PDA

View Full Version : Lighting Question



The_Gravedigger
04-06-2004, 12:20 PM
Ok I'm trying to get a certain effect with my lighting. Sofar my scene has a large cave with a big hole in the floor. I want light to be coming out of the hole.

I have lighted it so that it gives it that "there-is-something-bright-at-the-bottom-of-this-hole" look but I want rays of light to be coming up out of the hole.

I'm not sure what effect will do this. I have tried putting a very bright spotlight down the hole and pointing it upwards but it doesn't give it that "ray of light" effect.

Anyone know what I need to do?

hrgiger
04-06-2004, 01:09 PM
Yes, turn on volumetrics in the light properties panel. Check out the last page of my thread here. Is that the effect you're after?

http://vbulletin.newtek.com/showthread.php?s=&threadid=19227&perpage=15&pagenumber=7

The_Gravedigger
04-06-2004, 02:32 PM
Yes thats exactly what I'm looking for. Do i just turn volumetrics on or do i have to do anything in the options as well?


Right now I am using a point light and I want the light to be red. Not sure if any of that makes a difference.

hrgiger
04-06-2004, 03:21 PM
You don't HAVE to mess with any of the options, it just depends on your scene. You might have to adjust the size of the volumetric effect. If the light is red, you may try upping the redshift value in the volumetric panel instead of turning your light red just to see what it looks like first.

The_Gravedigger
04-06-2004, 03:24 PM
Volumetrics dont seem to be doing anything. I have the point light quite a ways down the hole and I have the intensity at like 200% or more.

I turn volumetrics on it doesn't do anything. I will try turning the light back to white and upping the red shift like you said.

The_Gravedigger
04-06-2004, 04:27 PM
Well i turned the red shift up and nothing. I messed with some of the volumetric options so maybe I messed something up. Can someone give me an example of the settings I should have to produce the effects I want. And also do I need to use a spot light instead of a point light or does it matter?

hrgiger
04-06-2004, 04:57 PM
Try increasing the size of the volumetric effect. Also, try pulling the light out of the hole and render it to make sure the effect is working. My guess is, the volumetric effect is ending before it leaves the hole.

The_Gravedigger
04-06-2004, 05:08 PM
heres what it looks like when I bring the light all the way up to the surface...

am I supposed to have volumetric radiosity on? I would try it but it will take a long time to render.

The_Gravedigger
04-06-2004, 05:29 PM
heres what my volumetric options are.....

The_Gravedigger
04-06-2004, 05:30 PM
and heres how my lights are positioned

Bushmsn
04-06-2004, 07:18 PM
move your light up and also mess with the cone base and hieght this effects the lenght of the rays you also want to use the dissolve so the light does not over light the scene.

The_Gravedigger
04-06-2004, 08:01 PM
Its still giving me an effect similar to the red one above. Its a spotlight but the render is making it show up like a point light. I have been at this for hours and its getting frustrating.

I have tried moving around the height and the cone angle but that just makes the ball of light brighter or dimmer orr larger or smaller.

Why does it look like a ball of light instead of a ray of light like it should?

hrgiger
04-06-2004, 08:44 PM
It doesnt' look like you have volumetric lights enabled. I don't see the guide on your light.

If you did, you should be able to see a volume guide. Look at my pic below. That big cone that is stretching away from the light is showing where your volumetric lighting will appear. The render is shown below. You should have the checkbox checed where it says volumetric lighting. You don't need radiosity. For your scene, you should just postion your light so it isn't obstructed by an object, turn on volumetric lighting and turn on raytrace shadows (although you can also use shadow maps with the spotlights).

If you're still having trouble and would like to send me the scene/object, I'll fix it for you.

hrgiger
04-06-2004, 08:46 PM
Actually, I can see what's wrong now looking back at your picture. Your volume cone doesn't come anywhere near reaching out of the hole, you left it at 10 m. See that tiny little cone off your light? You need to increase that 10 m until that cone sticks up out of the hole.

The_Gravedigger
04-06-2004, 08:56 PM
I did. I streteched the cone way up out of the hole and it looks nothing like how yours does.

The red is a point light a have further down. I have the spot light set to white at the moment

The_Gravedigger
04-06-2004, 09:08 PM
..

hrgiger
04-06-2004, 09:12 PM
Here, I did a quick mock up of your scene.

The_Gravedigger
04-06-2004, 09:21 PM
thats the effect I'm going for. I have tried everythign you guys have said but it still coming out wrong. There must be some setting I have wrong to cause this

hrgiger
04-06-2004, 09:23 PM
I can email you this scene and object if you want to take a look at it.?

The_Gravedigger
04-06-2004, 09:23 PM
ok

my email adress is [email protected]

hrgiger
04-06-2004, 09:26 PM
Just sent them to you. Let me know if you have any questions at all. I hope this is helpful to you.

The_Gravedigger
04-06-2004, 11:53 PM
thank you very much. I still dont know what I was doing wrong but by copying your lights i managed to get it how I wanted.

colkai
04-07-2004, 06:29 AM
Not to sound funny but, just copying HRGigers lights isn't the answer.
For him to have really helped you, you need to look at the differences bewteen your original scene and his light setup. Note what was different and where and play with those settings.
Get an idea of the reuslt of this, then he has helped you not for just this one example, but in any future efforts as well.

Or you could just get him to do the next scene :p

Remember, give a man a fish and you feed him for a day, show him how to fish and he'll spend the rest of his life on a riverbank. (Or summat like that! :D )

Bushmsn
04-07-2004, 10:47 AM
can you post the scene?

jamesl
04-07-2004, 10:57 AM
hey hrgiger, that looks like hell. :p

j

hrgiger
04-07-2004, 02:17 PM
Bushmsn,

I deleted it after I sent it to The_Gravedigger.
The scene is simple though and only took me about 5 minutes to setup. All I did was model a flat plane, extruded a hole and applied a small amount of jitter for uneven ground.
In Layout, I applied a cracked ground texture from the preset panel, stuck a bright red pointlight in the hole and turned it up to around 300%. Then stuck a spotlight down the hole pointing up. Turn on volumetrics for the spotlight. Made both lights the red color and rendered.

And thanks James.