Question about 3D Tiles and the CESIUM_primitive_outline extension


As I’ve understood it (correct me if I´m wrong) it should be possible to activate outlines for 3D Tiles using the CESIUM_primitive_outline extension. I’m not sure however how to make this work. Does the tileset need to be prepared in a certain way?


Hi @eriblan,

Just to confirm, the models in your tileset already include the CESIUM_primitive_outline extension, correct? The showOutline option will have no effect on tilesets / models without this extension built into their glTFs.

If they do contain the extension, then do you have a Sandcastle, if not a sample model, that replicates what you’re seeing?

Hi,thank you for the reply.
The models in the tileset does not already include the extension. I think the question is about if the extension also could be applied to Cesiums other 3D tiles formats (like b3dm), I suppose it can´t.
Or if there is another simple way of creating outlines for those other formats.

Overall, I´m a little bit confused by the different formats and the nomenclature used in some places :slight_smile:

Hi @eriblan,

Yes, the extension can also be used in other 3D Tiles formats, provided that they are formats that contain glTFs. Batched 3D Models and Instanced 3D Models are two such formats; both of them contain glTFs with some other data for features / instancing respectively.

As an example, Cesium OSM Buildings is a tileset containing b3dms, each of which embeds a glTF with the CESIUM_primitive_outline extension. You can also use tilesets containing pure glTF content (via the 3DTILES_content_gltf extension), and if those glTFs have the outline extension they should display. Support for this is already in main, but will be officially shipped in the CesiumJS 1.97 release.