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Daylight tutorial by Carles Piles - page 2
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5. LIGHTING
This stage of the work is the most time-consuming of the entire scene, because I had to do a lot of testing of the effects as I went along.
The main light sources are the "Sun", the "Bouncing" light from Sun/sky and
the "Skylight".
The "Sun" is a hard, yellow shaded parallel light. "Bouncing" is the result mainly of sunlight bouncing on the geometry but "skylight" also produces bouncing light at all directions. "Skylight" is blue light surrounding the entire scene.
All lights are added gradually. Note that between lighting stages, the increment of change is small.
Using a big number of low lights gives better results than using a few lights with high values. The idea is to create something like a "lighting
grid" to fill the dark areas using colours
Simulating light sources using spots and omni lights-
THE SUN:
I used a spot placed far enough away to cover the entire scene. Light colour is warm yellow using a value of 270%, with area shadows enabled. Area shadows are more accurate than other shadows. Area shadows will show hard or soft shadows depending on the object's distance, like real shadows. This takes more render time than other shadows, but looks nice.
Using soft shadows with a big map size, "sun" shadows looks nice too, and
while this will save time, the area shadows really are better.
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6. MAIN BOUNCING
To simulate the first bouncing light from sun, I used two lines of blue omni lights (8 lights each line) placed along the "street". They are instances from a "master blue light". It's easy to adjust because you need only adjust the Master to have the change propagated to the 'cloned' lights.
The first 'light-string" is placed near the floor and second "light-string" about the middle of the maximum height of the scene. These strings of lights fill all areas softly with a uniform lighting. (Using more lights with a lower value results are nice but that takes more render time and tests.)
At this point, the top area still is too dark, but we can solve this later using only a few lights.
The Master blue light (and consequently all 16 instances) uses a 10% value, the colour is blue and soft shadow is enabled (125 kb size map); this produces soft-shadows and lighting, which emulating a radiosity effect, but isn't as render intensive.
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7. SKY
For the main skylight I used three instances from a couple of blue spotlights targeting the walls and the floor for a total of 8 lights along
the scene. The parameters used are: blue colour, soft shadows (sample size to 6 to create a more diffuse shadow) and a 20% value. -This produces more "filled scene" and visible shadows under the Bridge, on floors, and walls.
At this point, some areas are still too dark, so we need to fill them with light.
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8. Lighting the scene using "bounce lights" and overhead "skylights"
The front view of our bridge looks unnaturally dark, and not in harmony with the walls because there aren't skylights targeting it yet (At this point, we 've only got "skylights" on right/left sides.) This time, a simple spot is placed at a distance to fill all frontal areas. To take more control of lighting exposure, I used a lineal falloff and soft shadows using opacity only at 50%; this produced a more "filling" light.
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Note that the bottom area of our bridge doesn't show enough bounced-light while sunlight looks high on the floor. To remedy this, a simple light without shadows is placed under the scene to fill bottom areas with "reflected" light. This simple light uses a 15% value.
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Now is when I apply the overhead "Skylight":
In total three omni lights with falloff are placed in a medium-top area of the overall scene. Two omni lights with a 20% value are placed at front and back of the bridge, at a medium-top position. The third light, with a 35% value, is placed at the top, higher up, but toward the front since only this area is visible to the camera.
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9. Finally small details to improve believability
Because the walls at the back of the bridge fade to open space, more Skylight must appear on it. To "overexpose" the open area I used a pair of blue spots with a 30% value, targeting the walls at top, and an omni yellow at 25% value with falloff on the open space between the end and rear wall.
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THE IMAGE IS FINISHED -
Rendering time:
5 minutes: 42 seconds (600x600 píxels) on a Pentium4 1.5GHz/650RAM.
Carles Piles 2002.
URL: www.3dluvr.com/carles
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