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View Full Version : Lighting troubles...updating??



Johnny
08-08-2003, 01:35 PM
I have been having trouble getting the performance out of my lights that I beleive I should be getting, with respect to objects' "catching" light.

I've tried moving the lights so that they were right on top of the trouble objects, cranking the intesity, varying the camera angle, making sure that the objects' surfaces were reflective, etc., but nothing seems to make those objects (glass) catch light.

any suggestions? Some of my objects DO catch light, are also glass, have very similar surfaces, and are all in a group together.

Johnny

toby
08-08-2003, 02:59 PM
what do you mean by 'catching'?
highlights? illumination?

Johnny
08-08-2003, 03:07 PM
Originally posted by toby
what do you mean by 'catching'?
highlights? illumination?

yes. both those things...two of my bottles are visible, but almost in shape only..almost as though they're flat. My lighting doesn't show their luscious glass surface, their fullness, their volume, the thickness of their walls, etc.

I've played with a variety of values of Specular, Diffuse, reflection, as well as the values of some of the shaders.

I have even exported the shaders of glass objects that DO catch light, and loaded them into these uncooperative bottles, and modified the color and bump to make them different, but these bottles still look flat..

I've placed lights to the side, to the back to the front, directly overhead, and right smack next to these bottles and I can't seem to get any variance at all...high intensity or low.

Almost makes me wonder if something about the scene just isn't being updated...


Johnny

toby
08-08-2003, 03:28 PM
make sure that your lights are not checked to exclude those objects, if you're using the BRDF shader you may have to go into it's settings and turn those lights on in there as well.

mlinde
08-08-2003, 03:54 PM
Are you by chance using 7.5b? There were troubles with a number of surface settings having only 100% or 0%, regardless of what your actual values were...

Johnny
08-08-2003, 03:55 PM
No, I'm using 7.5c

BTW, I re-checked my objects and all are set to be affected by the lights.

J

toby
08-08-2003, 04:24 PM
I'd say it's time to load one of those objects into a new scene and see what happens. If that still doesn't work, turn off all shaders. If that still doesn't work, post the objects and scene for us to check out - I'd love to see it!

Johnny
08-08-2003, 04:25 PM
ok..will do...

if it comes to posting, I can take a screenshot from above so that you can see where the objects, lights and camera are, relative to each other..

J

Johnny
08-11-2003, 07:55 PM
Here is an example of what I mean. The tall, cylindrical bottle with the cork and flanged top has a bumpy surface, and I can see why that surface might capture more light, but the bottles at either far right or far left look 'dead' to me with respect to light.

I selected Enhanced Extreme for this render, Caustics on.

the actual lights are - clockwise from the backlight at left: 40%, 40% 100%, 100%...all spots. There is a floor with reflection, and objects in the background are: a curved wall of glass with a bumpy texture, and a flat panel whose surface has that colored texture background you see.

Getting ridiculous (1200%) with the light intensity doesn't really do much, except to give some hotspots, but somehow I'm losing light activity in this scene.

Turning off the shaders makes those bottles more visible in one sense, but they lose a lot of glass-like beauty, too.

any hints would be appreciated.

thanks!

Johnny
http://home.earthlink.net/~zoomin/glas.jpg

Johnny
08-11-2003, 08:17 PM
with respect to that scene, I wonder whether I have enough elements IN the scene for the glass bottles to reflect, and therefore help show their dimension and light-catching abilities?

there's nothing overhead, or in front (in the direction from the bottles to camera); only the floor, and the background.

J

mlinde
08-11-2003, 09:20 PM
I'd try two things here.

1) Load a reflection map image to the surfaces for your "enough to reflect" worries.

2) Utilize the "Exclude" option to turn off some of the spotlights for some of the objects, to cut down on light splash, and see if that works.

Avebeno
08-12-2003, 01:08 AM
Treat glass like a mirror... You'll get better results if you look at the reflections you are getting in the glass.

A single light will look like a small shiny spot in the glass so try a different approach. Look at a real glass and you'll see the world reflected in it.


I like to use a sphere as a bight object that I can move around to control where reflections come from.

If your glass has liquid in it you might place a bright object behind your glass
but make it invisible to the camera.

toby
08-12-2003, 01:46 AM
Your going to have to post those objects so we can load them and check them out. Are you sure the sufaces are identical (they're different colors I notice) ? shaders - double/single sided - all that? It looks like you have Fast Fresnel on the one bottle and not the others.

It looks to me that either the surfaces are different, lights are excluded, Unseen by rays, or something is wrong with Layout. Did you try an new empty scene with a bottle that works and one that doesn't?

edit
oh yea, what about the "bumpy surface"? did you put it on the other bottles?

Johnny
08-12-2003, 06:51 AM
Originally posted by toby
edit
oh yea, what about the "bumpy surface"? did you put it on the other bottles?

your guesses are spot-on! all have some combination of fast and real fresnel with thin film. some have bumpy surface, the bulb-shaped bottle has something more 'wavy'

Link to the scene and files below. Thanks for taking time to look at this!

J
http://home.earthlink.net/~zoomin/glas.sit

toby
08-12-2003, 02:34 PM
the biggest difference I see so far is that the bottle that stands out is using Fast Fresnel while the ones that are 'dead' have Real Fresnel on them, which is a much more subtle shader.