Landscape workflow - drape / project

I am trying to streamline workflow. I thought that I could import a 2d cad drawing, paint the landscape with materials then project or drape that 2d landscape over my 3d terrain.

When I did so, I was able to drape the 2d cad landscape layout reasonably successfully, but for a few touchup and I was quite pleased.

I was hoping the colors would transfer too but they did not.

I went on to try to project the materials to the 3d model but this appears to only work with pictures / images.

I wanted to use the materials and not images, as once the 3d model was complete, I would use the materials in a 3d renderer.

I have previously hand applied materials to the 3d terrain model but this takes time and the more complex the model the more time it takes. I was especially looking to reduce that step so I could quickly update the model with changes this way.

Does anyone have any suggestions on how to improve the workflow and/or project multiple materials from a 2d model to a 3d one?

As you’ve noted already, only edges, not surfaces or materials can be ‘draped’ onto a terrain. Moving forward, make sure to leave your 2D CAD linework as just that, lines or uncolored surfaces only and after draping, begin the coloring/ material process.

See example of my workflow. Everything comes in as 2D and is placed directly above the 3D terrain…and piece by piece, as needed, I bring it down onto the existing or proposed terrain group.

I then use simple colors to fill in the surface areas and then ‘group by material’ and assign color groups (ie road, sidewalk, planing, lawn, water…etc) to their respective Tags. This grouping and tagging process speeds up material replacement for rendering later which is why not a lot of thought needs to go into the materials at this point.

A similar process applies to other objects that sit on the terrain’s surface…such as furnishings, trees, and buildings. They are brought in and aligned above the terrain and ‘dropped’ instead of draped onto the surface below.

Again, the short answer is no. If you have materials applied to a 2D surface you’ll have to sample and (re)paint them to your 3D surface.