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I am exporting simple 3D models as .obj, .fbx or .glb using blender, and succesfully display them in the 3D viewer app of a hololens 2. As soon as the models are more complex (for example created by makehuman), the exports cannot be displayed in Hololens 2 3d viewer app.The error message says that the models are not optimised for windows mixed reality. I found some documentation on the limitation of Hololens 1 .glb files. But I cannot find the specification for hololens 2 and the three file formats.

In addition: Should I reduced the complexity in the blender models, or during the export, or are there even tools to post-process 3D models for Hololens 2 / Windwos mixed reality?

Andi Schroff
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You can use the following link as a guide for optimizing your models - Optimize your 3D models

Carlos Lopez - MSFT
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  • Thank you very much. Even the article has Dynamics365 as scope, the rules seem to apply for the simple 3D viewer in Hololens2. I reduced the number ov triangles from 26K to 8K in Blender before exporting (using the Decimate Geometry Tool) and then displaying in Hololens 2 works!! – Andi Schroff Jan 03 '21 at 18:34
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The asset requirements for pre-installed 3D Viewer app on HoloLens 2, please see Asset requirements overview for more details, here is a quote to the main points::

  1. Exporting - Assets must be delivered in the .glb file format (binary glTF)
  2. Modeling - Assets must be less than 10k triangles, have no more than 64 nodes and 32 submeshes per LOD
  3. Materials - Textures can't be larger than 4096 x 4096 and the smallest mip map should be no larger than 4 on either dimension
  4. Animation - Animations can't be longer than 20 minutes at 30 FPS (36,000 keyframes) and must contain <= 8192 morph target vertices Optimizing - Assets should be optimized using the WindowsMRAssetConverter. Required on Windows OS Versions <= 1709* and recommended on Windows OS versions >= 1803

For the question of other tools to post-process 3D models, you can easily optimize any glTF 2.0 model using the Windows Mixed Reality Asset Converter available on GitHub. This tool includes a command line tool that uses these steps in sequence in order to convert a glTF 2.0 core asset for use in the Windows Mixed Reality home.

Hernando - MSFT
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  • Thank you very much, Hernando. Can the article from early 2018 really apply to Hololens 2? At least the first point is outdated, as beside .glb also .obj and .fbx formats work. Therefore, I was expecting that this information is part of the truth only. Also the github code (from early 2019) seems to apply only to .glb format. I am more familiar with .obj and would like to continue working with this format (which works at least for simple models). – Andi Schroff Dec 30 '20 at 08:30
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From my experience, only the simplest models will successfully open in 3D viewer, whether using HoloLens1 or 2. A primary reason is that even a model that "looks simple" could very well be comprised of well more than 10,000 polygons. For instance, a simple model of a screw, modeled originally in a CAD application, could be 10,000 polygons. So imagine how many polygons the whole product model would be!

ouflak
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Barry C
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