sun color

[Laurent]

hi,
how do I change the strong yellow cast that the physical sun has?

[DanieleF]

Use a physical camera to render the image and set the white balance appropriately (for example the same tint of the sun).

Cheers
Daniele

[Laurent]

Ok, fine for a quick work around but obviously this will affect all other shaders, if we're talking about dozens that can't be very efficient.

[stefan]

you can use any distant light as a sun.

overall the physical sun is preety much what reality is. this comes at least from some sience papers from any univerity. forgot the link. it was also the one used in maxwell.

i personally love the vray sun,
but if you dont like it, a custom light and a hdri dome do also noce things:-)!

cheers
stefan

[Franz78]

and very important is to set the correct value of turbinity, try to set it 0 or 10 and you can drive very quikly the color of sun.

best franz

[Tong]

stefan

http://www.cs.utah.edu/vissim/papers/sunsky/

[Laurent]

Of course the sun color color has been declared yellow by some university, but could it be too much to be able to change the sun color just in case we aren't commissioned to work for the before mentioned university?
can't we just get the "white option" I swear not to tell "nature" or "the lancet".
no Scholarly paper will have to know.

[Tong]

sun color color has been declared yellow by Universe :D

You see? physical sun created, not to fake physical sun ;-)

it`s not like you can push the button and sun will be the color that you want, no. For that, use for example IES SUN ;-) or different type of light.

Here examples of sun color and brightness:
http://www.spot3d.com/vray/help/150R1/examples_vraysun_sky.htm

you see sun can be on Height (morning,day etc..), in place (Alayska, Africa etc..), with different atmosphere etc..

I think you wanted that type of light?

http://www.spot3d.com/vray/help/150R1/images/examples/vray_sun_sky/s03_render_Z_6000Above_def.png

[stefan]

the physical sun wouldnt be physical if the ciolor would be changable. this system is very fine calibrated.

if you want another color just use a norma light as sun:-)
the physical sky is not a must.

p.s. thanks tong for link

cheers
stefan

[Laurent]

my apologies.

thanks tong, great link.

[Tong]

my apologies.

nothing to apologie. Many years Cinema4D users use fake system with omni, spot, infinity light to make render be like real foto, so nothing unusual that your trying to make it simple and like always - fake, but now with physical things, i mean sky, sun, camera, ies (watt system etc..) lights,

No fakes, Just real life. (c) Nike ;-)

[InTheCity]

The Sun can have an unconvincing brightness when used in conjunction with '(hsv/)exponential' mode, and the 'Brightness multiply' is left at the default: 1

The exponential mode is a color mapping mode you'll likely find yourself using a lot of, especially as 'linear multiply' can blow out your colors completely.

Increasing the 'Bright colors multiplier' can even out an image.

Not to put Fluffy's work down, if you look at this image from his gallery;

http://fluffy4d.com/wp-content/gallery/architecture/biosonic1_final3.jpg

I personally think the Sun color looks off (like in my left sample).

Although at this angle the sun certainly tends to look more 'yellow'.
I may have attempted to go for something more like the
image on the right which feels more balanced imho.

Or alternatively, adjust the Turbidity and ozone to your liking as suggested, it all comes down to personal preference I guess.

http://www.project1media.com/vray/expo.jpg

[stefan]

looking at your sample i think yoou use the colormapping in a unusual way.
this is not like the physical sky look normally. only maybe in the very morning.

the sky for me brings cool results all the time. it needs good colormapping for me though. i always use expoentional 3.5 / 1.75 gamma 0.8 p.e.
this also makes the overall colors less saturated, which i prefer.

also looking at your image you have no outside. for realism ther should be a kind of floor, not too smallso that the diffuse light gets reflected.

cheers
stefan

[InTheCity]

I read your preferred exponential settings the other day.

I don't think there's a default that works every time,
they need to be adjusted on a per-scene basis like most other things.

As for seeing the outside on interior shots, that depends
on the perception you're trying to achieve.
I find the shots that try to mimic Photography are far more
convincing in terms of realism, than those that mimic
the eye and show both inside and out.

Like in this shot from my kitchen (excuse the mess)
exposure compensates to brighten the room.
In 3d when people consider both, it can look fake if not balanced just right.

http://www.project1media.com/vray/kitchen.jpg

or another example from the my bathroom

http://www.project1media.com/vray/bathroom.jpg


This image considers both and for me looks fake:
http://farm1.static.flickr.com/68/193286097_ae9f263650.jpg

and this looks far more photorealistic
http://farm1.static.flickr.com/214/505728661_5a29756e6d_o.jpg

[InTheCity]

Although, this just occurred to me.

