What's your best method of using sun and HDRI?

[andybot_cg]

I thought I would share my visopt setting to solicit feedback on methods to use HDRI and sky environment together. There was a question from thomthom on the sketchucation forum, but though it might be good to bring it up here and get the input of the developers too.
Cheers!

Andy

[fpedrogo]

I made a video long time ago showing my method to combine HDRI + sun. Here is the link
http://www.youtube.com/watch?v=pqMoh...3&feature=plcp

Best

[andybot_cg]

Hey Fernando. Yes, this was discussed way back here:
http://www.chaosgroup.com/forums/vbu...U-beta-1-48-99

What I am trying to do with my setting is to use the regular GI to add extra illumination to the scene. In this setting I have, the HDRI background strength can be controlled. Now that I think about it, does the background color slot add any illumination to the scene? I'll play around with this and see if it is behaving the way I am expecting, or if I just totally misunderstood...

edit: harumph! I was totally mistaken (or at least mis-remembered my original motivations) - the env. background does not add any illumination. Using the blend helps control the background strength, and gives a slot for the texsky, but beyond that, it's not doing anything different than what you already explained. Oh well, thanks for pointing me in the right direction at least...

[Jackson_cg]

I know this thread is old, but I just watched Fernandos video again and one thing I've never understood is how applying a TexSky in the Reflection slot (and then unchecking it) can cause V-Ray to use a blend of HDRI (in the GI slot) and the TexSky V-Ray Sun as the GI lighting? I can't argue with the evidence in the video, but just can't understand how (or rather why) TexSky in the Reflection Slot contributes to GI.

Even if this is the case, using this method how would one go about applying a blended HDRI/V-Ray Sun GI while using a different HDRI in the Reflection Slot?

My workflow for blended HDRI/V-Ray Sun GI has been to create a blend of about 0.01 TexSky and 0.99 HDRI (LDRI works too) in the GI slot. Trouble is it takes a load of experimenting to find the balance between the GI multiplier, the V-Ray Sun Intensity (usually below zero) and the Colour Mapping Brightness Multiplier to get a satisfactory blend without horrible burning and/or blue or yellow colour casting.

[andybot_cg]

I believe the point of the texsky in the reflection slot is to have a place where you can edit your sun settings. If you just have default checked, and hdri only in your env, then there would be nowhere to edit the sun settings.

[fpedrogo]

I know this thread is old, but I just watched Fernandos video again and one thing I've never understood is how applying a TexSky in the Reflection slot (and then unchecking it) can cause V-Ray to use a blend of HDRI (in the GI slot) and the TexSky V-Ray Sun as the GI lighting? I can't argue with the evidence in the video, but just can't understand how (or rather why) TexSky in the Reflection Slot contributes to GI.

The texsky in the reflection slot is to control the parameter of the default light in the global switches. The default light it is just a yellowish direct light if you use it by itself. It doesn't have sky properties. By using the textsky in the reflection slot you are adding sky/sun properties to the default light. Then you have to disable it, because you don't want to use it to override the HDRI reflection. Again, the texsky on the reflection is just a trick to add sun/sky properties to the default light.

Best

[Jackson_cg]

Thanks Fernando, I remember hastily watching your video when you made it a couple of years ago, but the thing with GI being controlled from the Reflection Slot threw me off and then I forgot about it.
It still seems extremely illogical that GI can be controlled in this way, but a workaround's a workaround so I'm happy to benefit from your fantastic tip!

One thing still eludes me though: I often use LDR jpg panoramas as backgrounds and need to add the same LDR in the Reflection Slot with a higher multiplier to get "realistic" reflections . I guess that when using your trick there's no way to add a separate Reflection Map... or can GI TexSky be controlled via the Refraction Slot instead?

[ValeroStudio]

Here is my method which is based off of Fernando's tutorial.

1. Place low res blurred HDRI in GI (Amount is usually set to 30 but depends on the HDRI)
2. Place hi-res clear HDRI in BG (this will take care of reflections).
3. Use TexSky trick to control the sun settings
4. Render with the alpha channel so you have the ability to swap out the BG in post.

[fpedrogo]

It still seems extremely illogical that GI can be controlled in this way, but a workaround's a workaround so I'm happy to benefit from your fantastic tip!

I agree with you that this is not a logical way. In the next build we will have the dome light in which you will be able to add the HDRI and then have the environment slots to do what ever you want to do.

GI TexSky be controlled via the Refraction Slot instead?

Yes, you can use the refraction slot then.

[ValeroStudio]

DOME LIGHT!

This is the best way to go for IBL. Stock up on some high quality HDRIs in prep for this next release, because you will never use this workaround again!