Preparing Meshes for Import to Revit as DirectShape

statue-fixed in Reivt

This article answers the most common problem customers have when using my Mesh Import from OBJ files app. That app makes Revit elements that are called DirectShape from meshes. A DirectShape may only be made via Revit’s API or other programming methods, not its user interface. The data that may be contained in an OBJ file are much looser than a DirectShape in Revit can hold. The main qualities that are needed when creating a DirectShape are that the mesh is manifold (one continuous surface), and under about 150000 faces. Often, a mesh created by photogrammetry has particles and holes that make it non-manifold. There can also be millions of faces that need to be reduced (decimated).

ReCap Photo is the best app I have found for decimating and fixing meshes. There are other mesh editing apps like MeshLab & ReMESH that may be able to do similar things but are harder to use. More alternatives listed at meshrepair.org.

Mesh Repairing Example 1

This beautiful mesh came from The Meon Survey Partnership Ltd.

Viewing in MeshLab, I can see it has over a million faces and visible particles.

The Fixes

I used ReCap Photo.

I had to decimate the mesh to under 150K faces.

I checked its integrity, too. That is to remove all particles and holes. Holes can be filled flat or smooth. I prefer flat.

Here it is imported to Revit with my Mesh Import app:

Mesh Repairing Example 2

The OBJ:

This was the error message when importing to Revit:
The mesh was okay for the number of faces, but needed to be manifold. I fixed it with Autodesk ReCap Photo.
I did the Diagnostics command and removed particles and holes:

An OBJ can have any kind of units, its vectors are just numbers in XYZ. This is what the file looks like. I guessed its units were meters.

These were the import options I chose in my app:

Units Meter, Category Site, Z to the South means “Y-Up”

Hence, it came into Revit:

Display

The customer asked if he could get rid of, or lighten, the mesh lines. I suggested:

One way is to turn off Show Edges in view:

Another way is to override the Projection Lines color of element:

The app is available for $50 at https://apps.autodesk.com/RVT/en/Detail/Index?id=7847254631022872970&appLang=en&os=Win64