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Old 25-01-2004, 01:43 AM   #1
Brian820
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Default Light shining through polygon, help please

Hello everyone, and thanks for taking the time to view my question. My name is Brian, and this is my first post here at SimplyMaya.

I'm a self-taught Maya user just beginning my first project that didn't come with a walkthrough and I'm having a basic lighting problem that I hope someone can help me with.

I've modeled a spaceship from an extruded/tweaked polygon, leaving a two cavities in the back for thrusters. I want to place a light (probably spot or point) inside each cavity to light up the thruster space as well as shine some light out the back. The problem is, my lights are shining THROUGH various parts of the ship. For example, if I place a point light in the middle of the left cavity, it shines bright enough to illuminate the right cavity, the interior of the spaceship, and even highlights parts of the wings.

I did a little test by placing a sphere above the spaceship, and that sphere is picking up that light even though it should be entirely in shadow. Let me illustrate with a very crude diagram.


|...sphere..........O
|................._______
|................/........__|
|....ship.....<......C*__...light in thruster cavity
|................\_______|


I cannot understand why that sphere would pick up lighting from a light separated by two faces and some polygon area.

My guesses are, something is wrong with my light, or something is wrong with the texture/material of my ship.
Reducing the light intensity does help the problem, but this doesn't seem like the correct solution as NO light should penetrate the ship's surface anyway.
The texture on my polygon I believe is entirely opaque, with no transparency or translucency.

So, what settings/changes should I do so that the light will only illuminate the cavity/cavity openeing and not penetrate through my model?

Thank you so much for taking the time to read this, and I would greatly appreciate any and all help.

-Brian

Last edited by Brian820 : 25-01-2004 at 01:49 AM.
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Old 25-01-2004, 02:57 AM   #2
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Does the light cast shadows? Turn on shadows in the light's attributes.

Is it an ambient light? Ambient lights shine light EVERYWHERE, even on the opposite sides of objects.
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Old 25-01-2004, 03:54 AM   #3
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Default Point Light, Shadows on

Hi Mike, thanks.

I'm using a point light currently, and I've tried using Depth Map Shadows, Raytracing Shadows, and Shadow Maps all with no change in the image. The light is still shining through the ship to illuminate objects it shouldn't be able to reach.

Let me know if I should post a jpg or any other info that might help.

-Brian
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Old 25-01-2004, 05:07 AM   #4
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Try with the spot lights casting shadow. Sorry if you have tryed this and still having problems. I think the shadows will work better for you with a spot.

it is also posible that youhave recives shadows terned off on the ship geo.
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Old 25-01-2004, 05:20 AM   #5
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It's possible that you may need to reverse the ship's normals, or, if you're planning on rendering from outside the ship, give the ship some thickness so normals are facing both directions.
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Old 25-01-2004, 10:28 AM   #6
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Those both sound like good ideas...I'm just not sure exactly where to check.

1) How do I ensure that my material is capable of receiving shadows?
2) How do I add thickness to my faces...and will that help?

Another dimension to the problem, is I have a ton of light penetrating to the interior of the ship and bouncing around in there, causing further problems.

I'm getting the impression that the light is illuminating one side of the face, yet somehow both sides are being lit and the opposite side is transmitting light through. Does this help anyone come up with any ideas?

I've checked the normals and they all point outwards...towards the light.

-Brian
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Old 25-01-2004, 11:55 AM   #7
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A
1) its in the attribute editor. Highlight the object, and bring up the attribute editor for it. Say you have the object named polysurface9, click on the polysurface9shap tab. Expand the render stats dropdown, and receives shadows is down that list.

It might help if we can see a pic of the rendering.
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Old 25-01-2004, 03:56 PM   #8
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If you're using raytrace shadows, make sure you have raytracing turned on in your render globals.
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