LWF...again...sorry!

[Logitek]

Hello,

 

I know this topic has been discussed a thousand times, here, on the chaos forum (which I don't have access anymore...I wrote them... waiting for feedback) and on many places over the Internet. I've searched and read many different explanations, tutorials, and videos that try to cover this subject, but now it seems like I have too many different information and I can't sort them out.

I'm only going to ask 2 questions because I know how complex a subject this is and no one could explain the whole concept in one small post... so here are the questions (and they might be very stupid or obvious, but my brains stopped processing all LWF informations it seems ):

- If Gamma is enabled and set to 2.2, "Affect Material Editor" is checked, and input gamma for the bitmap files is set to 2.2, do I also need to change something in the VrayMtl when I use a bitmap? If so, what should I do? Always put an "output" material in the diffuse and in the output, I place the bitmap and then set the RGB Level to 0.255? Or should I use a bitmap directly in the diffuse slot and in the Output tab, set the RGB Level to 0.255? (I would think these 2 options do exactly the same thing in the end)... or am I totally mixing this with the Vraycolor material here?

Which leads to my second question:

- if I want to only use a color (no bitmap) for my material, do I always have to use a Vraycolor material in the diffuse, and then set the RGB Level to 0.255? What if I enable the "Affect Color Selectors" in preferences (oops, that's a third question!)

 

If these questions were understandable, I would greatly appreciate your help on the subject. I would really like to work this LWF out before I decide to throw it away or not... I'm sure it must be good if so many people use it.

 

Thanks in advance! (I can provide Tylenol to those who will succeed in making me get this LWF thing )

[Devin Johnston]

Hello,

- If Gamma is enabled and set to 2.2, "Affect Material Editor" is checked, and input gamma for the bitmap files is set to 2.2, do I also need to change something in the VrayMtl when I use a bitmap? If so, what should I do?

No you shoulden't have to adjust the material if your gama settings are correct, they will show up accuratley. There is no need to adjust RGB levels in order to see any material correctley be it a simple vray color or a bitmap.

[Logitek]

So you're basically telling me that in order to use the LWF, all you have to do is enable the gamma correction to 2.2, check "affect Material Editor" and set the Input Gamma to 2.2?

 

If it was so easy, I think (I hope!!) I would have understood this before

 

I've watched these http://www.vrayelite.com/lele/leleTut.php videos about 3 times, but they don't cover how the bitmaps should be used/corrected.

 

I can't stand it when I don't understand something! I need to know! so I can go back to my old workflow...

 

thanks!

[Devin Johnston]

Go to customize/preference settings/gamma and LUT and set the following:

-Enable Gamma/LUT Correction

-Display Gamma 2.2

-Materials & Colors/ affect color selectors / affect material editor

-bitmap files / input gamma 2.2 / output gamma 1.0

 

That's it, your materials will display correctley as long as you use the Vray VFB, if you don't and you use the Max VFB then things will be blown out.

[Logitek]

That's it

 

Well, when I only do this, I get really bright uncontrasted results (when sRGB is on), or very dark (when sRGB is off).

Do I NEED to use VraySun/Sky/Camera in order for it to work properly?

[Logitek]

oh, and what's this 0.255 thingy then?

is that another method?

[WAcky]

I think the most confusing part of this all at the moment is that LELE didnt give any info on how to correct bitmaps. I am still confused with it as well. I have set up my scenes with Sky/Sun/PhysCam and have adjusted my iso to make the brightest white point in my scene a 1.0 float value. I've enabled all the gamma settings in max but i'm in the same boat as Matthieu. If you have to adjust a material using a VrayColor material and lower the output, then why shouldnt it be done on bitmaps??

 

Edit: And i totally agree with you in saying that reading through the monster LWF threads on the chaosgroup forums only gets more confusing. Reading other peoples confused posts only makes things worse.

[Fran]

Edit: And i totally agree with you in saying that reading through the monster LWF threads on the chaosgroup forums only gets more confusing. Reading other peoples confused posts only makes things worse.

 

It's tedious to read many of the threads over there because they often get hijacked by veterans of the board who are tired of the subject. So you have to wade through a lot of unrelated banter that nobody else is interested in.

