How to get better VRay renders (aka working in linear space)

[jujubee]

Here's some image updates now that I've figured this out. Thanks for all your help. Please disregard the floating bowl and wineglass as they're WIP:

[RErender]

Those look great Juju.

I talked to Goncalo about a month ago, He is alive and well. He said he doesn't have much time to do any Vraying too busy doing the Architect thing and playing Grand Turismo 4, He did say he was looking forward to 1.5

It is a shame that he is not active I've learned a lot from him.

[Gijs]

Looking good Jujubee! it's starting to pay off

[rpc212]

Fantastic! They look really great!

Just one critique, they do seem noisy, although that could be jpeg compression.

[jow]

Hi guys,been keeping an eye on this for awhile now,and i sort of follow

@jujubee how did u fix the washed out look? this is whats happening to me.

@flipside think your suggestion for a new step by step guide is a good idea.

one question i do have,when converting an old scene do i need to use colour correct on the lights as i do on the material's diffuse colour?

cheers guys.

[Gijs]

Gijs, is it correct to say that when doing your points, the gamma is burried in the image, so in fact it is not linear anymore? When I save the vray vfb, it looks the same in an image viewer too, but jujubee seems to have problems when he saves his image as hdr/exr, looking like there is an extra gamma 2.2 applied. (he doesn't have the general bitmap export gamma set to 2.2).

if you use gamma correct colormapping, then the gamma correction is burned into the VFB rgb channel. The gamma correction is not burned into the realRGB channel though.

@jow, did you real the article on my website (tutorial section)?

[flipside]

Ok that explains why juju had problems when saving out to hdr/exr.

If I save to hdr, and open it up in hdr shop, the image looks like it's just an LDR image with a hdr filename extension. I would expect when I lower exposure in hdr shop, that for example very bright windows would stay lighter than for example white walls. This is not the case. I tried all possible combinations of color clamping on/off, my hdr always reacts as a ldr image. Also in the vray VFB, exposure correction doesn't function as I would expect with a floating point image.

Are there some settings I should consider when I want to save out to a real hdr image?

[Gijs]

one thing to keep in mind is that when using gamma correction color mapping, the exposure control is not linear anymore. (linear as in 1 stop being half or double the amount of light)
About saving a hdr: did you save the framebuffer to a HDR? IIRC, this doesn't work. you have to check render output to file instead of save after rendering, then it does store the HDR information. Be sure to uncheck color clamping though.

[jujubee]

@jujubee how did u fix the washed out look? this is whats happening to me.

You are most likely double correcting (adding the gamma correction twice) in using gamma correct color mapping method by either:
1) saving out the VFB with an EXR.
2) saving from MaxFB with 2.2 Gamma in your Max preferences.

It should be noted in the tutorials, that with Gamma Correct Color Mapping and using 2.2 Max Gamma preferences that this method (versus Throb's method of introducing a curve) accurately displays in the plain VFB. Saving out to EXR from VFB or copying to MaxFB double corrects it (often seen by a washed-out look.)

So the key is when lighting your scene, light your scene so that it matches the plain VFB results. Then you can save out to an 8bit image.

[jujubee]

Just one critique, they do seem noisy, although that could be jpeg compression.

These were just test renders at low quality. I should also note that NO post-processing was done. The point of the last image post was to show better color-transmittance, exposure, and light fallofff with the Linear Workflow method.

[jujubee]

@flipside think your suggestion for a new step by step guide is a good idea.

Here's my simplified breakdown in four easy steps - #1 is optional:

1) You should calibrate your monitor to 2.2 Gamma Workspace. This is independent of working in Max but relates to improving quality overall. Information can be found at the AIM-DTP website and is very worth taking the time to read.

2) Now for the workflow. Set 'Max Gamma' (under preferences) to 2.2. Set 'Bitmap Input' in same window to 2.2. Leave output to 1.0

-Bitmap input means that when you import bitmaps into your diffuse swatches, they will already be corrected to the new working space so that you don't need to use ColorCorrect plugin on these particular materials. This is your choice - Flipside likes to not set the bitmap input to 2.2 cause he likes to manually use Colorcorrect on all his materials. I personally think it's more work. *Just note that setting the bitmap input to 2.2 adversly effects HDRs/EXRs (if you plan on using them.)

3) Convert diffuse material slots to new workspace. It only takes a second or two for each mat. In each diffuse that you use, right-click your Diffuse vray color swatch and hit 'copy.' In the blank square next to it, click and choose ColorCorrect (a free plugin which you should install.) Paste the color you copied (right-click paste) into the the red ColorCorrect swatch. Set Gamma in this same rollout to 2.2.) Done.

4) Set 'Color Mapping' in Vray Rollout/Render dialogue to 'Gamma correction' Values should be '1 (dark)/.45454 (bright).'

5) Render your scene to Vray Frame Buffer (VFB), not the Max Frame Buffer. The VFB now displays the final image without having to change/add anything. If it is too dark, turn up your light multipliers and rerender.

My big fear is that by having simplified this, people are not going to understand 'why' this works better. I suggest rereading the other posts and tutorials for a full understanding.

[jow]

@ Gijs,ya read your article quite a few times(thanks for sharing).ive followed what you've wrote and results are good.

@ jujubee, its not double correcting,i tried that to see what the outcome would be,

i think the problem is the scene im using was originally rendered using intensity exp. CM.and its got alot of colour bleed.
now using this method im not getting the bleed,i need to increase the colour of the lights....I think anyway

im gonna fire of another test and see what happens..

[jow]

cheers jujubee,after reading your last post i know im using the correct work flow.

easy when you know how..

[timmatron]

I think this is really going to change how a lot of us work. It's hard to see the advantages at first, but I'm doing my first interior using this method and so far it's giving some nice results. Now, I have to educate and get the rest of the office using this technique - THAT will probably be the hard part!

[jujubee]

Now, I have to educate and get the rest of the office using this technique - THAT will probably be the hard part!

Shhh! At least make yourself look better for a few years - this way they dont fire you and you get better raises. Or give credit to me as I live around the corner from you so I can get a high-paying job there... (this had crossed my mind before simplifying the steps.) I don't want my 'competitors' in this city running me out of town...