Information needed on Python Script, Omnigraphs and Navigation Isaac Example

Omniverse Isaac Sim
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1

Isaac Sim Version

4.2.0

Operating System

Ubuntu 22.04

Topic Description

Detailed Description

I am trying to refer the iw hub navigation example in Isaac Examples to build something of my own. I am relatively new to Omniverse but I have tried to go through as many isaac sim docs as possible. However there are a few things where I am not able to make sense and combine the knowledge of individual tutorials. Here are a few doubts that I have and would appreciate any help possible:

1. IW Hub Navigation Example

I tried the example of iw hub navigation available in the tutorials which I was able to do successfully. However, I was not able to find the python script for this particular example. There isn’t any option that says ‘Open Source Code’ unlike many other Isaac Examples.

Steps to Reproduce

Same as the tutorials.

What I’ve Tried

I tried to search the following location:
.local/share/ov/pkg/isaac-sim-4.2.0/exts/
.local/share/ov/pkg/isaac-sim-4.2.0/standalone_examples/
humble_ws/src/
but had no luck finding it.

I would really appreciate some help understanding how this particular example pipeline is built.
(Finding the answer to: How can I built a complete standalone program to load the scene, objects, robots with lidar, along with the navigation stack and further customize it?)

2. Omnigraphs and Python Script

Question:

  1. Does every Omnigraph that is build using GUI also create a Python Script in the backend, or are the two approaches individual?

3. SDG Pipeline

I have observed that when I make any changes in examples where SDGPipeline Action Graph is available, and then run it, the updates are succesfully run on playing the simulation. But then if I save this update and reopen it in the next isaac sim session, then the the omnigraph under the SDGPipeline doesn’t get saved. However, if I create a new Action Graph and update something and save, then these updates get saved and are usable in the next isaac sim session.

Steps to Reproduce

  1. Open, e.g., rtx_liday.py standalone example. It starts the Isaac Sim application and runs the simulation.
  2. Now, I stop the simulation from the GUI.
  3. Open Action Graph as Window > Visual Scripting > Action Graphs
  4. Add / Remove / Update nodes in the /Render/PostProcess/SDGPipeline Action Graph.
  5. Run the simulation with the update. Sim should run with the updates action Graph.
  6. Now, Save As this project.
  7. Restart a new Isaac Sim session and open the saved file. Try running the simulation or check the action graph. It doesn’t have the updated action graph.

I might be misunderstanding the concepts here. Please help me understand what I am missing.

Questions:

  1. How is the /Render/PostProcess/SDGPipeline Action Graph different from any other custom Action Graphs that can be created?
  2. How can I reflect and save the changes made in SDGPipeline action graph?
  3. Some nodes which are available when updating the SDGPipeline graph are not available when I make a new Action Graph. I tried to build a similar(consider same) graph in a new Action Graph but could not find nodes such as Sd Render Var Ptr. Why is this so?

Any references and links will be helpful regarding these topics. I look forward for a helpful explanation to these topics.

Thanks in Advance!