Ive applied the raster overlay to OSM buildings but it is super blurry, how do i increase the resolution?
Have you tried decreasing the “Maximum Screen Space Error” on the overlay?
Yes that does help. But Is it possible for it to have the same quality as a raster overlay on terrain?
And sometimes the raster overlay doesnt even show on some buildings
We can help you more if you provide visuals of what you’re seeing, as well as details to reproduce it. For example, what overlay are you using to drape on OSM buildings? What terrain are you using? What does it look like on OSM buildings vs. on terrain? What does it look like when the raster overlay doesn’t show on buildings?
The more details and screenshots, the better 
I’m using cesium world terrain and bing maps from cesium ion. When the raster overlay is not rendered on buildings, the buildings are usually large and they are dark green. Large buildings are the only buildings that are affected. By large buildings I mean buildings which are larger in base rather than height
This is unfortunately a known limitation with tilesets like Cesium OSM Buildings. I wrote an issue for it:
Is it possible to fix the issue with some buildings not having texture?
I don’t why that would happen. More likely the color of the low-res texture over some buildings is just grey or whatever, so it looks like it’s untextured. But if you disagree, please share a screenshot.
The area you’ve circled in red is textured, it’s just a low-res texture. So that’s the problem described in the github issue I linked above, and there’s unfortunately no workaround currently.
It’s harder to tell with the buildings you’ve circled in green. Those do look vaguely untextured. But I don’t know of any reason that those buildings in particular would be missing a raster overlay, so I suspect the Bing imagery just has a rather uniform greyish color there. You can confirm by toggling the OSM Buildings off to see what the imagery looks like underneath.
On bing maps, the untextured buildings are pure white. Don’t know why it’d show as green though. This issue happens elsewhere too but it only happens for buildings with a large base.
Large buildings are going to be textured by a very low-res version of the Bing imagery. So it’s likely that the zoomed out version of the Bing texture is green in that area.
Okay. Thanks for the answer!