volume_loader configuration file documentation updates

[tbirdso]

Overview

We've received a request for additional documentation and clarity around how configuration files can be formed for the XR Volume Rendering application.

Detailed Summary

HoloHub does not currently offer clear documentation for how to create or update a configuration file for volume rendering. JSON config files are used by both the volume_rendering and volume_rendering_xr applications. Config files are ingested by the volume_loader operator.

It would be good to understand how users can write new files setting:

• camera parameters
• Volume transfer functions
• Lighting
• Other rendering settings

Projects to consider:

• ClaraViz: underlying volume rendering project
• volume_renderer: wraps ClaraViz as a Holoscan operator
• volume_loader: Loads JSON config file
• volume_rendering / volume_rendering_xr applications: Provide custom config files (either in git tracking or data download at build time) for volume rendering

Additional Notes

Related to NVIDIA/clara-viz#47 requesting additional documentation on settings available in the underlying ClaraViz project.