Issues with ScenarioEnv Navigation Info

[chrisgao99]

Hello,

I'm trying to understand the ScenarioEnv navigation info, which is the 22 dimension array in obs["state"][19:41]. I read the metadrive/metadrive/component/navigation_module/trajectory_navigation.py and according to the implementation, navi_info should contain :

• The relative positions of up to 10 navigation waypoints in the ego vehicle’s local coordinate system, one heading direction,one rhs direction (each with 2 dimensions).
• The lateral position of the vehicle relative to the reference trajectory (1 dimension).
• The heading difference between the vehicle and the trajectory (1 dimension).

However, I noticed two issues while printing navi_info at every env step:

1. The last two dimensions (lateral position and heading error) are always 0.
2. Each odd-even pair of navi_info dimensions are identical.

An example output of the 22 dim could be like this:
navi info: [0.5557164 0.5557164 0.5890485 0.5890485 0.6223807 0.6223807 0.6557128 0.6557128 0.68904495 0.68904495 0.7223771 0.7223771 0.7557093 0.7557093 0.7890414 0.7890414 0.82237357 0.82237357 0.50001776 0.5000794 0. 0. ]
Like the example

• ckpt position in heading and rhs are always the same, is this normal?
• when the road is a curve, no matter in which direction it goes, the heading and rhs value are always bigger than 0.5, so how can I tell the car should go left or right?
• the last two dimensions are always zero, including pg map, nuscenes map, so why are we keeping the two dimension? and I think we already have heading difference and lateral in ego car info obs["state"][0:19]