The model appears, but there are no colors or textures. I used 3dtile.exe to convert the osgb format to the b3dm format file.
It may be necessary to provide more information here. If this question is about “Cesium For Unity”, then it might be moved to the “Cesium For Unity” section. If it is about possible errors in the tileset data, then it may remain in the “3D Tiles” section, but it’s hard to say what is wrong, without knowing the exact input data, the exact tool that was used for converting it, and the exact output. (For example: I don’t know if the “3dtile.exe” that you mentioned properly handles textures and materials)
So if I want to use the osgb format file, is there any tool that can convert it to b3dm?
There seem to be several tools that claim that they can convert OSGB to 3D Tiles, but I can not give a specific recommendation here. (And I would not run an arbitrary executable, unless I can compile it on my own, from source).
Which tool did you use for the conversion?
Do you have the possibility to convert that data into one of the formats that are supported by Cesium ion?
Mainly because my file is a bit big, it is best to convert it. If you convert to other formats, do you have any recommended tools or tools you are using?
Depending on what the original format is (or which other formats the file can be converted to), you could try to upload it to Cesium ion, in one of the supported formats. This should convert the data into 3D Tiles, and retain any textures and materials that are present.