I import an obj file on Cesium. When the model is loaded initially, the 3D mesh looks very good. Upon the loading completion, some noise is found on the top of the layer. Any idea?
Is there anything else going on in the software while you wait for loading to complete? Terrain stuff? If by “noise” you mean the loss of details, that looks like some kind of quantized filtering, but don’t know the source of that. For developers there are a few events you can hook into, loadingTile, etc. that you can try to spit out to the console to see what’s going on.
This is almost certainly not an issue of CesiumJS. It looks like something went wrong with the tiling. If you can share the asset ID, someone from the Cesium ion team might have the chance to take a look at this. (Any further information, e.g. about the input data or configuration settings might be helpful as well).