How to Use Direct Modelling on TIN Surfaces in BricsCAD
Quick answer: This covers a different set of tools from the solid-modeling Direct Modeling commands covered elsewhere in this hub (EXTRUDE, DMFILLET, and so on). Here, TINEXTRACT pulls solids, meshes, points, faces, contours, and borders out of a TIN surface, TINMERGE combines multiple TIN surfaces into one, and TINMODIFY deforms or smooths an existing surface.
Extracting Entities from a TIN Surface
TINEXTRACT generates a solid, mesh, border, intersection lines, faces, or points from a TIN surface, useful for exchanging that geometry with other applications for further analysis. Solids or meshes can be created as a vertical offset of the TIN surface, as a model between two TIN surfaces, or as a model between a fixed elevation plane and the TIN surface.
Select the TIN surface and run TINEXTRACT to open the Extract From TIN Surface dialog, then:
| To extract | Do this |
|---|---|
| A solid (Elevation method) | Set Solids/Meshes on, tick Elevation, set a height value, click Extract |
| Points | Tick Points, optionally choose a layer, click Extract |
| Faces | Tick Triangles, optionally choose a layer, click Extract |
| Contours | Tick Major contours and Minor contours, optionally choose layers, set the interval for each, click Extract |
| A border | Tick Borders, optionally choose a layer, click Extract |
Merging TIN Surfaces
TINMERGE combines a base surface with one or more other surfaces. Which surface you choose as the base matters: the merging surface always replaces the part of the base surface it covers, so choosing a different base produces a genuinely different result, not just a different starting point.
- Run
TINMERGE. - Choose the base surface.
- Choose whether to keep or delete the original surfaces.
Modifying a TIN Surface: Deform vs Smoothen
TINMODIFY offers two operations: Deform adjusts the surface to follow the contours of an area you define, while Smoothen levels a selected area through interpolation.
Deforming a TIN Surface
Every deform method shares the same basic pattern: select the TIN surface, run TINMODIFY, choose Deform, then pick how to define the affected area. After that, you choose an elevation height, decide whether the result becomes a new element or modifies the existing TIN surface (typing N keeps the original structure intact and adds a separate new surface instead), and can keep clicking additional areas or press Enter to finish.
| Method | How the affected area is defined |
|---|---|
| Radius | Choose a deformation radius, then click the area to deform |
| Specify Contour | Pick an existing contour directly on the TIN surface |
| Select Entity | Type E, select a closed entity (a polyline, for example), then choose an offset distance and click the area to deform |
| Draw Polygon | Draw a polygon and press Enter to close it, then choose an offset distance and select the area to deform |
Smoothening a TIN Surface
- Select the TIN surface and run
TINMODIFY. - Choose Smoothen.
- Choose a radius (the Select Entity and Draw Polygon variants work the same way as their Deform equivalents from this point on).
- A preview of the result displays.
- Click to execute.
- Click other areas to smoothen further, or press Enter to end.
Frequently Asked Questions
Does choosing a different base surface in TINMERGE just change where the merge starts? No, it changes the actual result. The surface being merged in always replaces the portion of the base surface it covers, so a different base produces a genuinely different outcome.
What’s the difference between Deform and Smoothen in TINMODIFY? Deform adjusts the surface to follow the contours of an area you define. Smoothen levels a selected area by interpolating across it instead.
If I choose to create a new element instead of modifying the surface directly, what happens to the original TIN structure? It stays untouched. The adjustment gets added as a separate new TIN surface rather than altering the original.
Why is the extraction option called “Triangles” if the result is described as Faces? That’s simply the label used in the Extract From TIN Surface dialog for what produces face entities; the option name and the resulting entity type use different terms.