STL-Landscape - Iges

Hi there,
I have a srtm-terrain as stl-file and need to export this as iges for cnc milling. How can I achiev this ? The CNC needs a volumentric model but I have no idea how to make a volumetric model form a stl-terrain ?

Meshes are generally used for terrain models because they can better reproduce the “chaotic” nature of natural landforms. There is no automatic way to convert a mesh into a surface/volume without having either expensive reverse engineering software or redrawing it manually using the mesh as a guide.

For a terrain model you could try using Drape to drape a surface over the mesh - you will lose some detail depending on how “textured” the mesh is, the NURBS surface will smooth things out - but it might be OK for what you need.

The best way of course is to find a production shop who can use the mesh directly for machining.


Any CNC should be able to mill meshes, but if you really have to convert it then you can use the mesh to nurbs command unless the mesh has too many faces. Or use drape if it doesn’t have to be too accurate.

CNC’s only use G-Code. It’s the CAM software that can either accommodate mesh formats or not. There are still a few notable CAM packages out there that cannot do meshes, and lots of machine shops do not update their CAM software that often (it’s expensive).

My suggestion is always to find an architectural modelmaker who is CNC-equipped - in general they will be used to working with meshes.


Drape works fine. But when intersecting the terrain with a box I have bad results. On the left the result after intersecting and on the right before.

What CAM software are you or your machinist using?

That’s odd. Cutting the drape surface with the box shouldn’t change it at all, just trim it.


You’re right, I’d just check if it’s the rendering mesh that’s looking bad.

Thanks, seems as it was the rendering.

How can I increase the “resolution” of the drape. My Model is about 1200 x 3250 mm. But the drape only has in U about 160 and in V about 360. What is limiting ?

S[quote=“Clemens_Mark, post:10, topic:31817”]
But the drape only has in U about 160 and in V about 360. What is limiting ?

Set Autospacing to No, then you will get options for U and V in the command line. The max number of points in both directions is 847… It will let you set more, but it simply truncates the number behind the scenes without telling you. If objects are relatively small, it may also limit the number of UV spans…


There’s another approach. Make that box a mesh box and try one of the meshBoolean command, there is split, intersection or union you could use. You don’t need two closed meshes to do that, you can use the terrain mesh as a cutting ‘plane’, just play around with the normal direction using ‘flip’