Buggy texture coordinate generation for raster overlays

[j9liu]

Originally posted on the community forum. The sample data is linked in the initial post.

TL;DR, raster overlays are not being draped correctly over the provided tileset. It was initially observed when using Cesium Polygon Raster Overlay, but I found some weird behavior using Cesium Ion Raster Overlay as well.

I haven't completely pinpointed the source of this bug, but I have a decent guess that it has to do with the texture generation for raster overlays. For instance, take this area of Bing Maps imagery that the tileset will appear over. When it's draped over the tileset, I'd expect the images to line up on the top of the buildings. But it doesn't do that; they only appear green.

Original	Draped on Tileset

So something seems off. Not sure if there's something unique about the tileset, or if we're making an assumption during texture coordinate generation that this case isn't meeting.

[j9liu]

This problem is coming up again for a different user's tileset as well: https://community.cesium.com/t/does-uploading-a-3d-tile-to-ion-change-the-mesh-at-all/39058/16

[kring]

The second community forum thread linked above turned out to be a problem with the tileset, not a problem with Cesium for Unreal. I've posted a message in the first thread to see if it might be the same situation.

[j9liu]

I'm going to close this for inactivity. It's pretty likely that there's something with the data itself, but no response on that thread unfortunately.