RTX Lidar shows a transparent object in the Rviz visualization

[user10687]

I was trying out the following tutorial on using the RTX Lidar.
I changed the material for one of the objects to OmniGlass and expected that it would be transparent to the Lidar beam and hence would not show up in the visualization. However, the object still appeared in the Rviz visualization. I also tried the ClearGlass material but the same happened.

Could you please help me with this. Thanks!

[rthaker]

Hi @user10687 - Someone from our team will review and answer your question.

[mcarlson1]

The RTX Lidar does not use the same material system as the rest of rendering. So it will not see OmniGlass objects as transparent. The list of sensor materials, and how to use them is listed here:

https://docs.omniverse.nvidia.com/app_isaacsim/app_isaacsim/isaac_sim_sensors_rtx_sensor_materials.html

[user10687]

Thank you @mcarlson1 for your recommendation. I read through the documentation you had referenced and it made sense to me. I implemented them by changing the respective files and again collected a bag file. Upon visualizing the output, the issue however still persists.

I am attaching screenshots of Isaac Sim GUI which shows Stage as well as the changes the documentation suggests making. Could you please help me with what I might be doing wrong here ?

[martini_rosa]

Hi! I’m trying to test the same feature with the RTX LiDAR but didn’t get the material on my mesh. I did set the “RtxSensorMaterialMap.csv” with an “water_test_01,WaterStandard” example but it doesn’t show in the material dropdown, can you help me?

Also, for the devs, there is some example video of this sensor material + rtx lidar feature? It may be more clear to follow. Thanks!

[user10687]

Hi @martini_rosa . I have not yet been able to resolve this issue. If you can raise a new request (also link this post in there) that might help bring it to the notice of the moderators.

[martini_rosa]

@mcarlson1

is listed here:

Hi @mcarlson1, could you help with this part of the sensor material tutorial? It’s not clear how to add the sensor material to a primitive. I should write the same name as the .csv file or it should show the material in the dropdown of the “Material on selected models”?

[mcarlson1]

Hi @martini_rosa . The entry “water_test_01,WaterStandard” is not correct. But it’s easy to correct it! It looks like in the screen grab above that the material assigned to the cube is:
/World/test_rtx1/Looks/cube_1
so cube_1 is your first entry, because it is the first name after the /Looks/

The rtx.materialDb.rtSensorNameToIdMap setting in the extension.toml should not be changed. But it can be used to see what material names to use. So if you want a Water sensor material to be assigned to Cube (which has the /World/test_rtx/Looks/cube_1 material assigned to it), your entry would be:

cube_1,WaterStandardMaterial

Good luck,
Mark

[mcarlson1]

Note: The sensor_material system is not tied to the UI in any way, so you will not see it there. This will change in later releases, and you will be able to set sensor materials directly on the Looks materials without the use of the csv file.

[martini_rosa]

@mcarlson1

, becau

Thank you for the fast reply @mcarlson1! The above screen grab was from the user @user10687, i didn’t understand how to add the sensor material to my /Looks/ option. I have set this scene with the rtx lidar and edited the .toml and .csv file:

Which step is missing to add the sensor material to “cube_1” example? How to map the “cube_1” material from the .csv to the mesh “cube_1”, thats the point.

[mcarlson1]

The Looks are materials. You have to add a material to your object, and then whatever name in the material is after the /Looks/ section in the prim name of the material is what is used by the RTX lidar to match in the csv file.

For example, If you create a cube, and then right click on the cube and Create->Material->OmniGlass you will then get this in the property manager when selecting the cube:

You can see in the Materials on selected models section that /World/Looks/OmniGlass is the material assigned to the cube. So if you want that cube to be glass to the lidar, you would add the following line to the .csv file:

OmniGlass,GlassStandardMaterial

[mcarlson1]

Note that you may have to have multiple returns. One of those returns will be weak, the one from the glass, and the other will be strong, the one from past the glass… I am not sure which one the debug point cloud render node would pick up. Probably both.

[mcarlson1]

This forum post has some nice results for transparent objects, and may help.