Issues With Importing JSON for RigidTerrain (PyChrono)

[Jack Wagner]

I have been trying to import the example RigidTerrain JSON with the example Wavefront OBJ to examine vehicle behavior on variable landforms and learn more about the wavefront terrain structure, however just trying to implement it into the simulation is causing me issues. I have the following code block to signify the directory for the JSON file:

chrono.SetChronoDataPath('Users/wagne/anaconda3/envs/pychrono/Library/data/vehicle/terrain/')
veh.SetDataPath(chrono.GetChronoDataPath() + 'WaveFrontTest.json')
terrain_file = veh.GetDataPath()

Then simply implement and initialize the terrain with the terrain file:

    terrain = veh.RigidTerrain(hmmwv.GetSystem(), terrain_file)
    terrain.Initialize()

However, every time I try to run this, I receive a fatal access violation and am unsure of what i am doing wrong. I keep thinking it's a simple syntax issue, however everything I try moving around (making terrain_file equal to the exact data path, switching around using Set/GetDataPath, etc.) has been ineffective. 

Assistance would be very helpful. Below is a copy of my terminal's output and the JSON file I am using for reference, although the JSON is nearly identical to the example specified in the PyChrono documentation.

[Jack Wagner]

Additionally, I am using the win-64_pychrono-9.0.0-py39_4852 package downloaded through Anaconda.

[Jack Wagner]

Sorry for spam of replies, but I forgot to include one of the screenshots of my console output, here it the console output in its entirety.

[Radu Serban]

Jack,

 

You misunderstand the meaning of the Chrono and Chrono::Vehicle data paths.  What you are supposed to provide through the functions chrono.SetChronoDataPath and veh.SetDataPath are the locations of *directories* containing data file.  With what you have, the terrain file is probably found fine, but the incorrect setting for the vehicle data path may mess up something else (difficult to tell without seeing your code, but one possibility is if you are using some visualization mesh for the HMMWV vehicle).

 

Try something like this:

chrono.SetChronoDataPath('Users/wagne/anaconda3/envs/pychrono/Library/data/)

veh. SetDataPath(chrono.GetChronoDataPath() + ‘vehicle/')

…

terrain = veh.RigidTerrain(hmmwv.GetSystem(), veh.GetDataFile(‘terrain/WaveFrontTest.json’)

…

 

(Of course, this also assumes that your JSON terrain specification file is correct)

 

--Radu

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[Jack Wagner]

Radu,

Thank you for the response!

After making these changes, I realized that the issue relied with chrono.SetDataPath, as commenting this out immediately removed the access violations albeit without generating any of the mesh terrain. I think the script had a data path already set, however using that method caused some sort of access violation which generated issues in trying to access vehicle information earlier on in the initialization process. 

I think the issue is in my JSON, then? When I loaded the sample RigidHeighMap JSON instead, it was able to run the simulation at ease and with everything loaded correctly, however I think this issue is seperate from what I've been encountering with actually getting the simulation to work.

Thanks again!

-Jack