Yet another Linear Workflow post...

[Shimakaze]

I've been trying to wrap my mind around this concept and I think I have most of the facts sorted out but I'm still a bit confused by some parts of it. Can someone please tell me if I've got this right or not?

So to use LWF you enable Max gamma correction, set it to 2,2 (for a calibrated CRT monitor), set bmp input to 2,2 and turn on the mat editor and picker settings. Doing this brightens the mat editor previews but doesn't change anything in the viewports for me. then you either bake the gamma into the render output by setting the color mapping gamma to 2,2 or enable the sRGB button in the VFB for preview and save the picture without the 2,2 change...
So here's my question... it seemes to me I can never get correct renders (especially with the vray sun) without doing all this. I assume this is because the texture bitmaps are already gamma corrected for 2,2 and so are brighter then they are supposed to be? Does that mean that if you have a monitor that is calibrated for 1,0 gamma (my laptop for one) you still have to put in the 2,2 correction for the bitmap input?

[Blitterswitch]

Well, I don't know whether what I am going to write will help you at all but I can't bring myself to start yet another thread on LWF so I figure I will jump in on this one.

I have been reading up on the subject of LWF for the past 2 months and have been having no luck at all in acheiving any results which are worthy of sending out.

I have taken the advise posted all over the web and purchased a Spyder2 suite and calibrated my monitor to 2.2 gamma and 6500k.

Teamed up with this I have set the max preferences to gamma 2.2 and bitmap import of 2.2 leaving the output to 1.0

I am using color mapping of linear multiply and leaving the settings to 1.0, 1.0, 1.0 - I am using the sRgb switch in the vray frame buffer to show me the gamma corrected image.

All my color swatches in my material editor have a colorcorrect of 2.2 applied to them - they all look very dark.

As far I as can understand I have done everything that I need to do in order to produce images using LWF. Unfortunatly they are just so dark that I always have to take them into Photoshop after and increase the brightness significantly and also play with the contrast.

In my scenes I am using IES lights in the exact RCP configuration that will be installed and my scene scale is set to millimeters.

Can someone PLEASE PLEASE PLEASE offer me some advice. I would love to be able to get this going properly because I know that if I manage to get it working my work will be vastly improved.

Thank you in advance,
Marcus.

[tct70]

This sorted things for me...................

http://www.chaosgroup.com/forum/phpB...ic.php?t=19563

[Blitterswitch]

I have had another good look through that thread and I am still non the wiser.
My images have the same qualities as the second image in your examples. The major problem with this is that it looks like this AFTER the gamma 2.2 is applied!
I know that its not the case that the lights are too dim, I have done some renders with the multiplers set at 1000% and all that happens is that the colours become really over saturated and the image lightens a bit.
I know there must be something which I am doing to make it not work but I am at a complete loss as to what it might be.
Might it have something to do with how I am importing my textures in the material?
When I import a texture am I meant to select images own gamma, systems own gamma or specify another value all together?
Are the material slots meant to show the material in a state reflective of how they will appear in the render or are they meant to be darker ready to be 're-lit' in the scene?

[Clifton Santiago]

This is so simple, I think I need to do a tutorial on it. I'm doing one for a friend this weekend. You guys ever come to London?

[Shimakaze]

That sounds really weird. The only thing that springs out at me is that saving the picture from the VFB with the sRGB button on doesn't change the gamma of the saved picture. But if it looks too dark even in the preview then that's not the reason... Could you possibly have Max's built in exposure control turned on?

Anyway about importing textures, if I've understood it right setting the bitmap input option to 2,2 is the only thing you need to do. that will globally correct all the pictures you import so you don't have to do anything. (though if you want to import an image that's not 2,2 corrected you'd have to manually change the setting for it)

So can anyone confirm all this?

Britain is a bit far to travel just to learn this how about you make a video tutorial?

[tct70]

You guys ever come to London?

Keep meaning to attend the "London Calling" drinks............will make sure I put more effort in - not that far for me.

