I started fiddling with Blender source code, since I need the .dae export to have vectors for bone transformations instead of matrices. I managed to change the bone node data as it was just a matter of removing an if-branch in TransformWriter. However, the animations still use matrices and AnimationExporter has multiple bone animation -related functions. Any tips on where I should start looking for a solution in order to replace the matrices with vectors?

What set of vectors were you planning to replace the matrix with? A separate vector encoding the translation and rotation?

Yeah, a bit like they are used in node transformations when TransRotLoc option is selected. Although, I started wondering about the need of converting the skin’s matrices, since they are not directly related to transforms (if I’ve understood the Collada specification correctly).

Each PoseBone has a field ‘location’ and ‘rotation_quaternion’ or ‘rotation_euler’ that tells how the bone is positioned. These values ultimately feed into the final ‘matrix’ parameter.