使用pyrender渲染对象的视图

Question

我想从不同角度创建一个物体（.obj 文件）的 12 个图像。这个想法是使用 Pyrender 从对象的前面渲染一个视图，然后围绕对象旋转相机 12 步，并每次渲染另一个视图。

大多数渲染图像的问题是，图像中的部分对象被切断。

我尝试更改正交相机的参数（xmag、ymag、znear、zfar），但没有成功。我还尝试使用透视相机，它解决了同样的问题。改变灯光/相机位置也不起作用。

图像_示例：

def render_views(in_path, out_path):
    
    def create_rotation_matrix(cam_pose, center, axis, angle):
        # Step 1: Translate camera pose to the origin
        translation_matrix = np.eye(4)
        translation_matrix[:3, 3] = -center
        
        translated_cam_pose = np.dot(translation_matrix, cam_pose)

        # Step 2: Create rotation matrix
        rotation_matrix = rotation_matrix_from_axis_angle(axis, angle)

        # Step 3: Combine translated camera pose and rotation matrix
        final_cam_pose = np.dot(rotation_matrix, translated_cam_pose)

        return final_cam_pose

    def rotation_matrix_from_axis_angle(axis, angle):
        # Normalize the axis
        axis = axis / np.linalg.norm(axis)
        
        # Calculate components of the rotation matrix
        c = np.cos(angle)
        s = np.sin(angle)
        t = 1 - c
        x, y, z = axis

        # Build the rotation matrix
        rotation_matrix = np.array([
            [t*x*x + c,   t*x*y - z*s, t*x*z + y*s, 0],
            [t*x*y + z*s, t*y*y + c,   t*y*z - x*s, 0],
            [t*x*z - y*s, t*y*z + x*s, t*z*z + c,   0],
            [0,           0,           0,           1]
        ])

        return rotation_matrix

    ### number of views to create
    increment = 12

    ### factor to set light distance to object -> multiplied with largest dimension later
    light_distance_factor = 1
    ### dimension factor, camera distance to object -> multiplied with largest dimension later
    dim_factor = 1 

    ### load obj_file and create mesh
    mesh = trimesh.load(in_path)
    mesh = pyrender.Mesh.from_trimesh(mesh)

    ### create light
    # light = pyrender.PointLight(color=[1.0, 1.0, 1.0], intensity=2.0)

    ### create scene and add mesh of object
    scene = pyrender.Scene()
    scene.add(mesh)

    ### Find the largest dimension of the object to set camera and light distance accordingly
    ### Supposed to represent the distance of the two points furthest apart from each other
    larg_dim = np.max(mesh.bounds[1]-mesh.bounds[0])
    print('###\n ', larg_dim, '\n###')

    ### set camera distance 
    cam_dist = dim_factor * larg_dim
    # print('###\n ', cam_dist, '\n###')

    ### set lights distance
    light_distance = light_distance_factor * larg_dim
    # if lights distance is under 5 it resolves in overlightening
    if light_distance <= 5:
        light_distance = 5

    ### create lights around the object and add to scene
    for direction in ['front', 'back', 'left', 'right', 'top', 'bottom']:
        light_pose = np.eye(4)
        print(light_pose)
        if direction == 'front':
            light_pose[2, 3] = light_distance
        elif direction == 'back':
            light_pose[2, 3] = -light_distance
        elif direction == 'left':
            light_pose[0, 3] = -light_distance
        elif direction == 'right':
            light_pose[0, 3] = light_distance
        elif direction == 'top':
            light_pose[1, 3] = light_distance
        elif direction == 'bottom':
            light_pose[1, 3] = -light_distance
        
        light = pyrender.PointLight(color=[1.0, 1.0, 1.0], intensity=50.0)
        scene.add(light, pose=light_pose)

    ### set orthographic camera and add to scene
    def_pose = np.eye(4)
    camera = pyrender.OrthographicCamera(xmag=cam_dist, ymag=cam_dist, znear=0.05, zfar=3*larg_dim)
    cam_node = scene.add(camera, pose=def_pose)

    ### create renderer
    ren = pyrender.OffscreenRenderer(800, 800)
    
    ### create views
    center_point = np.array([0, 0, 0])
    axis_base = [0,1,0]
    for inc in range(1,increment+1):
        ### get current camera-pose, rotate around axis, set new pose to scene           
        cam_pose =  scene.get_pose(cam_node)
        rot_axis = np.array(axis_base)
        rot_angle = np.pi / increment
        cam_pose = create_rotation_matrix(cam_pose, center_point, rot_axis, rot_angle)
        scene.set_pose(cam_node, cam_pose)
        ### render scene
        color, _ = ren.render(scene)
        ### save image
        im = Image.fromarray(color)
        im.save(os.path.join(out_path, 'renview' + '['+ str(inc) +'].png')) 

render_views(src_path, dst_path)

Answer 1

使用下面的函数来生成新的姿势。如果您愿意，可以随机更改它。

def random_camera_pose(radius=2.0):
theta = np.random.uniform(0, 2* np.pi)  # theta is the angle with the z-axis

rot_z = np.array([
    [np.cos(theta), -np.sin(theta), 0, 0],
    [np.sin(theta),  np.cos(theta), 0, 0],
    [0,              0,             1, 0],
    [0,              0,             0, 1]
])

pose = np.array([
    [0.0,  -np.sqrt(2)/2, np.sqrt(2)/2, 0.5],
    [1.0, 0.0,           0.0,           0.0],
    [0.0,  np.sqrt(2)/2,  np.sqrt(2)/2, 0.5],
    [0.0,  0.0,           0.0,          1.0]
])

cam_pose_rotated = np.dot(rot_z, pose)
print(cam_pose_rotated)

return cam_pose_rotated

在所有scene.add()中使用上面获得的相机位姿作为相机节点

ren = pyrender.OffscreenRenderer(800, 800)

# Render the scene from each random camera pose - 12 views
for i in range(12):
    # Create a camera
    camera = pyrender.PerspectiveCamera(yfov=np.pi / 3.0)

    # Generate a random camera pose
    camera_pose = random_camera_pose()

    # Add the mesh obj to the scene
    mesh_node = scene.add(mesh, pose=drill_pose)

    # Add the camera to the scene with the specified pose
    camera_node = scene.add(camera, pose=camera_pose)

    # Render the scene
    color, depth = renderer.render(scene)


    im = Image.fromarray(color)
    im.save(os.path.join(out_path, 'renview' + '['+ str(inc) +'].png'))

    # Remove the camera from the scene
    scene.remove_node(camera_node)