Black Renders (solved)

[AlanBell]

I am consistantly getting black renders. I can see light on my objects in the perspective view. When I select the "No Decay" to it's checked state then I sometimes get a picture when I render but it's rarely anyting decent.

Running on Windows XP

Any Ideas?

Alan Bell

[Fluffy]

If you are using area lights, then make sure your light size or intensity is strong enough.
You can also increase the Vray camera sensitivity, by increasing the ISO parameter, decreasing the exposure and the f-stop parameters.
Usually, for interior scenes, you'll want something like this:
- ISO = between 400 and 800
- exposure = between 80 and 140
- f-stop (f number) = between 4 and 8 (be careful, it will have an impact of depth of field)

If you are using GIs, then add a little color in the environment tab, that way it will generate GIs from a sky dome automatically.

[simonw]

try setting your lights really high (and i mean really high, like 50000) and re-render.

also you could look into the photometric scale in the post-effect settings for the vray bridge. the default is 0.002 - try increasing that to 1. this seems like a global multiplier for the lights output.

the lighting in vray is very different from cinema - when using natural inverse square fall-off then your output will need to be increased.

the other thing i have found that effects the lighting is of course the exposure setting in the vray camera tag - turning that off can also help.

cheers, simon w.

[AlanBell]

Thanks I'll try all these things tonight.

Regards
Alan Bell

[stefan]

please take car your scenes is in real world scale

if you usse light that are very very big (like200x200m) you need to crank up the lightintesity also very much.

i pwersonall recommend not using m in the c4d units, as this makes the default area light 200x200m.

better to use cm

cheers
stefan

[Walli]

just a question, for better understanding: what is the reason for photometric scale in the post-effect settings set to 0.002.

Just because it works, or is there something that can help when dealing with scenes that you have to adjust scale-wise

best,
Walli

[stefan]

that is the real world setting to have it render correct. for pro users you can change that. p.e if your modell is to big or to small, but you dont want to scale the modell for some reason.

or if you want a light distibution as if the modell would be tiny, then you can change the scale in regards of the light solution.

but normally keep that value of course to get physical correct light distribution.

cheers
stefan

[Walli]

okay, so if we don´t touch this parameter and set the units in Cinema to centimeters (and of course model in centimeters), then we have physical correct lighting.

Thanks for the info!

[stefan]

exactly:-)

1m in realy should be 1m in c4d
1cm in realyity should 1cm in c4d
same with mm

all work m,cm,mm, ft ect you just have to remember to use realworld scale
cheers
stefan

[C.Smith]

I'd like to request for the new users that the next manual update has 'Use cm as your units!!" in bold red and caps. This seems to be a problem with many people i've been corresponding with including myself.

[AlanBell]

Could someone look at this and tell me where I am going wrong? It renders nice and black.


Thanks in advance,

http://www.box.net/shared/static/eb5o4ixkxl.c4d

[Pperezu]

The camera parameters...

In interiors, ISO camera without flash you need 400 or more, and shutter speed usually 50-100. F-number less than 8, usually 5,6

And the multiply sun light must be 1 almost

[DanieleF]

The photometric units setting is working only for the standard camera, because it's a way to normalize exposure of the image. That value (0.002) represent an exposure normalized for 1500 cdl.
Like i always said to our betatesters if you want to use the real vray's power, use always the physical camera and add the VrayLight tag to ypur light and use one of the photometric unit. With Physical camera you control the exposure directly from the tag (with ISO, Shutter speed, f-number parameters), and the benefit is a very realistic light diffusion.

Cheers
Daniele

[BVD2000]

please take car your scenes is in real world scale

if you usse light that are very very big (like200x200m) you need to crank up the lightintesity also very much.

i pwersonall recommend not using m in the c4d units, as this makes the default area light 200x200m.

better to use cm

cheers
stefan

thank tou....i alreay solved my question with your suggest :D