Tiled 3D model - B3DM not compliant to 3d tile specification

Development Asset Creation
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1

Hi,

I am testing 3d tile export from RC.

It appears that the .b3dm files generated are not compliant with the specification, in particular the file does not start with the correct magic number (“b3dm”).

Can you help?

Thanks

2

Hi andrea.baldacci, the file is compressed by GZip. When you extract files by 7-Zip, then you will get the valid B3DM file with a wanted header.

There is an example, how to set NodeJS server to automatically decompress those files: https://github.com/CesiumGS/cesium , file server.cjs, function checkGzipAndNext.

3

Thanks.

 

4

Sure, I can help you with this.

The B3DM file format is a specification for storing 3D tiles. The file format starts with the magic number “b3dm”, which is a 4-byte sequence that identifies the file as a B3DM file. If the file does not start with the correct magic number, then it is not a valid B3DM file.

There are a few possible reasons why the .b3dm files generated from your RC export are not compliant with the specification. One possibility is that you are using an older version of the RC exporter. The B3DM file format has been updated several times, so it is important to use the latest version of the exporter.

Another possibility is that you are using a different 3D model format in your RC project. The B3DM file format can only store certain types of ready 3D models. If you are using a model format that is not supported by B3DM, then the exporter will not be able to generate a valid B3DM file.

To fix this problem, you can try the following:

  • Make sure that you are using the latest version of the RC exporter.
  • Check the 3D model format that you are using in your RC project. Make sure that the format is supported by B3DM.
  • If you are still having problems, you can try posting a question on the Unreal Engine forums. There are many experienced users who can help you troubleshoot this issue.

I hope this helps!