 

Having said that, I managed to recently get some renders output with Vray using the LWF. I don't know if I did it right, but Matthieu, that is the way my studio contact describe it to me - enable gamma, etc. I didn't use the Color Correct plugin though. I don't know if that made a difference or not. I'm also not sure what the point of it all was, except it helped to reduce the burn of lightsources, while still staying with the Linear color mapping.

[WAcky]

I just had a read of a link that i got from another thread somewhere that i cant remember now. It applies to vray 1.5 so its current. It's probably the simplest explanation of the theory and the simplest instructions on how to implement it.

 

http://www.aversis.be/tutorials/vray/essential_gamma_01.htm

 

This does not however, deal with the physical camera issue/over exposure. Once i get home i'm going to see at what point this method and the LELE method meet in the middle without double correcting the issue.

[bijoy]

hi Logitek,

i was lost with this whole thing as well but i went back to one of the old sites that i used to frequent to learn vray and it was a good site for tutorials and stuff. its called aversis http://www.aversis.be/tutorials/vray/index.htm. im not sure if u have seen this site but it got me off to a perfect start. Hopefully this helps just go look for the 9. Gamma 2.2 setup in Vray and everything you need to know should be there. Good Luck.

[WAcky]

its pretty much...wait no...exactly what i posted

[alfienoakes]

its pretty much...wait no...exactly what i posted

 

That is a cracking little tutorial actually.. Everyone struggling with LWF should read it..

 

Glad you found that Bijoy............ sorry........James..

[Logitek]

Glad you found that Bijoy............ sorry........James..

 

Yeah, it's pretty straight forward and clear. Thanks Bijames

 

Only thing that is not mentionned (but in fact, is not necessary for this workflow) is the use of the VraySun/Sky/Camera... This is actually a totally other subject, and this is probably what threw me off.

 

Oh, in the Aversis tutorial, in the end he's talking about the ColorCorrect plugin. Now if we don't use this plugin, should we use the Output Material set with an RGB Level at 0.4545 to compensate for the 2.2 Gamma? (now I'm starting to speak like a Marsian, don't I! )

[WAcky]

Ok, the way im doing it is following that aversis tutorial. At which point you're in LWF. stop there and you're good. But if you want to use the Physical camera, then use the LELE method as well. Set up your scene, measure your whites, work out your correct ISO level and color correct your colours until you have the sky the colour you want + the whitest point in your scene at 1.0 float value. That's how im seeing it. Please please please correct me if i'm wrong because im still just making good guesses at the moment (i think...)

 

You may have read that since LELE's tutorials VRAY has been updated so his .255 colour output is now incorrect. Im using .45 at the moment, but it really comes down to what colour you want your VraySky at...

 

This is my workflow after using Vray for only 3 days so dont hate me if i have something wrong.

 

Good luck

[bijoy]

Hehe...not bad eh. the thing is about this tutorial is that...well...its a tutorial. Most LWF explanations out there is a bout theory. Losts of it as well. have i got the right settings for my renders with his methods...NO. there are a few lose ends here and there but this is the only 'tutorial' out there...telling you how to get a scene done...thats all we wanna know at the end of the day. what ive been doing though is tweaking and playing with the numbers. vray sky, lights, camera. its a whole lotta mess. vray 1.5 is nice, has a lot of control...but no one seems to grasp the whole concept...thats the problem. in all honesty, vray was doing just fine for me at version 1.47...less tweaking and research done. Any different in quality? To me, nope. my renders looked better because i was in control of the software. So until there is someone who is gonna come up with a decent tutorial on how to do renders(int n exterior) i would say dump it...dont fix what is not broken...or something like that. anyway good luck...i cant really answer the whites of .255 or the .455's...haha but if its killing ya dont bother. Go back to basics till someone comes up with a standard way of doing it. right now the whole thing is a mess.You will save more time as well.

[alfienoakes]

Ok, the way im doing it is following that aversis tutorial. At which point you're in LWF. stop there and you're good. But if you want to use the Physical camera, then use the LELE method as well.

 

You may have read that since LELE's tutorials VRAY has been updated so his .255 colour output is now incorrect. Im using .45 at the moment, but it really comes down to what colour you want your VraySky at...

