How to save rendered 3d bounding box coordinates in the image space (pixel coordinates) from ZED SDK?

[harishkool]

I am following the example shown in zed-examples/object detection/image viewer at master · stereolabs/zed-examples · GitHub. It uses OpenGL to draw objects on the image, by default 3D bounding box coordinates from ZED are normalized. I have tried something similar to the rendering of ‘ID’ on the image for all the 3D bounding box coordinates, like below:

            bbox = objects.object_list[i].bounding_box
        #     _cam_mat = np.array(_cam, np.float32).reshape(4,4)
            N = 8
            hom_obj_coords = np.c_[bbox, np.ones(N)]
            proj3D_cam = np.matmul(hom_obj_coords, _cam_mat) # 8 x 4
            # proj3D_cam[1] = proj3D_cam[1] + 0.25

            # proj2D = [((proj3D_cam[0] / pt4d[3]) * _wnd_size.width) / (2. * proj3D_cam[3]) + (_wnd_size.width * 0.5)
            # , ((proj3D_cam[1] / pt4d[3]) * _wnd_size.height) / (2. * proj3D_cam[3]) + (_wnd_size.height * 0.5)]

            proj2D = [((proj3D_cam[:, 0] / hom_obj_coords[:, 3]) * 1920) / (2. * proj3D_cam[:, 3]) + (1920 * 0.5)
                    , ((proj3D_cam[:, 1] / hom_obj_coords[:, 3]) * 1172) / (2. * proj3D_cam[:, 3]) + ((1172 * 0.5) + ((1172 - 1080)*0.5))]
            proj2D_x = proj2D[0]
            proj2D_y = proj2D[1]

where

_cam_mat

is the projection matrix I got from the OpenGL code. But objects are not getting aligned properly, Is there any way to directly save the rendered 3D bounding box coordinates in the image space i.e., in pixel coordinates ? because OpenGL is doing it anyway but I am not able to understand how to get those final projected pixel coordinates.

[Myzhar]

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Saving rendered 3d bounding box coordinates in the image space (pixel coordinates) from ZED SDK?