hdri glass problem

[Lebjos]

hi,

 

I have a problem when I go to render using the GI Environment (skylight) overide, and the reflection/refraction environment override both with vray hdri and a selected hdri spherical environment map in the slots to the right. However when i render it makes the glass in my scene black so you cannot see through it, but everything else remains the same, im confused as to whats happening, any thoughts would be great.

 

josh.

[dagor]

try to use hire multiplier for HDRI.

[Lebjos]

i tried to do that, and it just started to reflect on the side of the glass. I have "affect shadows" checked on my glass material so I thought that would take care of the reflecting problem, but it didn't. I am wondering if its a combination of the vray gi and then the hdri that is causing the problem? Increasing the hdri multiplier doesn't seem to be doing it =(.

[Lebjos]

here are some small screenshots from each side of the glass. I dont understand whats happening with the hdri maps, and why they are creating these effects, im sure its some small thing that I havent done.

 

the bottom 2 panes of glass are a translucent material, and the top 2 panes are clear glass, just for clarification. What i dont understand is why the black is happening while looking through the glass on both sides.

[Joseph Petrino]

Are you using a Vray dome light for illumination?

 

I have had my HDRI's do weird things when I use that particular light.

[dagor]

did you use Vray phisical camera?

if so - increase HDRI mult in 500 - 1500 times )))

it`s not only reflection problem because HDRI also affect refraction.

just create sphere with full reflection shader - you wouldn`t see HDRI in reflection.

 

check image i`ve attached

i increase HDRI mult in 1OO times! and it still not enough. Actual HDRI more bright than refletion in sphere.

 

Why this happens?

1. RTFM about Phiscam Sun and Sky

2. in to word sound like this:

By default, the VRaySun and VRaySky are very bright. You use Phisca to compensate their brightnes (exposure in camera). But HDRI still in NORMAL brightness. You phiscam affect on HDRI to and it become more dark. You must compensate camera exposure for HDRI by increasing HDRI multimplier.

 

If you don`t use phiscamera - i`ll be very surprised ))), Send me part of your scene please. I`ll try to find mistake.

 

and do more test. it`s pretty simple to do some quick rendertest with different changes of scene.

[Lebjos]

hmm yah, im not using a physical camera, so i will try to bump it up huge, but when i did this things got way blown out.... maybe its because im using gi and hdri? i will send you the scene, thanks for the comments and help, much appreciated.

[dagor]

did you use Exposure control in Enviromet dialog?

still havn`t recive your scene...

[Lebjos]

weird i sent it to your email... ill try again... i tried playing with that exposure and the hdris... but i dont think im doing it in the right combination.

[dagor]

you can attach it in zip format here.

 

I never use max exposure control in Envirometn dialog.

I think it also affect HDRI.

Test it in new scene. Turn of exp control in env dialog. usualy work with glass is pretty simple, it hard to say what the problem.

 

i`ve recieve your scene. i`m goint to test it )

 

 

i`ve check it.

so, there is not big problem. all`s ok.

you have no enviromen for reflection \ refraction in glass and your HDRI is to dark and contrast. change you HDRI and test it again.

check image i`ve attached.

i`ve built simple enviroment for reflection refraction. where my enviroment reflect\refract in your glass - there is not black areas. where your HDRI reflect refract in your glass - there is black areas. i`ve change HDRI to more colored.

 

i`ve touch nothing except HDRI in your scene.

 

so, build more complex enviroment or change HDRI.

 

hope it help`s you.

[Lebjos]

so i have to place my hdri map into a slot in my glass material to get it ot reflect and refract?

 

ahh thank you!!!! I realized that I hadn't turned the gamma up to what I normally use because I was using the VrayHDRI as the base material. I feel so dumb! Thank you so much for your help though, I also turned my HDRI up a little more and that is giving better results.... what values do you normally use if you aren't using a physical camera?

 

thanks so much for the time and help!

 

Josh

[dagor]

leave it in Vray enviroment section.

i`ve send you some hdri, it`s low res, but anyway try it.

You use max 8 or 9?

What is your vray version?

[Lebjos]

max 8 , vray 1.5 rc2 ... ok thats where i left the hdri map.

 

thanks

[Lebjos]

is the right most check box what you can check off if you dont want to see the map? I think my problem was that the black bottom part of the HDRI was reflecting on the glass.

 

Its possible to get the lighting but not see the map in the background right?

[dagor]

yes it`s possible.

 

Put HDRI in GI overriede and don`t put it in reflection\refraction override.

But you will have black color or map from max enviroment dialog in refl\refr glass ))

 

the best way imho is to build proper inviroment near your glass.

(am i right that you do exterior?) or use HiRes HDRI. Tweak hdri after you set up camera for best result.

 

and one more thing )) http://www.spot3d.com/vray/help/150R1/

there are alot of useful info ))

[Lebjos]

yes, i think the thing im avoiding is building a studio setup around my detail model to eliminate the black reflections. I'm mostly just trying to get some sort of a lighting/contrast off of the glass so that you can tell its glass however i dont want some insane reflections that distracts you. The render is going to go on one of my final boards for my architectural presentation. I want the rendering to just describe (show) how the detail looks in 3d. I thought that using hdri maps would be an easy way to get the glass to stand out as glass, but I think i created more problems for myself that way =). thanks for that site very helpful.