Sometimes when compiling a level for Source you'll get a message like this in the compile log:

Found displacement edge abutting other edges

Normally you can ignore this message. It's usually just informative. However, it is a good idea to remove the cause of these messages. Generally, it means you have some displacements in your scene that you didn't know about.

This can happen when more than two displacements have edgest that line up in the same space. Normally there should only be two displacements ever sharing the same edge in space.

Below is a graphic demonstrating a way you can create this scenario.

The solution for this is to delete the displacements that were generated by the two faces of the original boxes that were facing each other (the displacements between the two boxes).

Hints

• When creating displacements from objects in the scene, it's best to add a Poly Select modifier, go to Polygon Sub-Object mode and only select those sides you want to create displacements from--then run the function Create Displacements From Selection.
• If the displacements you want to delete are part of a Sculpt Mesh, you must first Revert the sculpt mesh to displacements. Deleting a displacement that is part of a sculpt mesh will completely invalidate the sculpt mesh.