do you increase primary bounce for exteriors?

[d7man2000]

do you increase primary bounce for exteriors?

[diegofer_9]

I've done some exteriors and never had the need to increase primary bounces, I havent seen it done by others either. Are you not getting enough light in an exterior rendering? You should post an image and your settings

[d7man2000]

yes for exteriors:

so you just increase skylight only?

 

do you adjust dark/bright multipliers of color mapping?

 

 

you can go with primary bounce really high and I just wondered why because secondary bounce goes to 1 only

 

thanks.

[JamesTaylor]

Greg its probably best to post a sample image and your settings so people can can give you more specific advice.

[diegofer_9]

yes, post an image. There are always different approaches. You can increase the bounces and you'll get more light, but I think is better either to increase the multiplier of the light or play with the color mapping settings. You can also increase the skylight but sometimes it washes the image.

[d7man2000]

in this image I have :

 

skylight :1

primary/secondary bounces: 1

directional light: 1

color mapping: linear (dark/bright :1)

 

so everything is set to 1

 

what should I tweak and what will mess up the scene?

 

thanks.

[Christopher Nichols]

Trey reading this article... It explains your issues exactly:

 

http://www.throb.net/site_main/LinearWorkflow.html

[Sawyer]

Trey reading this article... It explains your issues exactly:

 

 

Or change your mapping the Gamma Correction and dark 1 bright .4545.

 

Excuse me, I will now hide while Chris throws something at me and corrects my linear correction method.

[d7man2000]

Christopher Nichols,

so linear is a way to go for exterior scenes?

 

 

Sawyer,

what do you mean?

"change your mapping the Gamma Correction and dark 1 bright .4545"

dark 1 bright .4545 Are you talking about color mapping multipliers?

mapping the Gamma Correction Are you talking about Gamma under Customize>Gamma?

[Sawyer]

Ok this is really important. My images have really improved since trying this and I held off on doing this for a really long time because everytime I read this I would get lost.

Basically your monitor does not display contrast correctly. The mid range of black is gone. To correct this you need to apply a curve to your images. You can do this 2 ways with vray.

1. (this is the link Chris posted) To apply the curve to the image. This is adjusting the image in the vray frame buffer. Once you save the file you loose the correction.

2. Apply Gamma Correction (as a color mapping option) with dark at 1 bright at .4545. This is applying the color correction to the scene so it is rendered in. The change is saved with the file.

Now most high end compositing programs have the linear color correction built into the viewing space so once you save the file and are out of max you don't need the curve correction. Correct me if I am wrong but I believe that in order to use this work flow you need to save to HDRI or another radiance file type. This represents a far more sophisticated workflow.

Anyway THIS IS IMPORTANT and really consider reading about this, looking over the website Chris posted and Chris's DVD for interiors. I had found that I had been fighting with vray to get good lighting in my shadows and this was a good solution.

 

I made realy quick curve adjustment in PS to illustrate.

[d7man2000]

where did you get the values for gamma correction in color mapping:

dark:1, bright:.4545 ???

 

I applied these values with "Clamp Output" enabled and image lost its life, scene doesn't have any contrast

I saved it as hdr and there are 2 options(anyway for both it looked the same)

 

It seems that when you save as hdr and take to Photoshop you can adjust only 3 parameters. There is one that can help quickly: Exposure

I can get decent contrast then.

 

I still don't understand the values 1 and .4545

 

 

 

do you do color correction after you render and you get satisfactory rendering right away with these values?

[Sawyer]

.454 is 1/2.2 1 divided by gamma of 2.2. The first time I saw it writen I saw 1/2.2 I thought it was dark 1 bright 2.2. Anyway...

[Christopher Nichols]

The whole point of a gamma of 2.2 is that it is a quick approximation of taking a PC into sRGB space. 2.2 for PCs and 1.8 for Mac (generally speaking). All images out of Vray are rendered in linear space (as they should be), you need to apply a gamma of 2.2 to your image (either in the frame buffer (good) or burn it into the image (also ok if you don't plan on doing fancy compositing).

 

To burn it in (the easier way to do it) you can use the gamma curve and apply a 0.4545 on the bright multipier (this reverse the gamma curve of the image giving you the correct 2.2... gamma 0.4545 = 1/2.2)

 

One of the issues that people have (and this may be your case), is that they start to light looking at everything in linear and because everything is dark they add all this fill light... then when they finally apply the correct gamma, all the balcks are pushed up correctly, and the image looks washed out.

[d7man2000]

when you set gamma to 2.2 in customize menu, the materials in material editor are all updated and it is hard to see what color it is

[Christopher Nichols]

when you set gamma to 2.2 in customize menu, the materials in material editor are all updated and it is hard to see what color it is

 

Technically speaking, they are the right color. If it seems very bright that is because the color is too bright. How can that be correct you ask?

 

Take a ball make it gray, render it in the viewport and see that it is the same color as the one in the material editor.

 

The other thing to keep in mind is that all your textures have to have be in the correct gamma space as well. If they seem very bright, open them in photoshop apply a gamma of 0.4545 on them save them, and reopen them. They should look normal.

 

I know this seems like a giant headache at first, but as it becomes clearer, you will appreaciate it more, and find that it works well.

[d7man2000]

thanks, I will use this technique

 

do you use G-Buffer output channels?

 

it looks like a great feature but for some reason I can only preview RGB and alpha in Frame Buffer. I enabled for example Shadows, specular and reflect but they don't show up in Frame Buffer.

[Christopher Nichols]

Sure I use G-Buffer output:

 

http://www.chaosgroup.com/forum/phpBB2/viewtopic.php?t=13818

 

You have to use the Vray Frame buffer.