Normalizing an imported object

[cs-mshah]

Describe the issue

I am trying to normalize a .glb object using the following code:

def objs_bbox(objs: List[MeshObject]):
    bbox_min = np.array((math.inf,) * 3)
    bbox_max = np.array((-math.inf,) * 3)
    for obj in objs:
        bbox = obj.get_bound_box()
        min_bbox = np.min(bbox, axis=0)
        max_bbox = np.max(bbox, axis=0)
        bbox_min = np.minimum(bbox_min, min_bbox)
        bbox_max = np.maximum(bbox_max, max_bbox)
    return bbox_min, bbox_max


def normalise_objs(objs: List[MeshObject]):
    """Normalise the objects to have a scale of 1 and be centered at the origin.

    :param objs: The objects to normalise
    """
    bbox_min, bbox_max = objs_bbox(objs)
    scale_obj = bbox_max - bbox_min
    scale_factor = 1 / max(scale_obj)
    offset = - (bbox_max + bbox_min) / 2
    root_obj = get_root_obj(objs[0])
    root_obj.set_location(root_obj.get_location() + offset)
    root_obj.set_scale(root_obj.get_scale() * scale_factor)
    
objs = bproc.loader.load_obj(args.object)
normalise_objs(objs)

But the results are weird:

Using both translation and scaling, the final object's location is not correct. Whereas commenting out each one individually gives the correct scale and correct position.

Minimal code example

No response

Files required to run the code

No response

Expected behavior

The object should be scaled and at the correct position being normalized.

BlenderProc version

2.7.0

[cornerfarmer]

Hey,

the bug is in your code. The offset depends on the scaling factor. Multiplying the offset with the scale factor should solve your problem:

 obj.set_location(obj.get_location() + offset * scale_factor)

[cs-mshah]

@cornerfarmer Hey thanks for pointing it out. I had one more question: How should I apply rotation to an object? I tried using the obj.set_rotation on the root node of the gltf object but that didn't seem to work. It is quite confusing. Could you help?