In the first shot I displayed the intensity is overkill in relation to the time of day. It was just a bad example in terms of the position of the Sun.

[Tong]

it`s not a fake for your in 11.00 , but it fake for your in 15.00 where the logic? :wink:

great words: It was just a bad example in terms of the position of the Sun.

it`s old question about is sun is too bright or not? ;-)

it that more real

http://rp.foto.radikal.ru/0709/64/a17d910ba2da.jpg

than that?

http://rp.foto.radikal.ru/0709/b5/7cccc102f26a.jpg

[stefan]

in the city,
i think i just didnt understand what you want.

people produce highly superb images with this engine, mine settings where just suggestions, maybe not the most perfect ones, i like them for the things i do, of course i also tweak them to my preference.

it is just that if the sun is to bright or contrast to high you normally use colormapping.that i wanted to say. for indoors with big differences in light shadow you use another colormapping than with outdoor images p.e.

just try other things to find your way, vray gives you many possiblities. if you dont like physical sun the just make your own setup, also quite easy.
the sky is nice but is only an option from a wide choise of things.

there is no "toy story" button of course. a bit of training every new engine takes, also vray of course.

cheers
stefan

[Tong]

deleted

[stefan]

regarding the sun i found this here from vlado:

"By default, the VRaySun and VRaySky are very bright. In the real world, the average solar irradiance is about 1000 W/m^2 (see the references below). Since the image output in V-Ray is in W/m^2/sr, you will typically find that the average RGB values produces by the sun and the sky are about 200.0-300.0 units. This is quite correct from a physical point of view, but is not enough for a nice image. You can either use Color mapping to bring these values to a smaller range (which is the preferred way) or you can use the Sun intensity multiplier to make the sun and sky less bright. Using the VRayPhysicalCamera with suitable values also produces a correct result without changing the sun and sky parameters."

so it seems the default value is indeed stronger than reality by intension,
see above text and workflow suggestion by vlado.

here is more about sun in vray:
http://www.spot3d.com/vray/help/150R1/vraysun_sky_param.htm

cheers
stefan

[Tong]

Vray Sun + Sun Tag

KeyFrame Sun Tag = Time (One day length).

http://rapidshare.com/files/58476763/sunvideo.avi.html (mpeg4 only 478 kb ;-), if it to fast, you can "fraiming it" ;-))

just for fun ;-) and edu.

[rhodesy]

As i have pointed out before (but can't remember which thread it was in so sorry for repeating myself) - the Vray sun (or cinema interpretation) is just wrong :evil: I live in Newcastle in the north east of England (55N 1W)and i can tell you that at 19:00 yesterday it was light enough for me to cycle home with no lights on my bike. I am aware that it is a city which will have all kinds of light bouncing about the place but the majority of the light is coming from the sky. It would seem that as soon as it hits 7pm on the cinema light expression it turns the light off and the sky seems to turn off with it leaving a completely black render. Would it be possible to have a look at this as it isn't the most acurate for sun studies.

Cheers
Rob

P.S. I have just shown vrayforc4d to my bosses and they were very impressed so we are going to get it for work :D

[rhodesy]

Also i find the vray sun to be too blue - not yellow - like the example tong posted on the 1st page. What is the best way to de-blue shaddows?

[Tong]

rhodesy
White balance - allows additional modification of the image output. Objects in the scene that have the specified color will appear white in the image. Note that only the color hue is taken into consideration; the brightness of the color is ignored. There are several presets that can be used, most notably the Daylight preset for exterior scenes.

http://www.spot3d.com/vray/help/150R1/vrayphysicalcamera_params.htm
http://www.cambridgeincolour.com/tutorials/white-balance.htm
http://en.wikipedia.org/wiki/Color_temperature
http://en.wikipedia.org/wiki/Color_balance
http://www.lonestardigital.com/white_balance_solutions.htm
http://pictureline.webphotoschool.com/EVOLT_E-330_White_Balance_Outdoors/index.html

http://www.cambridgeincolour.com/tutorials/graphics/tut_WB_sardmen-incorrect.jpg http://www.cambridgeincolour.com/tutorials/graphics/tut_WB_sardmen-correct.jpg

http://home.comcast.net/~dougsmit/wbseries2.jpg

[rhodesy]

thanks Tong - worked a treat, vray has so much user power its great!

[Tong]

rhodesy the vray physical camera works like real camera, so the tricks for real camera works for vray camera. :wink: