vanishing 3d tiles on zooming out

[hardreddata]

Hi,

I noted CesiumGS/cesium#8600 with interest in the latest release.

Is the story below an example of this problem? When I zoom out slightly the red cube disappears, I think also dependent on window size

https://cesium.com/ion/stories/viewer/?id=24df180f-8dbf-4297-b4eb-af881394ce82

The cube is https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/sourceModels/Box/Box.dae

I tried uploading the embedded .gltf example from https://raw.githubusercontent.com/KhronosGroup/glTF-Sample-Models/master/1.0/Box/glTF-Embedded/Box.gltf as 3d tiles but got a tiling error.

Any advice is appreciated.

[lilleyse]

It kinda looks like the tile's geometric error is too low. We'd have to fix this in the tilers. Thanks for opening the issue @RussellGrew.

[OmarShehata]

@RussellGrew have you experienced this issue with any other models?

[hardreddata]

Hi Gents,

Just going through my handful of assets 70921 will vanish completely, but 70924 (far less complex a model) will not. Both of these were shamelessly lifted from Sketchfab.

Thanks for the help.

[OmarShehata]

Just going through my handful of assets 70921 will vanish completely, but 70924 (far less complex a model) will not.

This was answered over support email, but to close the loop here, the issue with that asset was that material was not set to double sided, so pieces disappeared when looking it from the other direction.

This is a different issue from the geometric error being too low for the cube above.

[hardreddata]

Hi @OmarShehata thanks for ensuring this issue is looked at. I removed reference to our CAD discussion from this post.

The two assets you refer to are in this story - the second one vanishes.

https://cesium.com/ion/stories/viewer/?id=69580393-2fdc-4465-80da-78e928bb0f6c

This vanishing issue isn't impacting any of our work. It is more academic.

[OmarShehata]

Thanks Russell! This shows off the issue well, and this definitely seems like a geometric error bug (I love the choice of models here by the way).

[OmarShehata]

We're migrating the issues in this repository to consolidate questions, Cesium ion feature requests, and bug reports on the Cesium community forum, that way there'll be one place to search for answers.

We're tracking this issue internally now. For any follow-up questions, please use the community forum!