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How to position lights with Outer Space Background
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February 07, 2011, 01:16:01 PM
I am using the IMSI-provided outer space.jpg as the background in Render Scene Environment. How can I position my lights so that the shadows appear as if they were generated by the light source in the background image?
Thanks,
Milt

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* February 07, 2011, 03:45:59 PM
#1
Consider placing a single "Directional" light to cast the shadows. Add a single Headlight and a single "Ambient" light, too. Expect to adjust the location of the Directional light and its target, and the properties of all three lights, to make the rendering look right.

EDIT: On second thought, a "Point" light might be better than a "Directional" light. The second attachment uses a Point light.

Henry H
« Last Edit: February 07, 2011, 06:40:25 PM by Henry Hubich »

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February 07, 2011, 07:46:25 PM
#2
a "Point" light might be better than a "Directional" light

Why, Henry? I think your first image looks better - the parallel shadows give a sense of distance and work well for that particular scene.

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Julian

TC18 / 38.5 Platinum, AL5. XP, Core2 Duo E6750 OC'd 3.0Ghz, Render test: 3mins 3sec.


* February 07, 2011, 07:59:41 PM
#3
a "Point" light might be better than a "Directional" light

Why, Henry? I think your first image looks better - the parallel shadows give a sense of distance and work well for that particular scene.

I take your point, Julian; in fact, that's what I first thought. However, shouldn't a distant concentrated light source, an object, and the shadow of that object lie on a straight line? In the first image, the shadow of the sphere does not lie on a line which extends from the light source through the sphere.

Henry H

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February 07, 2011, 09:28:49 PM
#4
shouldn't a distant concentrated light source, an object, and the shadow of that object lie on a straight line?

Of course, but who's gonna calculate the shadows' included angle? Maybe a point light 93 million miles away would sort it?

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Julian

TC18 / 38.5 Platinum, AL5. XP, Core2 Duo E6750 OC'd 3.0Ghz, Render test: 3mins 3sec.


February 08, 2011, 03:08:02 PM
#5
My original question should have been "where" instead of "how."

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February 08, 2011, 05:33:15 PM
#6
My original question should have been "where" instead of "how."

Hi Milt,

Are you using that bright star in the background image as the light source or something else within the drawing?


February 08, 2011, 06:24:16 PM
#7
My original question should have been "where" instead of "how."

If you are using the star as the light source, I would suggest setting up your final view first and save it. Remember that the background image is always in the same place.

Once established, create a polyline out and up from your object to be lit. (see screen066)

Go back to your view and rotate the polyline to line up with the star (reference point was changed to center of object. (see screen067)

Snap directional light from high far point to something on the object to be lit. (see screen068)

Return to saved view and render. (see screen069)


February 13, 2011, 02:51:19 PM
#8
Thanks for all the comments and especially Don's illustrations. I haven't got it solved yet, but I now know what I need to do.

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