ModelExperimental - Rendering Buildings



I need some help - concerning ModelExperimental.

Can anyone explain the rendering of the buildings ?

Are the colors depending on the time - is there a flag to switch the rendering ?

Is there a way to turn of the sun-based lighting, like Right combination for turning off sun-based lighting?


Hi @Ruediger_Brand,

By default, CesiumJS has a single light source, the Sun. As the timeline advances, the sun moves, and so does the light direction in the shader.

Are you trying to make the lighting constant even if the timeline moves? If so, consider setting scene.light to a DirectionalLight. This is the only other light source type supported in CesiumJS besides SunLight (the default).

If you don’t need an animated timeline, you just want consistent lighting, you could also try setting a specific time on the timeline. For example, in this sandcastle there’s a line here that fixes the timeline and therefore the sunlight direction:

viewer.clock.currentTime = new Cesium.JulianDate(2457522.154792);

If you need more assistance for your use case, are able to share a Sandcastle link to this example and more information about your desired results?


Hi Peter @ptrgags,

I was wondering because these effects appear the first time I use ModelExperimental - is there another default comparing with the standard model, not setting ModelExperimental ?




Default ModelExperimental true

The screenshot is done at nearly the same time - are there different default styles ?

Where can I find them ?

In your sandcastle I didn’t see any differences using modelExperimental or not ?


I don’t know if it helps, but in the sandcastle

I have similar effects setting ModelExperimental or not.

Hi @Ruediger_Brand,

Thank you for the Sandcastle link. It looks like Cesium OSM Buildings aren’t rendering properly for a couple reasons, I opened Rendering issues when rendering OSM buildings with ModelExperimental · Issue #10338 · CesiumGS/cesium · GitHub to track this.

Also, which version of CesiumJS are you using? Image-based lighting support was added to ModelExperimental in one of the recent releases, that sometimes makes a difference in brightness. That said, if a style is applied here, it could be something else.


Hi! I also encountered a problem where it seems that GLTF payload from tilesets does not show any ambient lighting. The surfaces where sun does not hit are totally black. Without model experimental toggled on we can see ambient light of about 20-30% even if sun is not hitting some surfaces.

I am wondering how should one control the amount of ambient light in Cesium scene in general with the model experimental?


I use the version 1.91


@ptrgags Hi Peter,

I have also some arifacts rendering polylines


See the white part on the lines…

Is this a similar error ?


Hi @v12424124_34 and @Ruediger_Brand,

Are either of you using Cesium 1.92 or 1.93? Image-based lighting was not added to ModelExperimental until Cesium 1.92, so if you’re using an earlier version of Cesium it makes sense that the models would render darker. If the problem persists after switching versions, though, do let me know.

As for the polyline rendering artifacts, those shouldn’t be related to any features in ModelExperimental…could you provide a Sandcastle that reproduces this error?