model distorted in different draco compression rates

1. A concise explanation of the problem you’re experiencing.

I’m using draco-compressed gltf model in my project. It works fine in the following parameters during the compression process:

sOpt.pos_quantization_bits = 14;
sOpt.tex_coords_quantization_bits = 12;


But after I set the bits higher like below:

sOpt.pos_quantization_bits = 20;
sOpt.tex_coords_quantization_bits = 15;


The model distorted in Cesium.

The same model can be normally displayed in Babylon.js.( upper: Babylon.js; lower: Cesium.js )



2. A minimal code example. If you’ve found a bug, this helps us reproduce and repair it.

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

I need to use smaller model in out project, because the original model is too large.

4. The Cesium version you’re using, your operating system and browser.

Cesium 1.51

Windows 10

Chrome 71.0.3578.98

This is interesting. Can you share the compressed model (and perhaps the original model as well) so I can try to reproduce this? You can upload it somewhere or just email it to

Thanks Omar,

Sorry, I can’t get the original model currently, Here is the distorted model.

在 2019年1月4日星期五 UTC+8下午9:09:11,Omar Shehata写道:

3e3076dd-4fa9-4741-a2be-0407a3a9af98_0.gltf (5.59 KB)

3e3076dd-4fa9-4741-a2be-0407a3a9af98_0.lbbin (43.1 KB)

Thanks for providing the sample model Chris. I think this might be due to CesiumJS’s decoding assuming a fixed value for the quantization number. I opened a bug report for it here: