def depth_from_feature_np(feature, k):
    """
    Args:
        feature: numpy array of shape [5, 64, 512], C, H, W,
            the 3th channel is depth channel

    Return:
        depth map, of shape [64, 512]  scaled to  [0 to k],
        for grey scale plotting
    """
    r = feature[3, :, :]
    depth = ((r - r.min()) * (k) / (r.max() - r.min()))
    return depth