Volumetric and godray tests

Eddy can create some decent godrays with the current feature set, crazy fast to render them too!

Sharing some Game of thrones fan art, created in modo/substance designer. Volumetric rays with Eddy, dust is nuke particles and some Photoshop for dust sprites.

I’ll be making some breakdown videos soon for this project, and sharing the scene.

Great work Matt, I really like the airfizz element. Glad there is some GOT fan art appearing, especially now that we have to wait a year for the final season.


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Would love to see the basic setup for this. Messing around with Eddy today!

Hi there, heres the basic setup for volumetrics,


What i’m doing here is:

  • creating a low density (0.01 or so on mask value) fog volume from a box sdf around the scene.

  • I’m then adding a holdout mesh and a bright point light behind.

  • The shader phase function is set to Henyey Greenstien and settings tweaked for look and backscatter of rays.

Here is a link to the scene and assets https://www.dropbox.com/s/gysgxzff8ldek9y/atmospherics_scene.zip?dl=0

I’m hoping to do a video breakdown of the GOT scene above soon.

NICE! Very interesting.

Hi there,

I have been doing some tests for volumetric atmosphere lit and rendered in Eddy. I came up with some questions maybe you could help me with:

  • At the moment I believe we have point, quad area or environment lights supported in Eddy. Would it be possible to have some kind of distant light, as we do in Mantra/Prman? I found it difficult to adjust the light settings to get nice god-rays at our scene scale:


  • Is/will it possible to import lights from other packages?
  • Any tips on using light fall-off parameters or the shader setting to enhance shadows and reduce noise?
  • I was getting a regular crashes when trying this technique using a volume from camera (e_image), error message:
Eddy[ERROR]   - CUDA driver API error code=702(CUDA_ERROR_LAUNCH_TIMEOUT) the launch timed out and was terminated

Trace/BPT trap

Hi Rob,

  • We don’t currently have a distant light, sorry. I can send off a feature request for you.

  • Can you please give me an idea of roughly what scene scale/size you have there?
    If its really large it may be precision errors stopping the rays from working correctly. A workaround here would be to use axis nodes to scale scene and camera down.

I usually start around this point with the shader.

The fog box i create is usually an SDF box around the scene with an E_mask with a low inside value like 0.01-0.05

  • With the CUDA error, that sounds like we need to have a closer look at your Eddy version, driver version, and OS. If it persists, could you please send all the info you can provide, to support@vortechsfx.com

Hey Matt - thanks for the reply, I will have a play around with the scene scale to see if that improves things.
We work at 0.1 scale in Maya, meaning things will be 10x bigger in nuke: in this case, the bounding cube I have been using for the volume has a cumulative scale of 800x200x200 units.
If you has access to our (MPCs) FTP you can find an example file on there: rnd_fx_Eddy_godRaysTEST_v001.005.nk

I’m still getting the crash after updating to Eddy 1.6 so I will send an email, with the details and above nuke script, to your support email.



Hi Rob,

Yes, a distant/directional light would be useful, we’ll try to get this into an upcoming version.

I don’t think there’s any issue with the scene scale in the example you provided, the shadows seem correct after adjusting the lights a bit.

Most of the noise is coming from the quad area light, which is creating noisy soft shadows since it is quite close to the scene. I changed it to a point light, and also set it to “No falloff” which is a better approximation to the distant light. I increased the intensity to 200 to compensate for these changes. The phase function parameter of 0.99 was a bit extreme, with this setting almost none of the light will be scattered into the camera, unless the camera is looking directly at the light. It’s not really a problem, but does make things harder to tweak. I changed it to 0.8, in general probably 0.9 or 0.95 should be the maximum.

Here’s the result with the light moved a little higher overhead, so that we get shadows cast from the walls of the canyon:

This was using the ‘Low’ template, with minimum/maximum progressions set to 20/100. I also increased the implicit feature size in the shader to 5.0. Since the volume is uniform this is actually safe, and gives a nice performance improvement.

Also I could reproduce the crash you had with the ImageField node, so we’ll debug and fix it.



Hi Niall,

yes, I had found that switching to a point light seemed to help. Thanks for the tips - that tweak to the implicit feature size, really sped up the render times (<25 secs per frame)!


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Hi Rob,

I’ve added something to help get this through, but requires you to adjust your clipping planes more carefully ( specifically the near clipping plane ). The resolvable detail of implicits approaches infinity ( which was causing a timeout ) so setting the near / far boundaries controls the detail you can resolve.

This said the method you are using currently is a lot better anyway and its only really an issue when uses non automatic templates.

the fix will be in the next release.


Hi Rob,

I’ve put the latest dev build up on your client portal page.

Let us know if you have any issues with it.


Great - thanks guys. I will give that a test once we get our license here up and running again :slight_smile:

Hi Rob,

There should be a license extension headed over there very shortly. I’ve also put up a slightly newer dev build on the portal with a few more bug fixes.