def transform(self):
        """
        Get the (4, 4) homogenous transformation from the
        world frame to this camera object.

        Returns
        ------------
        transform : (4, 4) float
          Transform from world to camera
        """
        # no scene set
        if self._scene is None:
            # no transform saved locally
            if not hasattr(self, '_transform') or self._transform is None:
                return np.eye(4)
            # transform saved locally
            return self._transform

        # get the transform from the scene
        return self._scene.graph[self.name][0]