PDA

View Full Version : Specular Problems



Wickster
07-19-2005, 04:44 PM
Hi all! I was trying out a lighting effect where a flat surface from a box reflects the specularity of an elongated area light. I wanted to create a gleam (i think thats what its called) on the flat surface.

But when I rendered it, the specular reflection came out very-very grainy.
Below is what my result was.

http://www.bmadigital.com/images/specprob.jpg

Any Ideas? Thanks in advance.

Axis3d
07-19-2005, 06:15 PM
Area lights can tend to look grainy. Under the Light's Properties Panel, try changing the Linear/Area Light Quality setting from 4 (default) to 5. Also, make sure you are rendering with antialiasing turned on. You can also try turning on Shading Noise Reduction (under the Global Illumination button). This tends to smooth out area light artifacts with shadows.

Fausto
07-19-2005, 11:54 PM
Hi all! I was trying out a lighting effect where a flat surface from a box reflects the specularity of an elongated area light. I wanted to create a gleam (i think thats what its called) on the flat surface.

But when I rendered it, the specular reflection came out very-very grainy.
Below is what my result was.

http://www.bmadigital.com/images/specprob.jpg

Any Ideas? Thanks in advance.

I know it's not what you're looking for but that does have a great cloth like feel to it doesn't it?

Wickster
07-20-2005, 12:08 AM
I know it's not what you're looking for but that does have a great cloth like feel to it doesn't it?

actually it does look a little velvety...kinda cool.

does anyone else know a better and by better imean "easy," way of creating a moving gleam on a reflective logo?

maxxwv
07-20-2005, 03:59 AM
I did this a while ago - make a black and white image map (black background, white stripe down the middle). Animate the stripe moving over the logo. Then, use Corona with the Specular channel as its' input to make the glow. You may have to fiddle with the settings a bit, but it should give satisfactory results. That and you get more control over the actual glow, as Corona allows you to select shape and set strength and stuff...

HTH!

Wickster
07-27-2005, 04:43 PM
hmmm, i tried all possible situations (that i know of) and i still get this wierd grainy effect on where the lights' spec suppose to shine.

is this a hardware problem, bug, limitation or i'm just missing one little step that when somebody figures it out i'd slap myself silly for not thinking about that. :foreheads

here is another sample of a different scene with the same problem:
http://www.bmadigital.com/images/spec.jpg

Surrealist.
07-27-2005, 08:24 PM
Thought you'd have this solved by now. Here is some information that may be a help when setting up your scene:

The global Illumination setting of "shading noise reduction" will take care of most grain problems of area lights and even the soft edges of shadow maps. It aslo of course helps radiosity grain.

Area lights have a distance/size to object ratio that you can use to control the softness and resultant grainyness of a shadow (as well as over all image).

The larger the light relative to the distance from the object the softer the shadow (and the more grain - even without shadows) . In otherwords, if the light iis close it should be relatively small for a sharper shadow(or less grain). You can control the softness then, by making the light smaller or larger and moving further or closer.

If the light is kept the same size and moved far away, the shadow will become sharper. (less grain over all)

If the light is kept the same size and moved closer the shadow will become softer. (more grain over all too)

If the light is kept at the same distance, a larger light will produce a softer shadow and a smaller light a sharper shadow. (more and less grain)

If you are using area lights this info should get you there. Also have you tried usuing a different light type.

Silkrooster
07-27-2005, 09:13 PM
Is this kind of what your looking for?
Silk

toby
07-28-2005, 12:23 AM
I recommend taking the grainy bump map off of the surfaces...

And you shouldn't judge grainyness before using anti-aliasing.

Wickster
07-28-2005, 10:32 AM
Thanks for the Help everybody! I'll give it one more go.


Is this kind of what your looking for?
Silk

:eek: YUP Exactly. Could you post your settings. Thanks!

Silkrooster
07-28-2005, 08:22 PM
Attached is the scene for you to look over. The gleam was created with a gradient image and applied to the specularity channel. Most lights will work with this. Since you were using an area light I set this one up with one. The intensity of the light is at 55% adjusting this value will increase or decrease the hot spot.
Hope this helps.
Silk

Wickster
07-29-2005, 12:47 PM
You rock, Silk! :rock:

Thanks!