2024 Optimize Export stacks the positions of duplicate geometry once imported into Unity

[shayne.kiekebosch]

FYI this is more of a letting others know rather than we need this problem fixed since we developed a little workaround in our Navisworks plugin.

We have an application that uses the Unity Engine with FBX models exported from Navisworks. This issue only appears when the model is exported from Navisworks 2024 with the Optimize Export option checked. I believe that this optimizing does something to the positional data of objects where there are multiples of them that Unity can't seem to handle properly.

A simple example would be a building with a lot of chairs inside. The chairs would be using the same geometry. When Optimize Export is un-checked for the FBX export from Navisworks, everything will be where it should be once imported into Unity. When Optimize Export is checked for the FBX export from Navisworks, all the chairs will be stacked in 1 position making it look like there is only 1 chair and all the rest are missing once imported into Unity.

[s.hamel]

I'll add some background to this as well. The FBX file format supports instancing of geometry, which can significantly reduce file size, e.g. the chair you mentioned has the same geometry for every instance, so why include hundreds of duplicative entries for that geometry vs a single instance which is used by all. Unfortunately Unity doesn't support this instancing on their side when the file is read in, so you end up with the scenario outlined above. So an option was added to Navisworks allowing this instancing to be turned off. Hopefully Unity will add FBX instancing support in a future release, as it can have a dramatic affect on file size and load times.

And lastly, always good to meet another Shayne :).