Scene graph tool does not work with multiple robots

[yubinwang11]

It seems that the function of _scene_graph_builder.start(self.scene) in OmniGibson/omnigibson/scene_graphs/graph_builder.py only supports single agent settings:

if self._robot_name is None: assert ( len(scene.robots) == 1 ), "Cannot build scene graph without specifying robot name if there are multiple robots." self._robot = scene.robots[0] else: self._robot = scene.object_registry("name", self._robot_name) assert self._robot, f"Robot with name {self._robot_name} not found in scene." The self._robot_name should be a list instead of a string when multi-agent is considered.

Thanks a lot for your review.

[cgokmen]

Thanks for the report. We will fix this for our next release.

[hang-yin]

Here's a proposed fix: https://github.com/StanfordVL/OmniGibson/pull/836