Besides, rekon I owe you a beer or two!

[Shimakaze]

I'm really just confused about one thing specifically. Do you always have to gamma correct imported textures regardless of what your monitor's gamma is and such in order to get correct results with v-ray?

[Clifton Santiago]

Right. Just set you input gamma for bitmaps at 2.2 and work as normal.

@Blitterswitch: Your swatches are dark because you are using the color correct plugin at 2.2 (which is inverting it so when it is rendered at 2.2, it is not double corrected). This is the same as working with the material editor set at 1.0

After you have set your material editor to a gamma of 2.2, just use your color swatches as you normally would. Only use the color correct modifier if you need to match a specific RGB value.

LWF in 3 simple steps:

1) Open a new file. Set your gamma settings to 2.2 as shown here:
http://www.gijsdezwart.nl/images/gamma-tab.png In Max, you also want to enable Affect color selector and Affect material editor

2) Work as normal*. MFB will appear as gamma corrected. VFB just needs to have the sRGB button clicked.

*Keep in mind your "normal" i.e. previous lighting habits will need to be altered because due to the gamma correction your mid-ranges will be lighter and you will need to use less light in general.

3) Save your rendering as a 32-bit EXR file. In PS CS2 or better, it will appear exactly as in your frame buffer. Or, with 8-bit formats (like jpeg) set Override to 2.2 in the save settings.

That's it. You can make it more complicated if you want with other methods.

Have you read the early LWF tutorials on this stuff? Also Chris Nichols DVDs have good info on LWF.

http://www.highend3d.com/3dsmax/tuto.../vray/147.html

http://www.gijsdezwart.nl/tutorials.php

[Shimakaze]

So I was right after all
Thanks! Just the answer I needed

[Clifton Santiago]

Oh, one other thing. There is a little bug in Max 8 (at least) with gamma correction. When you first set your gamma to 2.2, the MFB will still render as if at 1.0. Just save the file, close, and re-open. It should work fine.

The gamma settings are not file specific normally, so once you set it, all files opened will be gamma corrected. This is a problem with your older non-lwf files. Unless you are really familiar with LWF, I don't recommend you gamma correct your old files.

In that case you will need to switch back and forth. To do so (and get a warning dialog each time) you will want to click the "Load Enable States with MAX files" in the gamma settings.

Eventually all your current files will be LWF, so you can then disable this feature.

[Blitterswitch]

Right well I have followed all of you directions and I am still in the same position.

I have taken the time to take screen captures of everything so maybe someone could point out what it is that I am doing wrong.

Here goes! VRay settings first...







Next my Max settings...



Next my material editor...



Lightlister...



Viewports...




and finally my outputs in the VFB then copied to the max buffer.



Notice that the sRGB button is not on and the color mapping has 2.2. I am wrong to expect both the VFB and the max fb to match with these settings?
Also I apologise for the small final render, and also I am aware that I am using very low settings overall, this is purely for speed right now.

Thanks for all the advice!

[Clifton Santiago]

wow...

Most of that is not necessary to evaluate. Your gamma settings are correct.

Is the left one supposed to be the sRGB and right one not? The MFB should match the VFB with sRGB enabled.

If the left image is the gamma corrected version, you are overlighting your scene. Turn your lights down.

It must take forever to render with all those IES lights!

[Shimakaze]

Yes the max frame buffer will be different from the vray one. the Max one is affected by the global gamma setting so it always shows the picture as gamma 2.2. that won't affect the saved picture though. the vray frame buffer is better to use since you can choose to enable the sRGB option yourself.
Oh and there probably isn't any point in using environment skylight for an internal scene like that. might save you some rendertime to turn it off. note that the version you see with sRGB on is the one you should base the lighting on.

[tct70]

If I have it right the MFB is washed out because you have set the Vray gamma in Colour mapping to 2.2 as well. Leave it a 1.0 and forget using the Vray frame buffer.