def _pixel_to_clip()

in pytouch/tasks/surface3d/geometry.py [0:0]

• 16 lines of code
• 1 McCabe index (conditional complexity)

def _pixel_to_clip(pix_pos, depth_map, params):
    """
    :param pix_pos: position in pixel space, (2, N)
    :param depth_map: depth map, (H, W)
    :return: clip_pos position in clip space, (4, N)
    """
    x_pix = pix_pos[0, :]
    y_pix = pix_pos[1, :]

    H, W = depth_map.shape
    f = params.z_far
    n = params.z_near

    # pixel -> ndc coords
    x_ndc = 2 / (W - 1) * x_pix - 1  # [0, W-1] -> [-1, 1]
    y_ndc = 2 / (H - 1) * y_pix - 1  # [0, H-1] -> [-1, 1]
    z_buf = depth_map[y_pix, x_pix]

    # ndc -> clip coords
    z_eye = -z_buf
    w_c = -z_eye
    x_c = x_ndc * w_c
    y_c = y_ndc * w_c
    z_c = -(f + n) / (f - n) * z_eye - 2 * f * n / (f - n) * 1.0

    clip_pos = torch.stack([x_c, y_c, z_c, w_c], dim=0)
    return clip_pos