Exporting an HDRI map fro Vray

[sumario]

I wan to export a scene I have in HDRI format so I can later use to illuminate characters. Anybody know how to go about this?

Thanks,

JP

[travistlo]

I Think what you need to do is render the scene in various exposure settings. Then use an hdri program to put them together.

I think you can treat each rendered image, and a "standard" photograph image.

http://www.debevec.org/HDRShop/
http://www.debevec.org/HDRShop/tutorial/tutorial3.html

Travis

[sumario]

Thanks for the info, I knew that. But some programs like Brazil have this function incorporated and export an HDR image from the rendering. I wanted to know if Vray had this functionality as well.

JP

[natty]

why cant you save your rendered image as an HDR .. ?...works for me

[sumario]

I can save it as HDRI but it isn't true HDRI. When I open it in HDR Shop you can see that it is not true HDRI because when it darkens or lightens it looses all the detail. True HDR images retain detail.

JP

[natty]

true ... but you can still light a scene with it ..

[DaForce]

Well then just save it as a JPG or something. Does the same job.

There is no point saving things as HDRI unless it is comprised of many different photos/renders/pictures all with different resolutions. Which you need to do in Hdrshop anyway.

Just because you rename a GIF to an AVI doesnt mean it is an AVI

[J_Bug]

DaForce, that's not how it works. VRay uses HDR internally. You should be able to save an HDRI from VRay and it work fine. A JPG isn't going to work anything like an HDRI.

Turn on Unclamped color in the G-Buffer/Color mapping rollout.
Put a camera in the center of your scene.
Change to Type: Box in the Camera rollout and your output aspect ratio should be 3:4. Then Save as type: Radiance Image File

You'll also need to have the SF HDRI I/O plugin if you're not using MAX6. I guess it was included with MAX6 though.

WHAT THE ....
I just tried it and it doesn't work now it must have something to do with this new MAX6 plugin.

Guess it's one for the wishlist or maybe another reason for the VRay EXE project

--Jon

[samuel_bubat]

Don´t forget, that your scene needs a high dynamic range lighting.
If you just have standard lights with multiplier 1 and an environment
that is not brighter than white, you won´t get a good dynamic range
inside your output hdr !!

So if you want hdr pixelvalues of .. for example 20 inside HDRShop
You will need an omni with multiplier 20.

[DaForce]

so your saying if you render a scene with vray and save it as a JPG and then render the same scene and render it as a HDRI there will be a difference?

Like the HDRI will act like a Debevec HDRI in HDRshop as long as you have Unclamped color turn on in the g-buffer?

I cant see how that would work....as a hdri is made of lots of the same image with different exposures (thats what i meant when i said resolution in my first post) Taking one render wont be enough will it??

[J_Bug]

I'm saying that it should be the case and what Samuel said is true (though I've always thought it only worked with VRayLights ). But for some reason, using 1.09.03r, the exporter isn't working for me now. I did try to save from the MAX VFB so that could be the case. Yes, an HDRI made with HRDShop is compiled from multiple images but this is just how you make an HDRI from LDR images. VRay uses a dynamic range in rendering and can save unclamped colors. I haven't been too clear on how it all works with VRay though because you can use Color mapping without having to turn on the Unclamped color G-Buffer and I've always thought this is what Color mapping relies on. One thing that I have noticed though is that when using certain features VRay will automatically generate certain G-Buffer channels and you can see this sometimes if you duplicate the MAX VFB and check the channel dropdown.

My only assumption is that Vlado is working on some smart G-Buffer technique that may have something to do with the VRay VFB. I believe I've read in the past that he's had issues with the MAX VFB.

I also thought that maybe another G-Buffer like Material color should be turned on so I just turned them all on with no success in saving again.

Maybe Vlado has something to say on this. Is this something to do with the integration with MAX?

--Jon

[J_Bug]

Hmmmm,

If you save it with the Save File dialogue it works fine and generates two other G-buffer channels (Coverage and Sub-Pixel Weight) automatically
www.dtoxx.com/J_Bug/OutputTestB.hdr

If you save from the MAX VFB it dosn't
www.dtoxx.com/J_Bug/OutputTestA.hdr

--Jon

[DaForce]

Hmmm i seem to be getting the same results no matter how i do it. For me the JPG behaves nicer in HDRshop than the HDR render does...LOL.

Perhaps you could make a few examples for me, maybe a mini tut

I want to try something tomorrow to test something out...but now i must sleep.

EDIT....
Just saw your edited post after i made mine...doh...i will try them out now.

EDIT...EDIT...
In HDRshop both your HDRI's act and look identical...what am i missing??

[J_Bug]

If you go down the range (- key) you'll see that the lights visibly retain their color in the good one and in the bad file they just get muddy. So this is an indication of the high dynamic range and if I used this for an environment I should get shadows and good specular reflection, and all that good stuff, from the rendered lights .

--Jon

[sumario]

J_Bug, I looked at your sample images. You did get HDRI results. Can you please breack down the sequence step by step for me?

Thank you

JP