URDF Export Error and Collision Object Error with Left-Handed Rotation Matrix

[1270645409]

Description

version:

• phobos==2.0.0
• blender v3.3 LTS
• scipy==1.13.1

I have created mutiple .obj files in blender, then composite them to a urdf
I encountered two issues when exporting Blender models to URDF using Phobos.

PLEASE NOTE THAT No transformation has been applied to the origin .obj mesh

Issue 1: Rotation Matrix Error

Error Message:

Rot.from_matrix(R).as euler(EULER CONVENTION)
Non-positive determinant (left-handed or null coordinate frame) in rotation matrix 

Also, I meet this error when creating collision object

Context:

• This occurs when exporting a URDF containing multiple objects assembled as links.
• Temporary Fix: Flipping/mirroring the problematic object sometimes resolves the error, but this approach is unreliable.
  

Issue 2: Collision Object Pose Mismatch

Problem:

When creating a collision object (mesh), its pose differs from the original visual object. Specifically, the collision mesh requires an additional 90-degree rotation around the X-axis to align with the visual geometry.
Sometimes, the same problem occurs as the issue 1.

I don't know whether it is normal

Phobos Version

2.0.0

Conditions to reproduce

No response

INI code

Steps to reproduce

• import two obj(body and lid)
• set them to visual
• create link for them
• set the body link to root
• set bone relative for the two link
• select one visual, create collision, then error occurs
• also, when i try to export the whole urdf, the same error occurs

Expected behaviour

for issue 1, I want to export urdf successfully
I want to know why the rotation matrix is left-handed

for issue 2, I want to know why the created collision obj pose is not the same as visual one.

Actual behaviour

for issue 1, when exporting urdf, ERROR: Non-positive determinant (left-handed or null coordinate frame) in rotation matrix
for issue 2, When creating a collision object (mesh), its pose differs from the original visual object. Specifically, the collision mesh requires an additional 90-degree rotation around the X-axis to align with the visual geometry.

Additional context

No response

Checklist

• The issue happens on the latest official version of Phobos and wasn't fixed yet.
• I agree to elaborate the details if requested and provide thorough testing if the bugfix is implemented.
• I added a very descriptive title to this issue.
• I used the GitHub search and read the issue list to find a similar issue and didn't find it.
• I have attached as much information as possible (screenshots, gifs, videos, debug and exception logs, etc).

[Starkku]

You are most likely looking for https://github.com/dfki-ric/phobos, this repository is for a Command & Conquer: Yuri's Revenge engine extension not a Blender addon.

[1270645409]

sorry, i made a mistake