light mix not working

[sbastien_levieux]

Hello,
I have an issue with the light mix... It is not showing during the rendering, do you have an idea what can be the problem?

Thank you!

[fabian_pape]

Hi, you have to go to the render settings under Images > Render Elements > Network you have to add the path of the Render Elements node (/out/renderElements). Also under Export > IPR check Use Render Elements.

That should be it.

[chakarov]

Hello sbastien_levieux , it is working on my side. What is your OS, Houdini version and V-Ray build number? Can you share a simple scene where the problem appears?

[sbastien_levieux]

Hi @chakarov and fabian_pape I forgot to check that: "IPR check Use Render Elements".
Do you have an idea, for the fire motion blur if the vel need to be separate in X,Y,Z or not? If there is any difference, wich solution is the best?

[chakarov]

hi sbastien_levieux , good to hear that lightmix is working. With V-Ray 5 Update2 vector fields are now supported when used as velocity volume. There are no differences if you use one vector volume or separate volumes for X,Y,Z.

[sbastien_levieux]

Hi @chakarov,
This is my Vray build:
V-Ray for Houdini hash:fe945ef from 09 Dec 2021 11:01
V-Ray Core 5.20.02 [58987b7e] from 2 Dec 2021

Do you have any idea how it works for showing motion blur on the flame with the velocity? May be no needed to take care of that? I am looking also for a good setup for flame rendering....

This is what I have for now....


This is an animation of 20 frames: https://i.gyazo.com/11c94dca5340d21a...076a8f1862.mp4

I have also an issue, houdini caches after those 20 frames:



https://drive.google.com/file/d/169U...ew?usp=sharing

Mulitchanel in 1 single exr file is not working for me

[chakarov]

Hi

in order to use motion blur for volumes you just need to provide the velocity field name in V-Ray VolumeGrid Shader > Bindings > Velocity Field.
vel.* - for separate X,Y,Z fields
vel - for vector velocity field

Because every simulation is different from the other I am not sure you will find a setup which will work in any case. You could try to play with Source Remap, Intensity and Color ramps in Fire tab of V-RayVolumeGrid Shader.
something like this:

it will add details to your fire, you could use similar ramp setup to add details to smoke as well

In order to save all channels/elements in a single exr file you need to remove the aov tag from filename. Removing the aov tag will force V-Ray to save all elements in one file if the file format support it.
in your case:
${HIP}/render/${HIPNAME}.01.$F4.exr

I'll send the dump file to our developers, but it will be a lot better if we have your caches and hip file or at least vrscenes for crashing frames. If it is possible you can send them to our support team.

edit:
you could control the strength of motion blur with a multiplier in Rendering tab of V-Ray VolumeGrid Shader

[sbastien_levieux]

Hi chakarov,
Thank you for answering me! I will prepare for you the file and also an email...
The problem seems coming from the sparks.....

Thank you!

[tsvetomira.girginova]

Dear sbastien_levieux, hello.

I have just created a ticket for you (18962) where you could safely upload your files.
Please check your e-mail and send all as described when you are ready.

Waiting for the files.
Thanks in advance.

Best regards,
TS

[sbastien_levieux]

Hi tsvetomira.girginova,
Thanks for your message, the vrayscene exporter is not working, I am sending the hip file and the cache
Do you have new for that error message and the file i sent to you? (vray.dmp)
Best,
Sebastien

[tsvetomira.girginova]

Hi, sbastien_levieux.

Georgy shared the .dmp with our dev team, but the scene will be more helpful for the investigation.
Thank you for sharing it too!

Any news will be posted here.

[sbastien_levieux]

tsvetomira.girginova Thank you so much for you help!