VrayVolumeGrid Fade distance or distance mapping?

[White Wizard]

I'm trying to make voxels' opacity decrease the further from camera they are. I have smoke moving towards the camera and it looks bad to have it pop in from its source in the distance. I want it to fade in as it gets closer.

Do I have any options or am I straight out of luck?

Age based opacity?

[vlado]

Can't you modulate the opacity with a Falloff map in distance fade mode?

Best regards,
Vlado

[White Wizard]

Can't you modulate the opacity with a Falloff map in distance fade mode?

Best regards,
Vlado

I haven't had any luck with that. No matter what I set the distances to, including using a helper object, it's either fully rendered or completely non-existent. Noise textures and others work fine in the texture slot. It seems falloff doesn't work with volumegrids or I'm missing something.

My settings now: Distance blend using camera z-axis and I have my camera positioned so I can peak over a box of smoke to check if it's working. No change in falloff settings at all affects my render though.

EDIT: No luck with VrayDistanceTex either. Similar problem: It either shows up rendered or completely transparent depending on whether the near/far colors are swapped.

[vlado]

Ok. Can you post your setup here or send it to support@chaosgroup.com so that we can take a look?

Best regards,
Vlado

[White Wizard]

I'm able to now see some changes. I don't know what I did but at least Im getting something. However, it's completely unintuitive and finicky adjusting the distance falloff. Still seems incorrect. I'm noticing what seems like an exponential interpretation of distance or opacity when it should be linear? I'm not sure.

volumetric distance fade.zip

[svetlozar.draganov]

You are correct, it works fine when the distance falloff is applied on a single box with the same dimensions but it works strange and exponentially on the VolumeGrid.
We'll log a bug about that behavior into our system and will keep you posted for any updates.