Dome light resolution and HDRI

[FlynnAD]

Is there any relationship between the dome light's resolution (visible in the Modifier rollout) and the HDRI resolution as far as rendering quality goes?
The vray help doc only noted the dome light resolution generically (for all lights) as: "Res ? Specifies the resolution at which the texture is resampled for importance sampling."

Is there any real minimum, or perhaps industry rules-of-thumb for HDRI resolution? I've seen HDRI's advertised up to 20,000 pixels. Are these used more for animation backgrounds at 4K rather than for the need for super-detailed HDRI lighting?

I tried a small 500 pixel HDRI for speed. It seemed that the HDRI was so small, and the sun so tiny and pixelated itself, that the resulting sunlight shadows were doubled, rather than having a soft falloff. It seemed like the sun light was coming from two pixels only. Increasing the resolution of the HDRI to 5000 pixels gave much better results, but is this overkill? Does the best HDRI resolution depend upon your desired rendering resolution?

A prior forum post noted that the minimum dome light resolution was automatically internally increased to 2048 now, even if your scene's light notes 512 resolution, here: https://forums.chaosgroup.com/forum/...ution-vray-3-3

Thanks for clarifying,
Matt

[kosso_olli]

There is no need to touch this parameter at all. In my eyes, it should be hidden to the user.

[Deflaminis]

It used to be that you'd get really aliased reflections if you left this on 512 or whatever the default is. Is that no longer true? I was under the impression it controls the resolution of reflections of the HDRI. My info is a couple years old, may have been updated.

[joconnell]

It was a resolution that the map used for diffuse / GI light was downsampled to, the full res was used for reflections.

[Deflaminis]

I thought I remembered a thread with a car window and blocky reflections, but I guess I was wrong. I did find this thread which suggested it's a material setting. https://forums.chaosgroup.com/forum/...ction-in-glass

Thanks for the info.

[joconnell]

Yeah you're right! There used to be that issue there was a maxscript command that you'd run on the domelight to make it use the original res for reflections but downsample for lighting to get cleaner results!

[kosso_olli]

This was many years ago. You don't need to do that anymore. Just use the full res HDRI in the domelight, and V-Ray will take care of anything else.

[joconnell]

Ah the good old days, when men were men and samples were samples...

[Deflaminis]

Haha! Well played.

[kosso_olli]

I always get angry when I see so much wrong information. Take a look at all the videos regarding V-Ray over at Youtube. Even most of the recent videos posted some months ago by various people still suggest using IR+LC and ambient occlusion. That stuff was important ten years ago, but these days none of this is neccessary. And they get tens of thousands of views.

Edit: That was my 1000th post. And it is a rant, great...

[anthonyh]

If IR is the `wrong` way then shouldn`t you blame vray for still having it ? After all they`ve had 10 years to remove it apparently. `9)
(don`t change my wink text for an emoji.. grrr)

[Wilyman]

If the general consensus is that the domelight resolution no longer does anything, then I'm assuming the problem I'm having must be a bug.
But I'm finding that when I use reflective materials with a glossiness value just below one, I'm getting very blocky reflections when the res is set at its default 2048.
At 8192, it's much smoother, and I assume it would be better still with a higher number as the HDRIs are 14000 pixels wide.
At glossiness = 1, they're pin sharp regardless of resolution.

Sorry the example isn't overly clear. It's a confidential scene, so I had to crop a part that showed the problem without showing too much else!
2048 on the left, 8192 on the right...

Weirdly, I don't remember seeing this problem before this week, and I've been on 3.60.03 since it came out, so nothing's changed there.

Any solutions would be great, or even just a method of setting the dome res to 14140 so it matches the sphere, as I can't do it in the settings.

Cheers,

John

[kosso_olli]

There was on old line that you typed into the listener with the domelight selected: $.dome_visibleOriginal=2
This sets the resolution to the one of the HDRI, even if the GUI says something different.
However, I haven't seen the issue you are describing in years. I imagine your HDRI's are about as big as ours...

Edit: Just tested it. Rendered a smoothed teapot, zoomed in a lot. HDRI used is 18420px wide, loaded with VrayHDRI node. First image is glossiness of 1.0, second is 0.97.
this is all with the V-Ray defaults in a fresh scene, where it even says resolution of 512 in the DomeLight. Can't spot any difference. As I said before, this parameter should be hidden from the user.
Maybe this really is a bug, John.

[Wilyman]

Thanks Oliver.
Yours seems to be working perfectly, and I haven't noticed any issues in the hundreds of shots I've done prior to this week, so I've got no idea what I've done to make this happen.
I guess I'll start the next scene from scratch and hope for the best!

Cheers,

John

[kosso_olli]

Alright. Did you try typing that one-liner into the listener, though?