search

CesiumGS / 3d-tiles-tools

Apache License 2.0
315 stars 47 forks source link

Implement LOD grading for tiles #116

Closed jingyangking closed 7 months ago

jingyangking commented 7 months ago

Hello developer, during the process of converting OBJ to til image es, can we achieve LOD grading for b3DM, just like in the image

javagl commented 7 months ago

The 3D Tiles Tools do not involve any functionality for converting OBJ to 3D Tiles.

Did you mean to open this issue in a different repository?

jingyangking commented 7 months ago

The 3D Tiles Tools do not involve any functionality for converting OBJ to 3D Tiles.

Did you mean to open this issue in a different repository?

Sorry, this was my negligence. However, if I were to perform LOD on tiles, I think it would greatly reduce the rendering pressure. Therefore, I want to generate corresponding LOD levels while generating tiles. However, I currently do not have a good idea. Do you have a good method for this? Looking forward to your reply! Thank you!

javagl commented 7 months ago

Your image shows the LOD-0, LOD-1, and LOD-2 directories, and a tileset.json.

What do the directories and the tileset JSON actually contain? It looks like this already is a tileset with different LODs.

Or do you want to convert an OBJ file into a tileset that has this structure?

jingyangking commented 7 months ago

This is an empty file I created. The image is just an example and has no actual content. My goal is to quickly load a BIM model that exceeds 1GB on the web side, so I want to combine tiles with LOD to significantly reduce rendering pressure, thereby improving the loading speed and smoothness of the model. So, while converting the model (obj/fbx/glb/ifc) to tiles, perform LOD on it, which is very close to my goal. The image example I showed is like what you said, converting the model to something similar to the one in the image. If you have any good ideas, please let me know. Thank you very much!

javagl commented 7 months ago

I see. There are several tools that claim that they can convert models (like OBJ files) into 3D Tiles. But when it comes to large models, like 1GB, and you want the result to have a structure of LODs that is good for streaming and efficient visualization, you'll need a proper tiler.

Cesium ion offers dedicated tilers for CAD models, and when you upload the model in one of the supported fromats, then it will create an optimized and tiled representation for it. You can also make the result available for download, and eventually download the 3D Tiles data in a structure that is likely similar to the one that you suggested in the screenshot.

jingyangking commented 7 months ago

Thank you for the method you provided. I will try it out.

javagl commented 7 months ago

If you have any questions about Cesium ion, the upload, functionality, or the results, feel free to ask them in the community forum at https://community.cesium.com/c/cesium-ion/9

jingyangking commented 7 months ago

Of course, I will. Thank you for providing a place for discussion.