Blending HDRI and Sky?

thomthom · 4 Jan 2012, 18:58

hmm...

Well, what I am trying to address is the shadows from the Sun - I'm getting very dark shadows. I'd like to reduse the darkness of the areas in the shadows.

However, if I use a HDRI map only the shadows becomes so soft that I don't really get shadows around smaller objects like people etc which makes them look like they are floating.

I'm actually not bothered about soft or sharp shadows - but some way to control how dark the shadow areas are.

valerostudio · 4 Jan 2012, 21:36

You do get GI using my method because both the GI Color and BG Color have the HDRI applied to them. Your Reflect Color holds the settings for the TexSky, which you can tone down the intensity of the sun in there. Just uncheck it so it doesn't replace your reflections and turn on Default Lights which in turn turns on the Sun system. I guess you could use blend as well, but I thought there was a bug there.

Here is the tutorial Fernando did a while back http://youtu.be/pqMohzR5mV0

valerostudio · 4 Jan 2012, 21:39

Also, they are resolving a lot of the HDRI issues in the next release with a Sky Dome feature. Thank God. I hate that every time I buy an HDRI I have to open it in PS and blur it so it works. Pain in the backside.

thomthom · 4 Jan 2012, 22:06

Yea - I've not been able to get a result of Blend today.

And I'm really looking forward to the Skydome.

andybot · 5 Jan 2012, 01:44

I take that back about the environment background slot... doesn't actually work the way I thought. To get the blend right you have to adjust two variables:

GI multiplier for the HDRI
sun intensity for the texsky

Just like in Fernando's tutorial

thomthom · 5 Jan 2012, 09:31

@valerostudio said:

Fernando has a trick for this. Basically use the HDRI in your Envir and BG slots. Then put the TexSky in your Reflect Color, uncheck it to turn it off (Vray still remembers the Texsky settings), then under Global switches have Default Lights checked, this uses the sun settings that are hidden under Reflect Color to cast the shadows. Voila!

Golden!!!

thomthom · 5 Jan 2012, 09:40

hmm.... if you use a plain colour for GI you can also easily tint the general environment while have full control over your sky shadow.

I made the sky size 20 so I got quite soft shadows - like on a partially clouded sky which my BG HDRI display. And then I lowered the intensity and now the shadow areas aren't so dark. Perfect!

andybot · 5 Jan 2012, 09:56

Well, the issue is with reflections. I went back to the original model I was testing, and it was an issue of reflections, not lighting levels. If your background is too bright or too dark, you won't see the reflection of your environment map, or you might see too much. The blend helps control reflections only. Hope that is of some use.

thomthom · 5 Jan 2012, 10:05

I'm not seeing any problems with reflections. It appears to me that I see just the BG HDRI...

andybot · 5 Jan 2012, 10:07

OK. I was just explaining the reason behind my alternative approach. YMMV
the illumination levels still depend on the sun intensity setting and HDRI multiplier either way.

thomthom · 5 Jan 2012, 10:10

I guess it might depend on the Sky and HDRI settings - in my current setup it seems to work ok.

valerostudio · 6 Jan 2012, 15:01

It all comes down to workflow and what you are trying to achieve. I use Fernando's method and wait patiently for Sky Dome!

ali64risk · 29 Jan 2012, 05:59

hi everyone
I chose a picture for BG in vray option window
does anybody knows how i can reduce the size of image and make it repeat in the back ground?

chon · 30 Jan 2012, 07:52

Hello,

in the Texture Editor of BG settings, if you use a TexBitmap, in the UVWGenEnvironment, you've got a "repeat" option for horizontal and vertical settings.

ali64risk · 31 Jan 2012, 07:36

@chon said:

in the Texture Editor "repeat" option

yes but it is not working for me:
it is a reflect able sphere I rendered for you to see
I attached original picture and rendered pictures with 1, 5 ,20 and 100 repeat both in horizontal and vertical directions.
as you see when repeat number increases it seams picture goes to be zoomed more and more in the background!
why I can not see at least one picture in complete size in the background? while I want to see pictures tiled in the background!

andybot · 31 Jan 2012, 11:08

Perhaps try a repeat of 0.25 (this should give you 4 images across the 360 degree view)

chon · 1 Feb 2012, 07:39

Using background images, VRay maps an image on the interior faces of a sphere representing the sky with your scene in the middle of that sphere.
So, on your image, you've got to represent both north AND south hemispheres with the horizon on the middle of that image like that :

Hope it will help you...

ali64risk · 3 Feb 2012, 16:33

@andybot said:

try a repeat of 0.25

this is a 0.25 repeat... as you can see it is still one picture in the background!

ali64risk · 3 Feb 2012, 16:41

@chon said:

So, on your image, you've got to represent both north AND south hemispheres with the horizon on the middle of that image

i understood what you said...
but why i should do that? I mean what happens if don't do that?
and how it helps me too have a tile texture in the background?

andybot · 3 Feb 2012, 20:50

@ali64risk said:

this is a 0.25 repeat... as you can see it is still one picture in the background!
I guess that's slightly less bad Maybe it's time to look for a different environment image - there's just not enough sky in that one...