如何从深度图像和边界框创建 OrientedBoundingBox

Question

我想使用分段掩模（矩形）和深度图像裁剪点云（我可以认为现在没有旋转）。

import open3d as o3d

## dummy pointcloud
demo_icp_pcds = o3d.data.DemoICPPointClouds()
pcd = o3d.io.read_point_cloud(demo_icp_pcds.paths[0])

## dummy depth mask
depth_mask = np.ones((640, 480), dtype=np.uint8)

## Crop PCD

## mask boundaries: [(xmin, xmax), (y_min, y_max)]
rect = [(20, 50), (70, 75)]

o_box = o3d.geometry.OrientedBoundingBox()
o_box.center = [0.0, 0.0, 0.0]
o_box.extent = [1.0, 2.0, 3.0]
o_box.R = [[1, 0, 0], [0, 1, 0], [0, 0, 1]]

cropped_pcd = pcd.crop(o_box)

我想将矩形 (x, y) 和深度 z 的信息提供给定向边界框。有人能告诉我该怎么做吗？谢谢。

Answer 1

这是我的解决方案供参考：

def obbs_from_depth_mask(
    depth: np.ndarray, rects: List[List]
) -> List[o3d.geometry.OrientedBoundingBox]:
    obbs = []
    for rect in rects:
        obb = o3d.geometry.OrientedBoundingBox()
        ## [xmin, xmax, ymin, ymax]
        x_min = rect[0]
        y_min = rect[2]
        z_min = depth[y_min, x_min]
        ##
        x_max = rect[1]
        y_max = rect[3]
        z_max = depth[y_max, x_max]

        center = [
            (x_min + x_max) / 2,
            (y_min, y_max) / 2,
            (z_min + z_max) / 2,
        ]
        half_extent = [
            math.abs(x_max - x_min) / 2,
            math.abs(y_max - y_min) / 2,
            math.abs(z_max - z_min) / 2,
        ]
        scaling_matrix = np.array([
            [half_extent[0], 0.0, 0.0],
            [0.0, half_extent[1], 0.0],
            [0.0, 0.0, half_extent[2]]
        ])
        translation_matrix = np.array([
            [1.0, 0.0, 0.0, -center[0]],
            [0.0, 1.0, 0.0, -center[1]],
            [0.0, 0.0, 1.0, -center[2]],
            [0.0, 0.0, 0.0, 1.0       ]
        ])
        rotation_matrix = translation_matrix * scaling_matrix
        obb.center = center
        obb.extent = half_extent
        obb.R = rotation_matrix
        obbs.append(obb)

    return obbs