Is there a 'correct' way to do VRay Sun/Sky?

[RyanSpaulding]

I'm looking to jump back into improving my VRay skills and haven't worked much with it since 1.47...so I'm new to the sun/sky thing.

 

What I'm finding is there seems to be a ton of different ways to do the sun. Is there a 'best' way? Some drop the sun intensity, some just change physical cam settings, some say dont use physical cam...arg.

 

So is there a 'best' way?

[Sawyer]

Don't use the physical camera if you are not familiar with real physical cameras.

 

This is my work flow:

I set up the sun light light and reduce it. I can't remember what I reduce it to say its .01. Then I can render perspective views of the building to give me modeling and texture feedback. Then when things are looking good I will set up the physical camera, pump the light level back to 1.0 and adjust the camera settings as I need.

[aaron-cds]

The lele method is the best method I've found. There's an increase in gi quality and a 20% decrease in rendering time, it's win win. All you have to deal with is making sure all of the materials have the .255 output multiplier.

 

http://www.chaosgroup.com/forums/vbulletin/showthread.php?t=36359

[RyanSpaulding]

Nice. 2 different methods. Anyone try any other ways? Curious as everyone seems to have a different method.

 

Sawyer:

Wouldn't your approach slightly change the look of the materials by drastically changing HOW you're brightening the scene?

 

aaron:

I'll look more into this...it seemed the most daunting of all the different ways to accomplish all this. Thanks.

[aaron-cds]

Once you have a grasp on the theory, set up a default scene with the sun, camera and settings. That's what I did. I could share that scene but you wouldn't learn anything

[Sawyer]

Yes the approach I use will have a variation and knowing that I don't really do much material work until I have a camera view. I am really just talking about test rendering the views that don't have the physical camera's built in exposure settings applied to it.

[RyanSpaulding]

That lele way of working seems to work extremely well from the video.

 

On first run-through of the tutorial, not sure I understand what exactly he's doing with these formulas he uses...and what the point of doing all that work is. He also doesn't go into using image maps...just the vray color maps. I'm sure there is some place to put that .255 multiplier...

 

I'll keep plugging. Once I get this down, I'm doing a sun/sky/cam setup video tutorial that will be quick and to the point.

[JamesTaylor]

That lele way of working seems to work extremely well from the video.....

 

He also doesn't go into using image maps...just the vray color maps. I'm sure there is some place to put that .255 multiplier...

 

it works brilliantly, as aaron says better gi solutions and quicker render times!!

 

just adjust your rgb output value in the bitmaps output properties to .255... you can also adjust this value to affect the map in your render afterwards too.

[aaron-cds]

I had to watch them three times. Change the RGB Level from 1.0 to .255 in the Output section of the bitmap.

[RyanSpaulding]

So from what I gather, I can do the following:

 

In Preferences > Gamma & LUT (optional)

 

1. Enable Gamma/LUT Correction

2. Set Gamma to 2.2

3. Click on 'Affect Material Editor'

4. Set Input Gamma to 2.2

 

And then, the process:

 

1. Add VRay Sun - leave intensity at 1.0

2. Add Physical Camera - set ISO to around 20-40 range

3. Set white balance (lt peach for exteriors - (20,55,245)

4. Color Mapping - Turn off 'Clamp Output' & 'Sup-Pixel Mapping' (Gamma 2.2 if using VRay Frame buffer)

5. Make sure all materials have an RGB multiplier of around .255

6. Tweak ISO on camera and Render

 

Obviously, each scene will vary a bit, but this should be a good starting point for good exposure. This theory goes more into real-life properties and that materials are darker than what we see with our eye because light hits it...and this is more of a trick to get it to behave more naturally.

 

Is that about right, without getting too technical?

[aaron-cds]

I don't have gamma correction enabled. The rest is correct. Basically, if you use a pure white color set to .255 as the material overide you can color pick the area in the rendering that is perpendicular to the rays of the sun to confirm that the float value is at 1.0. You can fine tune the ISO or f-stop value to get the float value at 1.0. Be sure to set the white balance on the camera for the scene. It makes a big impact on the overall coloration of the scene.

[RyanSpaulding]

Excellent.

 

Any specific time I should white balance the camera, or doesn't that matter?

[aaron-cds]

If you're using 1.50.00 there are presets for the white balance. For earlier versions you have to manually set the color. It's kind of fun to experiment with. Here are some examples. The file names indicate the white balance color.

