I’ve been able to achieve this, but it’s fairly complicated!
Main Problems…
- Although the vertex information is stored in a (non binary) .obj, the material definition of is stored as a separate .mtl/image file.
- Even if you get hold of the colour information, the API doesn’t allow you to define render appearance colours for materials ***EDIT - The Revit 2018.1 API now does - http://thebuildingcoder.typepad.com/blog/2017/08/revit-20181-and-the-visual-materials-api.html
Solutions…
- Using Meshlab you can open the obj and essentially “bake” the colour information from the texture image onto the mesh. If you then export the mesh as a non binary PLY this gives you a text file containing a list of vertices (as XYZs) and their colours (as RBGa values), as well as a list of vertex triplets for creating mesh triangles.
By slicing up this text file in the right way using dynamo you can derive all the geometric and colour data you need to recreate the mesh. You could create surfaces in dynamo and import a direct shape but I had better results using an adaptive component family.
- Solving the render appearance issue was much more long winded. As it’s not possible to define the render colour using the API my solution was to ensure I had a materials library of as many colours a possible and devise a way to match the colours defined in the data to the nearest one in my library.
I started by creating a RAL colour material library (it seemed as good a set of colour as any), and from some previous work I knew that the best way to find the closest RGB value from a set list is to convert RGB values to XYZ values, creating a set of points and finding the point which is closest the input point.
As you can imagine there’s a fair amount of processing involved, so I tend to run 3k faces at a time.
Here are a couple of examples of meshes of people I’ve created using photogrammetry an turned into Revit families using this process
You can also use a similar technique to import point cloud data (best to reduce the density first in something like cloud compare) as fully renderable objects…
