vHDRI and white dots..

[rfellers]

I've recently done a few animations using Hyperfocal's vHDRI. The dynamic range is so high that you do not need to place a sun into the scene - shadows are nice and crisp. I am using...

Linear workflow (Gamma 2.2, Don't affect colors (adaptation only) = ON)
Universal settings
Sub-pixel mapping = ON
Indirect Illumination = BF + BF

The problem is I am getting sporatic white dots, or hotspots in some of the reflections. Sub-pixel mapping is on, but since the sun is burned into the hdri I can't make it invisible. I thought I was having a problem with the reflection of the sun in the HDRI, but I discovered when I turn off 'affect specular' (not 'affect reflections') in my hdri vRayLight, the white dots disappear. This got me thinking about a few things...

1. I thought specular highlights only worked when you had a point light (I'm using a vRayLight dome with the hdri). Does it really sample the entire hdri looking for the brightest spot and use that as the specular point?

2. How necessary are specular highlights since they really are just faking a reflection?

3. Is there a better way to fix the white dots (other than turn off 'affect specular')?

Thanks,
Ryan

[MoonDoggie]

1. I thought specular highlights only worked when you had a point light (I'm using a vRayLight dome with the hdri). Does it really sample the entire hdri looking for the brightest spot and use that as the specular point?

2. How necessary are specular highlights since they really are just faking a reflection?

3. Is there a better way to fix the white dots (other than turn off 'affect specular')?

1. Are you sure they're specular highlights? To check easily, turn on the render elements VRayReflection and VRaySpecular and check the channels using the VRay Frame Buffer. My bet is they're probably reflective highlights. VRayLights emit specular as well. Speculars were created when there were only point lights .

2. I love them. Fake, whatever, doesn't matter to me. I always get better results when using specular lights (usually omni's set to only set to emit specular) to get the most out of my geometry's shape.

3. Try turning on "Sub-Pixel Mapping" and "Clamp Output" in vray's color mapping setting and this should fix them. (Note: this is posted about 100x on the forums already). See if that fixes it.

[rfellers]

It is definately specular highlights - I did render a VRaySpecular pass and the white dots were there, clear as day.

As I noted above, 'sub-pixel mapping = on' for all my renderings. I hadn't tried "Clamp Output", but after a few tests with it, the dots improved significantly (Clamp output = 2.5).

I'm still a little unclear about how dome vray lights emit a specular though...

[stevesideas]

Its funny you should start this thread. Im having exactly the same problems with the same vHDRI's. Ive rendered out the render elements and have found the dots to be in the reflection pass. My specular doesnt have them...maybe our scenes/mats are setup slightly different. I have tried turning on clamping, sub-pixel mapping but nothing works.

The only solution I can think of is to bring the HDRI into photoshop and reduce the sun exposure then use a vray sun aligned to where the HDRI sun is and use that instead. Other than that Ive been photoshopping the dots out.

note: I clamped my output to 1.5 and I still had the dots so im not sure whats going on there.

[vlado]

Are you sure they are not due to reflections of reflections of the HDRI map? Would it be possible to send me a scene with this effect to vlado@chaosgroup.com ?

Best regards,
Vlado

[voltron7]

I have seen these go away by using a different HDRI

[stevesideas]

I have seen these go away by using a different HDRI

Is that a solution or a fact ?

[voltron7]

It was just to suggest trying a different map to know if the dots are coming from it or not...
sorry for any confusion...

[Dariusz Makowski (Dadal)]

I had white dots tooo argh !!!!! Entire scened was full of them... wrrrr

[stevesideas]

I was only kidding. My sense of humour gets lost in text.

It would be a pain to not be able to use these vHDRI's as they are rather good. Plus they are fairly expensive. Maybe we should contact Hyperfocal...

[voltron7]

Sorry I missed the joke, my sense of humor hides out sometimes when I'm online...I have a Hyperfocal collection and it's been fine...but it must be a different one 'cause it's 3-4 years old

[stevesideas]

No worries Yes, the VHDRI pack came out not so long ago. I have one other Hyperfocal pack and all the HDRI's are fine when using them with Vray.

[stevesideas]

Ive just contacted the Hyperfocal team so hopefully they may shed some light on what we can do.