How to randomly place BOP objects?

[preethamam]

I want objects randomly placed at different locations with the same sampled BOP objects and background texture for different scenes. The below code produces five images with different camera poses, and the objects remain at the exact location.

import blenderproc as bproc
import argparse
import os
import numpy as np

parser = argparse.ArgumentParser()
parser.add_argument('bop_parent_path', nargs='?', help="Path to the bop datasets parent directory")
parser.add_argument('bop_dataset_name', nargs='?', help="Main BOP dataset")
parser.add_argument('cc_textures_path', nargs='?', default="resources/cctextures", help="Path to downloaded cc textures")
parser.add_argument('output_dir', nargs='?', help="Path to where the final files will be saved ")
args = parser.parse_args()

bproc.init()

# load a random sample of bop objects into the scene
sampled_bop_objs = bproc.loader.load_bop_objs(bop_dataset_path = os.path.join(args.bop_parent_path, args.bop_dataset_name),
                                  mm2m = True,
                                  sample_objects = True,
                                  num_of_objs_to_sample = 10)

# load distractor bop objects
distractor_bop_objs = bproc.loader.load_bop_objs(bop_dataset_path = os.path.join(args.bop_parent_path, 'tless'),
                                     model_type = 'cad',
                                     mm2m = True,
                                     sample_objects = True,
                                     num_of_objs_to_sample = 3)
distractor_bop_objs += bproc.loader.load_bop_objs(bop_dataset_path = os.path.join(args.bop_parent_path, 'lm'),
                                      mm2m = True,
                                      sample_objects = True,
                                      num_of_objs_to_sample = 3)

# load BOP datset intrinsics
bproc.loader.load_bop_intrinsics(bop_dataset_path = os.path.join(args.bop_parent_path, args.bop_dataset_name))

# set shading and physics properties and randomize PBR materials
for j, obj in enumerate(sampled_bop_objs + distractor_bop_objs):
    obj.set_shading_mode('auto')

    mat = obj.get_materials()[0]
    if obj.get_cp("bop_dataset_name") in ['itodd', 'tless']:
        grey_col = np.random.uniform(0.3, 0.9)   
        mat.set_principled_shader_value("Base Color", [grey_col, grey_col, grey_col, 1])        
    mat.set_principled_shader_value("Roughness", np.random.uniform(0, 1.0))
    mat.set_principled_shader_value("Specular", np.random.uniform(0, 1.0))

# create room
room_planes = [bproc.object.create_primitive('PLANE', scale=[2, 2, 1]),
               bproc.object.create_primitive('PLANE', scale=[2, 2, 1], location=[0, -2, 2], rotation=[-1.570796, 0, 0]),
               bproc.object.create_primitive('PLANE', scale=[2, 2, 1], location=[0, 2, 2], rotation=[1.570796, 0, 0]),
               bproc.object.create_primitive('PLANE', scale=[2, 2, 1], location=[2, 0, 2], rotation=[0, -1.570796, 0]),
               bproc.object.create_primitive('PLANE', scale=[2, 2, 1], location=[-2, 0, 2], rotation=[0, 1.570796, 0])]

# sample light color and strenght from ceiling
light_plane = bproc.object.create_primitive('PLANE', scale=[3, 3, 1], location=[0, 0, 10])
light_plane.set_name('light_plane')
light_plane_material = bproc.material.create('light_material')
light_plane_material.make_emissive(emission_strength=np.random.uniform(3,6), 
                                   emission_color=np.random.uniform([0.5, 0.5, 0.5, 1.0], [1.0, 1.0, 1.0, 1.0]))    
light_plane.replace_materials(light_plane_material)

# sample point light on shell
light_point = bproc.types.Light()
light_point.set_energy(200)
light_point.set_color(np.random.uniform([0.5, 0.5, 0.5], [1, 1, 1]))
location = bproc.sampler.shell(center = [0, 0, 0], radius_min = 1, radius_max = 1.5,
                        elevation_min = 5, elevation_max = 89, uniform_volume = False)
light_point.set_location(location)

# sample CC Texture and assign to room planes
cc_textures = bproc.loader.load_ccmaterials(args.cc_textures_path)
random_cc_texture = np.random.choice(cc_textures)
for plane in room_planes:
    plane.replace_materials(random_cc_texture)

# Define a function that samples the initial pose of a given object above the ground
def sample_initial_pose(obj: bproc.types.MeshObject):
    obj.set_location(bproc.sampler.upper_region(objects_to_sample_on=room_planes[0:1],
                                                min_height=1, max_height=4, face_sample_range=[0.4, 0.6]))
    obj.set_rotation_euler(np.random.uniform([0, 0, 0], [0, 0, np.pi * 2]))

# Render five different scenes
for _ in range(5):
    # Sample objects on the given surface
    placed_objects = bproc.object.sample_poses_on_surface(objects_to_sample=sampled_bop_objs + distractor_bop_objs,
                                            surface=room_planes[0],
                                            sample_pose_func=sample_initial_pose,
                                            min_distance=0.01,
                                            max_distance=0.2)

    # BVH tree used for camera obstacle checks
    bop_bvh_tree = bproc.object.create_bvh_tree_multi_objects(placed_objects)

    # Sample location
    location = bproc.sampler.shell(center = [0, 0, 0],
                        radius_min = 0.61,
                        radius_max = 1.24,
                        elevation_min = 5,
                        elevation_max = 89,
                        uniform_volume = False)

    # Determine point of interest in scene as the object closest to the mean of a subset of objects
    poi = bproc.object.compute_poi(np.random.choice(placed_objects, size=10))
    # Compute rotation based on vector going from location towards poi
    rotation_matrix = bproc.camera.rotation_from_forward_vec(poi - location, inplane_rot=np.random.uniform(-0.7854, 0.7854))
    # Add homog cam pose based on location an rotation
    cam2world_matrix = bproc.math.build_transformation_mat(location, rotation_matrix)

    # Check that obstacles are at least 0.3 meter away from the camera and make sure the view interesting enough
    if bproc.camera.perform_obstacle_in_view_check(cam2world_matrix, {"min": 0.3}, bop_bvh_tree):
        # Persist camera pose
        bproc.camera.add_camera_pose(cam2world_matrix)

# activate depth rendering
bproc.renderer.enable_depth_output(activate_antialiasing=False)
bproc.renderer.set_max_amount_of_samples(50)

# render the whole pipeline
data = bproc.renderer.render()

# Write data in bop format
bproc.writer.write_bop(os.path.join(args.output_dir, 'bop_data'),
                       dataset = args.bop_dataset_name,
                       depths = data["depth"],
                       colors = data["colors"], 
                       color_file_format = "JPEG",
                       ignore_dist_thres = 10)

[MartinSmeyer]

Just create an outer loop where you alter the scene as described in the BOP challenge examples

[preethamam]

@MartinSmeyer If I use an outer loop, isn't the objects get randomly sampled every time? Also, the background will change for every new scene. What I want is the same background and objects but randomly placed at different locations.

[MartinSmeyer]

Well then just put the part you want to randomize in the loop and everything else outside.