What is neighbours_distance ?

[BedirhanKeskin]

Hello,
What is the neighbours_distance and difference with the distance definition inside Lidar?
They are inside MULTI_AGENT_METADRIVE_DEFAULT_CONFIG
I guess the unit is in meters?
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[pengzhenghao]

Hi @BedirhanKeskin ,

neighbours_distance is nothing to do with Lidar and it is in fact not used at all in native MetaDrive!

It is used in other work, namely one of our previous paper and it is nothing to do with Lidar. Maybe we should remove it to avoid confusion.

Thanks!

[pengzhenghao]

Oh though we should probably not discuss it here, I remember you are working on Multi-agent MetaDrive and please make sure to pull latest MetaDrive. This is because we recently identify a bug that might hurt multi-agent training. See #161 for details. Thanks!

[BedirhanKeskin]

Thank you!!
Then the distance argument parameter inside the lidar dictionary affects other_v_info data acquired from lidarObserver, doesn't it?
Also, What does the 40 mean there exactly?

Best Regards,

[pengzhenghao]

Then the distance argument parameter inside the lidar dictionary affects other_v_info data acquired from lidarObserver, doesn't it?

That's correct.

Also, What does the 40 mean there exactly?

The Lidar module will send (by default) 240 lasers, all centered at current ego vehicle's center. Each this laser has 40 meters length at most if it does not shot any object. Otherwise the laser has the length = distance to nearest obstacle.

The Lidar module will return a 240-dim vector, rescaled to [0, 1] but has the physical range [0, 40m], representing the shortest distance to the obstacle at the corresponding direction at each angle.

Note that in MARL env, the number of lasers is 70.

[BedirhanKeskin]

Thanks for the great explanation!!