 

This is my workflow after using Vray for only 3 days so dont hate me if i have something wrong.

 

Good luck

 

You dont HAVE to use Lele's method. I think things may have changed in the latest version of Vray, but you CAN still use it. The problem was with the physical sun / sky. I use the Physical camera and sky now, and have switched away from Lele's method back to standard vray mat's and its working for me.

 

Lele's method isnt incorrect.. dont let Chaosgroup hear you say that....

[WAcky]

you use a phys cam and a sky? what about direct light?

[alfienoakes]

Opps.. and the vraysun..

 

Although you can obviously use just a bit of GI.. but not always..

[WAcky]

i see. So do you still have a low ISO setting? but not as low as the LELE method? Im a noob at Vray so the LELE method was well explained and i just went with that so I'm trying to find out the other ways of doing it...

[alfienoakes]

Its all about getting to know how real world cameras and exposures work. Check out the "sunny 16 rule"

 

Someone pointed me in that direction and it was like a eureka moment, in terms of externals anyway.

[Logitek]

Hello Andy,

 

Sorry to reply so late. I've only been able to check out the "Sunny 16 rule", and to tell you the truth... it seems to me like I'm missing info.

Example: when it's sunny, I set the f speed to 16, then the ISO and shutter speed should be the same or just about. But how do I choose which ISO is good for my scene? Or maybe what this rule is telling me is that when it's sunny, the f-speed should always be set to 16, and the ISO and shutter are the value to change in order to get the correct exposure?

 

Thanks a lot Andy! this adds another parameter to the already too complex theory

 

(Should "Exposure" be checked or unchecked... I've lost my notes about this In which case does the VrayCam act like a standard cam?)

 

Thanks again!

[alfienoakes]

Have a quick look at this:

 

http://www.photokaboom.com/photography/learn/tips/054a_exposure_sunny_16.htm

 

Then have a play with a simple scene. If you turn exposure off, it will act like a physical camera with exposure off... Use a standard camera if you dont want all the settings that come with physical cameras.

 

then have a look at this:

 

http://www.fredparker.com/ultexp1.htm#EV

 

Dont get too bogged down in it, its more about knowing what the effect of changing the iso and the f number will have on your scene.. At least to start with..

[WAcky]

thanks mate

[crossccx]

Hello,

 

I know this topic has been discussed a thousand times, here, on the chaos forum (which I don't have access anymore...I wrote them... waiting for feedback) and on many places over the Internet. I've searched and read many different explanations, tutorials, and videos that try to cover this subject, but now it seems like I have too many different information and I can't sort them out.

I'm only going to ask 2 questions because I know how complex a subject this is and no one could explain the whole concept in one small post... so here are the questions (and they might be very stupid or obvious, but my brains stopped processing all LWF informations it seems ):

- If Gamma is enabled and set to 2.2, "Affect Material Editor" is checked, and input gamma for the bitmap files is set to 2.2, do I also need to change something in the VrayMtl when I use a bitmap? If so, what should I do? Always put an "output" material in the diffuse and in the output, I place the bitmap and then set the RGB Level to 0.255? Or should I use a bitmap directly in the diffuse slot and in the Output tab, set the RGB Level to 0.255? (I would think these 2 options do exactly the same thing in the end)... or am I totally mixing this with the Vraycolor material here?

Which leads to my second question:

- if I want to only use a color (no bitmap) for my material, do I always have to use a Vraycolor material in the diffuse, and then set the RGB Level to 0.255? What if I enable the "Affect Color Selectors" in preferences (oops, that's a third question!)

 

If these questions were understandable, I would greatly appreciate your help on the subject. I would really like to work this LWF out before I decide to throw it away or not... I'm sure it must be good if so many people use it.

 

Thanks in advance! (I can provide Tylenol to those who will succeed in making me get this LWF thing )

 

all you got to do is set all your gamma twice (2.2)... after u have to calibrate your monitor (lcd or crt) with a hardware tool, so you can exactly choose a desired gamma. maybe it a bit hard to understand... but i believe u will see the diffrence of your final image. thats it.. gut luck!