Skip to content

Asset Compatibility and Workarounds

Overview

This document covers assets that work well with the glTF Importer for Maya and provides practical solutions for common import challenges.

What Works Well

  • Standard glTF 2.0 Compliant Files: Assets that follow the Khronos glTF 2.0 specifications import reliably
  • Geometry and Materials: Meshes, PBR materials, and textures import correctly
  • Animations: Transform animations, skeletal (rigged) animations, and blendshape animations are fully supported
  • Standard Exporters: Files from widely-used glTF exporters (Blender, Maya/Babylon, etc.) are well-supported

For Sketchfab Assets with Rigged Animations

If you experience deformation accuracy issues with auto-generated Sketchfab assets:

  1. Ensure Import Skin Binding is enabled: Rigged assets require skin binding to be imported.
  2. If Issues Persist: Use the Blender preprocessing workflow below to normalize the rig/export.

Alternative Blender Preprocessing Workflow

  1. Import into Blender: Import the original Sketchfab glTF/GLB file into Blender
  2. Select Rigged Meshes: In the Outliner, select all meshes that have skin weights applied (identify these by looking for Vertex Groups in the mesh properties) Screenshot
  3. Clear Parent Relationship: Press Alt + P and choose "Clear and Keep Transformation"
  4. Re-export: Export the file in glTF/GLB format from Blender
  5. Import into Maya: The processed file should now import correctly into Maya

Alternative Sketchfab Workarounds:

  • Disable Complex Features: If you're experiencing issues with rigged or animated Sketchfab assets, you can disable the following options all at once in the import dialog:

  • Import Skin Binding: Disable to import only static geometry without skeleton/deformation data

  • Import Blendshapes: Disable to skip blendshape targets
  • Import Animations: Disable to import only static meshes without animation keyframes

  • This approach imports only the base geometry and materials, allowing you to work with static meshes and avoid potential deformation or animation issues

  • Manual Orientation Correction: Manually adjust object transforms after import

  • Re-rigging: Consider re-rigging complex characters in Maya after import

  • Animation Recreation: For critical animations, recreate keyframes manually in Maya

General Best Practices

  • Test Import: Always test import with a simple version of your asset first

  • Backup Projects: Maintain backups of your Maya scenes before importing complex assets

  • File Validation: Use glTF validators to check file integrity before import

  • Alternative Sources: When possible, obtain assets from sources that use standard glTF exporters

  • Asset Preparation: For complex assets, consider simplifying or optimizing them before import

Round-trip Workflow: Re-exporting Imported Assets

When importing glTF/GLB files and then wanting to export them again using the Babylon exporter, several compatibility issues arise:

Known Export Issues

Material Compatibility Problems:

  1. Shader Type Conflicts: If you selected Standard Surface, Arnold, or OpenPBR when importing files, the Babylon exporter won't process these materials properly

  2. The importer uses aiImage nodes and intermediate conversion nodes

  3. Babylon only accepts normal file nodes without intermediate conversion nodes

  4. Limited Material Support: Babylon doesn't support additional material properties except Clear Coat when using Standard and Arnold shaders. Stingray shader doesn't support glTF extensions. Babylon doesn't have support for OpenPBR

  5. Animation Clip Issues: If imported files have animation clips, the importer adds them to the Time Editor, but Babylon doesn't work with Time Editor

For Basic Material Export:

  • Import Setting: Choose Stingray shader when importing the file to maintain Babylon compatibility
  • This provides basic material properties that Babylon can process correctly

For Assets with Animation Clips: If your asset has animation clips and you need to re-export, follow these steps:

  1. Consolidate Animation Tracks:
  2. Arrange all clips from different tracks into one single track with appropriate time offsets in the time editor window
  3. You can access the Time Editor via Windows > Animation Editors > Time Editor
  4. Select All Related Objects:
  5. In the Outliner, select all node items related to the asset including:
    • Empty transform groups
    • Joints
    • Meshes
    • Any other related nodes
  6. Bake Animation Data:
  7. In the Time Editor's bake dropdown menu, choose "Bake to Scene and Delete" option
  8. This converts Time Editor clips back to standard Maya animation curves
  9. Create Animation Groups:
  10. Using Babylon's Animation Groups UI, create the clips with proper naming
  11. Export the glTF/GLB file using Babylon exporter

Important: This round-trip workflow is primarily intended for basic material properties and simple animations. Complex materials and advanced features may not survive the round-trip process.

Troubleshooting Tips

Asset Source Recommendations

  • Recommended: Use assets from the Khronos Sample Assets repository for testing
  • Reliable: Assets exported from Maya using Babylon exporter or Assets exported from Blender using the built-in glTF 2.0 addon
  • Caution: Sketchfab auto-generated assets may require preprocessing

Export Guidelines

  • Ensure your glTF files follow the official Khronos glTF 2.0 specifications
  • Use standard export tools and avoid custom or experimental exporters
  • Test your exported files with glTF validators before importing to Maya
  • Keep animations simple and prefer transform-based over joint-based animations when possible

Additional Resources