[aaron-cds]

Here's two more examples.

[RyanSpaulding]

Nice examples. It definitely makes a huge difference in the final render.

 

So I'm assuming you have your vray sun attached to the daylight system then? So that you can pick the time and all that? I was doing it manually so far. I saw some tut somewhere about doing that.

 

Appreciate the help aaron. Tons.

[aaron-cds]

You're welcome. I don't have the sun linked to the daylight system. I usually place it where it looks the best for the scene. I do try, at least, to get it somewhat close. Linking the vraysun to the daylight system is easy using the link geometry tool. Just be sure to turn off the daylight light object. Once the vraysun is linked you can set the time for the daylight light object and the vraysun will follow.

[RyanSpaulding]

Ah, I'll likely just wait until I need to do a solar study for that one.

 

I've got a nice starting point right now that I've saved out. Thanks again. It's been so long since I've used VRay...the 1.47 era.

 

Onto.....displacement grass!

[RyanSpaulding]

Ok, I lied. One more sky question.

 

When I add a sun and tell it to automatically add the sky as an environment, I do in fact see this in the render.

 

However, in a bunch of tutorial vids I've seen (all w/o audio so there's no explanation), the user is supposed to drag this vraysky over to the material editor in a slot, click 'instance', click ok.

 

What is the purpose of doing that?

[aaron-cds]

Hey Aaron wouldn't it be easier just to choose the

Vray sun as your Sunlight type in the Daylight system??

 

Regards

Bri

 

Probably, I didn't know that was possible. Thanks. It's interesting how many ways there are to skin the cat.

 

Ryan - the older versions of vray did not automatically put the vraysky in the environment slot.

[Spooner04]

Ok, I lied. One more sky question.

 

When I add a sun and tell it to automatically add the sky as an environment, I do in fact see this in the render.

 

However, in a bunch of tutorial vids I've seen (all w/o audio so there's no explanation), the user is supposed to drag this vraysky over to the material editor in a slot, click 'instance', click ok.

 

What is the purpose of doing that?

 

I think you instance your vray sky into the material editor so you can adjust the parameters in the material editor. It should be good to go with the defaults, but if for some reason you want to adjust the few parameters, that's one way of doing it.

[Billabong]

Ryan It would be nice to see a little tut on this when you do figure it out.

[RyanSpaulding]

Ryan It would be nice to see a little tut on this when you do figure it out.

 

Here's the process if you missed it:

 

In Preferences > Gamma & LUT (all optional)

 

1. Enable Gamma/LUT Correction

2. Set Gamma to 2.2

3. Click on 'Affect Material Editor'

4. Set Input Gamma to 2.2

 

And then, the process:

 

1. Add VRay Sun - leave defaults

2. Add Physical Camera - set ISO to around 20-30 range

3. Set white balance (light peach for sunny exteriors - (20,55,245)

4. Color Mapping - Turn off 'Clamp Output' & 'Sup-Pixel Mapping'

(4 note: Gamma 2.2 in Color Mapping if using VRay Frame buffer, 1.0 if using max's)

5. Make sure all materials have an RGB multiplier of around .255

6. Tweak ISO on camera and Render

 

This gave me a very nice starting point. It's essentially a stripped down, less precise lele workflow. It'd obviously be better to go through and understand what's going on in this method, but this is good enough for me (for the time being)

[Billabong]

I understand everything but the RGB Multiplier part. Right now i have about 40 different mats in one scene. Does this mean I need to go to the output of each and every bitmap and change the out from 1.0 to .255 or is there a quicker way

[Ray]

I understand everything but the RGB Multiplier part. Right now i have about 40 different mats in one scene. Does this mean I need to go to the output of each and every bitmap and change the out from 1.0 to .255 or is there a quicker way

 

Lele has a link to a script here:

http://www.chaosgroup.com/forums/vbulletin/showthread.php?t=36359

[Billabong]

thanks for the link. ive done the suggested settings and I have taken my iso to 25, which made my scene completley dark, to around 200 , which is still making it look like a night scene, Ive changed my color mapping to Linear and exponential, using the vray frame buffer, but to no avail. still dark, I have also tried changing my f number from 8.0 to 5.6 and changing the shutter speed to 25 from 200, it does nothing. the only thing I haven't messed with yet is the vray sun and sky