Curious what direction you guys were thinking of for handling holes. The first idea I had was a custom collector. But really filtering on the quad seems like the common use case here. And collectors don't support additional filtering in a generic way that I can see. And I'm not sure it would have other uses outside of terrain if they did. Another approach seems to be maintain a holes array that you can index into like heights. Maybe a bit packed byte array to reduce the size. So far this seems to me like the best option. Keeps it all encapsulated in the terrain logic and would be fairly straight forward to implement.