2 HDRI + VrayDome light's question...matching horizontal rotation?

[danb4026]

I am using 2 dome lights, each with the same HDR image (not instanced). One is for enviroment/reflection and the other is light source. I want to to be able to horizontally rotate the lighting VrayHDRI and have the reflection VrayHDRI rotate equally. How can I link the the HDR maps to do this?

[cg_Butler]

Check out the Wire parameters options in this cracking little how to from Mintviz. It's eactly what you need. You can wire the rotation of the texture to the rotation of the sky dome. Happy days!

 

http://www.workshop.mintviz.com/tutorials/hdri-exterior-lighting-with-vray/

[danb4026]

Thanks Andy! Very informative and gives good results. I wonder which method is generally preferred....1) as in the link above, with vray sun matched to vraydome/hdri, or 2) using 2 dome lights with the same VrayHDRI, 1 for lighting and 1 for environment. I find 2 domes to be easier to setup although it does requires a high res hdr and some play with the gamma to produce good shadows. You certainly have the advantage of matching/direct light with method 1. I am interested to see who prefers what.

 

One change I would make to method 1, is to set the wire parameters to "bi directional" rather than one way. This way you can also use horizontal rotation withing the VrayHDRI parameters to rotate the dome and sun.

[cg_Butler]

I personally haven't used his method of linking VRaySun with a sky dome. SO I'm with you on the preference for two domes.

 

Bi-directional is a great shout! You should suggest it on the posts at the bottom to James. He'll no doubt update it to include that option too. He's good like that. I think he's a member on here too so might even see this! Or you could send him a link to this post and suggest to him to add it on to his workflow.

[danb4026]

For the sake of argument I uploaded sample renderings using the 2 methods. The first is vraysun/dome combo and the second is 2 dome lights. All of the HDRI's are set to multipliers of 1, as well as gamma 1, so as to be comparative. They both have the same HDR in the environment slot as well and the vray cameras have exactly the same setup. The real difference is obviously the direct light that the sun provides, and it dramatically changes the image. The question really is, whats your preference and which is more true to life.

[ARTE DELLA VITA]

i had an hdri that i loved to use but i could not get strong shadows from it no matter what tests i did with the gamma but the sky and look of the hdri was what i wanted so i had to use either the vray sun or direct light to give me the shadows i wanted for that exterior scene and there are other hdris that i have that really give me the shadows i want with just dropping the gamma value from 1 so i never needed other lights. So it depends on how you want to work, to change colors of lights in the scene is the real issue for me, either i have to play with the hdri color in photoshop first or color correct it in 3ds max which takes more time. mostly its easier to work with standard direct light because i change colors on the fly with very nice results and it is fast may i say and i can stil use the hdri to give me some color variation weak or strong.

[Nic H]

i dont understand a word of that ^

 

if you have good quality HDRI (guthrie) the lowering gamma trick works fantastically for harder shadows

its a bit tricky to get a sun to match with hdri lighting - looks too cg

much prefer if possible to use a single hdri

 

i do however often use 2 hdri - 1 for diffuse, the other for spec and reflect.