Function map_kd_value_to_textures

plib/preprocess_obj.py:153–212

For materials without texture map, this function will create texture map based on Kd. For materials with texture map, this function will multiply the map with Kd value. Args: mtl_filepath: the path to obj material. This function will overwrite mtl and texture maps in the destin

(mtl_filepath: str)

def map_kd_value_to_textures(mtl_filepath: str):
    """
    For materials without texture map, this function will create texture map based on Kd.
    For materials with texture map, this function will multiply the map with Kd value.

    Args:
        mtl_filepath: the path to obj material. This function will overwrite mtl and texture maps in the destination

    Returns:
    """
    with open(mtl_filepath, 'r+') as f:
        mtl_dir, _ = os.path.split(mtl_filepath)
        mtl_content = f.read().split('newmtl')
        f.seek(0)
        new_texture_id = 0
        for material in mtl_content:
            material_lines = material.splitlines()
            Kd_line_ids = [i for i, x in enumerate(material_lines) if x.lstrip().startswith('Kd')]
            texture_lines = [x for x in material_lines if x.lstrip().startswith('map_Kd')]
            if Kd_line_ids:  # Kd_line is not empty, assume it is a valid material
                material_lines[0] = 'newmtl' + material_lines[0]  # add delimiter back
                Kd_line = material_lines[Kd_line_ids[0]]
                Kd_values = np.asarray(Kd_line.split()[1:], dtype='f4')  # parse three Kd values

                texture_line = None
                if texture_lines:
                    texture_line = texture_lines[0].lstrip()  # ignore spaces begin
                    texture_line = texture_line[6:].replace(" ", "")  # remove map_Kd and space
                    # some files may be missing, check first
                    if not os.path.exists(os.path.join(mtl_dir, texture_line)):
                        # remove the map line
                        material_lines.remove(texture_lines[0])
                        texture_line = None

                if texture_line is None:
                    Kd_values = (Kd_values * 255).astype(np.uint8)
                    Kd_img = np.tile(np.reshape(Kd_values, [1, 1, 3]), (100, 100, 1))
                    #  for some reason, open3d would make texture boundary darker
                    #  thus, use small textures (1x1 image) would make texture color non-uniform
                    #  use 100x100 is more robust
                    Kd_img = Image.fromarray(Kd_img)  # reshape to a 1x1 image
                    new_texture_path = f"new_textures/{new_texture_id}.png"
                    new_texture_dir = os.path.join(mtl_dir, 'new_textures')
                    if not os.path.exists(new_texture_dir):
                        os.makedirs(new_texture_dir)
                    Kd_img.save(os.path.join(mtl_dir, new_texture_path))
                    material_lines[-1] = f"map_Kd ./{new_texture_path}"  # replace last empty line by map_Kd
                    material_lines.append("")
                    new_texture_id += 1
                else:
                    with Image.open(os.path.join(mtl_dir, texture_line)) as Kd_img:
                        Kd_img_array = mesh_utils.clean_texture(np.asarray(Kd_img))
                        Kd_img_array = Kd_img_array * Kd_values
                        Kd_img = Image.fromarray(Kd_img_array.astype(np.uint8))
                        Kd_img.save(os.path.join(mtl_dir, texture_line))
                material_lines[Kd_line_ids[0]] = 'Kd 1 1 1'  # no need for Kd values anymore

            for x in material_lines: