I am trying to work out how to do various cinematic effects in Omniverse. This post is one step on that journey, particularly for “God Rays” (sunbeams) through the clouds.
Here is an extreme example (generated by DALL-E) of the sort of effect I am after.
The challenge I have had is to get the levels of contrast as in the above image. Using the path tracing renderer with “volumetric fog” turned on and adjusting the “density” setting I managed to get the following. You can see the beams of light shining through the window and onto the floor.
But instead of just the beams of sunlight, the whole room looks foggy. Maybe the shot background needs to be darker to help the beams of light stand out. The first image above had dark ground, dark hills, and dark thunder clouds.
There are some teasers around of what may be possible. For example:
One of the demo scenes is called “DaVinci’s Workshop”. It is going to be released as a demo project… “soon”. It has a few shots with clearer sunbeams.
Update 2023-12-07: There was a video that talked a bit more about the above (and they confirmed they just used fog).
Another image from the Omniverse start up splash sequence.
Sheng-Chi from the Omniverse Discord server has been experimenting too. If you look where the sun is, you can see some beams of light around the sun, although this is more of a bloom effect. That is, it shows a flare-out from a strong light source, rather than a sunbeam (showing dust/moisture in the air).
Zooming in you can see the effect a bit clearer.
Another shot he rendered using IRay.
Zooming in again, rays of light can be seen. Again, dark clouds.
Peka previously reported some success on the Omniverse forums.
Using “Global Volumetric Fog” with Path Tracing (ray tracing does not work much) with a Anisotropy Factor (g) of 0.87 I managed to get the following image. This is better – the boxes near the top of the shot are clearer.
The settings I used are:
But my goal is for beautiful scenery shots, like a sunrise in a forest with fog. Again, an AI generated shot, but illustrates the importance of an overexposed sun and dark underexposed trees.
Next steps? Study photography more! It appears that extreme dynamic range (very bright and very dark colors) helps, so it may be a matter of fog plus post processing effects such as bloom and color correction to accentuate the strength of sunbeams when they do appear.
Additional photography reading:
- https://www.ellenborggreve.com/blog/2018/8/how-to-capture-magical-sun-rays
- https://visualwilderness.com/fieldwork/landscape-photography-tips-for-capturing-dramatic-sunbeams
Update: 2023-12-07: VDB files may be another way to do fog, to get more texture than the Omniverse built in fog. There are some free VDB files from JangaFX that can be used with Omniverse.
Extra Ordinary, the Series 