Encountering an error when loading texture.

[keiohta]

I'm trying to load a YCB object but I have encountered an error when loading a texture (so this question might be relevant to this discussion). I'm not sure how I can inform you correctly, so I put the encountered error, the script I used, and full scripts and data so you can reproduce it on your side.

The error

The error occurred when rendering the simulator.

$ python scripts/example_load_urdf_sapien.py 
[2022-11-11 14:02:01.575] [svulkan2] [warning] requested: 0, 0; available 1024-1024, 768-768
Traceback (most recent call last):
  File "/homes/ota/workspace/robotics/mask_rcnn_ycb/scripts/example_load_urdf_sapien.py", line 71, in <module>
    main()
  File "/homes/ota/workspace/robotics/mask_rcnn_ycb/scripts/example_load_urdf_sapien.py", line 67, in main
    render(scene, renderer, camera)
  File "/homes/ota/workspace/robotics/mask_rcnn_ycb/scripts/example_load_urdf_sapien.py", line 51, in render
    viewer.render()
  File "/homes/ota/anaconda3/envs/mask_rcnn/lib/python3.7/site-packages/sapien/utils/viewer.py", line 1849, in render
    self.info_window,
RuntimeError: filesystem error: cannot make canonical path: No such file or directory [/homes/ota/workspace/robotics/mask_rcnn_ycb/data/ycb/077_rubiks_cube/google_16k/texture_map.png ]

An weird point is that the file does exist as:

 ls -la /homes/ota/workspace/robotics/mask_rcnn_ycb/data/ycb/077_rubiks_cube/google_16k/texture_map.png
-rw-r--r-- 1 ota merl 4102208 Nov 20  2015 /homes/ota/workspace/robotics/mask_rcnn_ycb/data/ycb/077_rubiks_cube/google_16k/texture_map.png

Also, I can load the object via the same URDF using pybullet as:

I'll put the pybullet code I used below.

The SAPIEN Code I used

The full code, named "scripts/example_load_urdf_sapien.py", is as follows:

import os

import numpy as np
from transforms3d.euler import mat2euler
import sapien.core as sapien
from sapien.utils.viewer import Viewer


def init_cam(scene, cam_pos, width=640, height=480, fovx=35, fovy=35):
    near, far = 0.1, 100
    camera_mount_actor = scene.create_actor_builder().build_kinematic()
    camera = scene.add_mounted_camera(
        name="camera",
        actor=camera_mount_actor,
        pose=sapien.Pose(),  # relative to the mounted actor
        width=width,
        height=height,
        fovx=np.deg2rad(fovx),
        fovy=np.deg2rad(fovy),
        near=near,
        far=far)

    # Compute the camera pose by specifying forward(x), left(y) and up(z)
    cam_pos = np.array(cam_pos)
    forward = -cam_pos / np.linalg.norm(cam_pos)
    left = np.cross([0, 0, 1], forward)
    left = left / np.linalg.norm(left)
    up = np.cross(forward, left)
    mat44 = np.eye(4)
    mat44[:3, :3] = np.stack([forward, left, up], axis=1)
    mat44[:3, 3] = cam_pos
    camera_mount_actor.set_pose(sapien.Pose.from_transformation_matrix(mat44))

    scene.step()  # make everything set
    scene.update_render()
    return camera, camera_mount_actor


def render(scene, renderer, camera):
    viewer = Viewer(renderer)
    viewer.set_scene(scene)
    model_matrix = camera.get_model_matrix()
    model_matrix = model_matrix[:, [2, 0, 1, 3]] * np.array([-1, -1, 1, 1])
    rpy = mat2euler(model_matrix[:3, :3]) * np.array([1, -1, -1])
    viewer.set_camera_xyz(*model_matrix[0:3, 3])
    viewer.set_camera_rpy(*rpy)
    viewer.window.set_camera_parameters(near=0.05, far=100, fovy=1)
    while not viewer.closed:
        scene.step()
        scene.update_render()
        viewer.render()
    viewer.close()


def main():
    engine = sapien.Engine()
    engine.set_log_level("error")
    renderer = sapien.VulkanRenderer()
    engine.set_renderer(renderer)

    scene = engine.create_scene(sapien.SceneConfig())
    loader = scene.create_urdf_loader()
    urdf_path = os.path.join("data", "ycb", "002_master_chef_can.urdf")
    loader.load(urdf_path)

    camera, _ = init_cam(scene, cam_pos=np.array([-2, 0, 0]))
    render(scene, renderer, camera)


if __name__ == "__main__":
    main()

The PyBullet Code I used

import os

import pybullet as p
import pybullet_data


def main():
    p.connect(p.GUI)  # or p.DIRECT for non-graphical version
    p.setAdditionalSearchPath(pybullet_data.getDataPath())  # used by loadURDF
    p.setGravity(0, 0, -10)
    p.loadURDF("plane.urdf")

    init_pos = [0, 0, 2]
    init_orn = p.getQuaternionFromEuler([0, 0, 0])

    # load model
    urdf_path = os.path.join("data", "ycb", "002_master_chef_can.urdf")
    p.loadURDF(urdf_path, init_pos, init_orn)

    while True:
        p.stepSimulation()
    p.disconnect()


if __name__ == "__main__":
    main()

Structure of the attached scripts and data to reproduce the results

I attached the minimal codes and data to reproduce the error.
discussion_load_error.zip

$ tree
.
├── data
│   └── ycb
│       ├── 002_master_chef_can
│       │   └── google_16k
│       │       ├── kinbody.xml
│       │       ├── nontextured.ply
│       │       ├── nontextured.stl
│       │       ├── texture_map.png
│       │       ├── textured.dae
│       │       ├── textured.mtl
│       │       ├── textured.obj
│       │       ├── textured_vhacd.obj
│       │       └── textured_vhacd.obj.convex.stl
│       └── 002_master_chef_can.urdf
├── environment.yml
└── scripts
    ├── example_load_urdf_bullet.py
    └── example_load_urdf_sapien.py

[fbxiang]

This is caused by an extra whitespace in the textured.mtl file. Note there is a whitespace in the error message.
[/homes/ota/workspace/robotics/mask_rcnn_ycb/data/ycb/077_rubiks_cube/google_16k/texture_map.png ]
You can remove it as a temporary workaround. I'll see if I can fix it in the next release.

[keiohta]

Hi @fbxiang , sorry for the late reply. Thanks for clarifying that the problem is on my side, and sharing the workaround! I'll be careful about the filenames. Thanks!