contours before proceeding to final contours (ZDTMISO).
Tips:
After running IIJ once, use IIJK for very fast redraw during zoom/pan inspection. It produces the same temporary contour geometry without repeating all computations.
For inspection, you can toggle visibility of triangles with TTV and similarly toggle points (if available) with SSV.
Temporary Redraw (Fast) IIJK
Fast redraw of existing temporary contours.
This command redraws the temporary contours quickly (without repeating the full computation), making it ideal for contour inspection while you zoom/pan through the drawing.
What you do
You do nothing while temporary contours are redrawn.
Tips:
After you run IIJK once, you can often refresh the temporary contours after a zoom/pan simply by pressing Space, allowing rapid visual QA of the contour network.
Recompute Temporary Contours (Reselect + Interval) IIJR
Reselects triangles, sets contour interval, then recomputes and redraws temporary contours.
Use this command when you want to change the contour interval and/or the triangle selection that participates in temporary contour calculation.
Select objects:
Notes:
IIJR resets all options used for temporary contour workflows and is typically slower than IIJK, because it includes selection and full recomputation.
Final Contours ZDTMISO
Draws final contour lines ready for production drawings.
If you previously used temporary contour commands (IIJ / IIJR), this command uses the current triangle state and your defined interval to generate final contours. After final contour drawing, you may delete and redraw contours at any time, especially after triangle edits.
Command Usage:
Run ZDTMISO only after you have verified the temporary contour result and completed triangle corrections. This ensures final contours reflect the validated TIN.
Smooth Contours IP2S
Smooths contour lines to improve cartographic appearance.
Smoothing is typically applied after final contour drawing when you want more visually continuous curves. It is recommended to keep an unsmoothed state available (or be ready to remove smoothing) if you need to make engineering corrections later.
Tips:
Apply smoothing after your contour set is stable. If you expect further triangle editing, delay smoothing until the end to avoid repeated cleanup.
Remove Smoothing IP2L
Removes smoothing and restores contours to their pre-smoothed geometry.
Use this command when you need to revert smoothed contours back to a more “original” computed state for editing, QA, or corrections.
Label Major Elevations on Straight Segments SSA
Writes major elevation values on contour lines along straight portions.
This command is used to place readable elevation labels on major contours, typically aligned to straight sections for improved clarity in printed drawings.
Major elevation labeling on contours
Command Usage:
Use SSA after final contours are confirmed, so labels remain consistent and do not require repeated cleanup.
Label Single Elevations SSAS
Writes individual elevation labels where you choose.
Use this command when you want to place elevation labels at specific locations instead of automated major labeling along straight segments.
Single elevation labeling
^ Back to topOpen / Close Contours IIV
Opens or closes contour polylines according to your selection.
This command is typically used to manage contour closure behavior for presentation or for specific drafting requirements.
Notes:
If a contour should remain closed but appears open (or vice versa), review the underlying contour geometry and nearby intersections before forcing closure.
Bulk Delete Contours ZEEISO
Deletes contour lines in bulk.
Use this command to remove existing contours (temporary or final, depending on your workflow) so you can redraw them cleanly after triangle edits or design changes.
If the command requests object selection using filters, use the standard SDBox filtered selection tool:
Filtered object selection
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