Lighting Effects (page 2)
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Robert Watson's Archangel(ess) was downloaded
also from anim8ortrade.
(Let's say frankly, she is better suited for a nudibar than for the heavens!)
We are going to cover her with a gloria. All that we need is glow effect
and rays, so let's add a glow filter and a ray device. If you aren't satisfied
with the glow, which is superposed over the face, move the glow filter
in the background. You may use a glow device in the foreground and one
in the background, tuning the effect as you wish! |
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Foreground and background
glow
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See on the left the set-up
of the scene. Use colors and animate the effect! |
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Adding a subtle jet glow to
the engines of Enterprise 1701A , found at anim8ortrade,
is just a piece-of-cake. We make use of volume light. Notice below the
attenuation of the jet and the stars seen through the glow. |
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The main problem with the
scene is related to the light used to make the engine glow. The starship
gained a bluish color that is not wanted, except the case that Enterprise
is passing in the proximity of an O, or B spectral class star. One of the
solutions is to shift the colors used for Enterprise in a direction opposed
to the light, in the RGB plane. (We used blue light, so we'll shift the
colors to yellow) I have also darkened the colors to emphasize the
self-illuminations. (See below) |
The scene is animatable (the
effect-responsible objects move along with the starship) without any change
in this setup (see below) as long as Enterprise doesn't change course. |
Click the image to enlarge
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This "spotlight" scene relies on the same
type of effect-maker object as the one for the jet-glow, a half-cone. The
variation is the use of a second light directed to highlight the rounded
end of the cone. You can adjust the intensity of the effect by changing
the material parameters of the effect-object.
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Moving a variable transparency filter in front of the camera, the level
of illumination can be varied up to total extinction. Notice the
use of a dark neutral filter for the background objects, placed behind
the effect-device, to darken the scene without fading the spotlight and
a second transparency filter (lighter) right in front of the camera, for
animating the light. |
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That easy is to simulate the falling of
the night.
Manufacturing the effect devices
Plane filters
Simple filled rectangles (2D objects) covering
the field of the camera. Depending on the material parameters assigned
to them, they are uniform filters, or texture projectors. Their effect
is visible at edit-time.
Neutral filter
Parameters: Color - a shade of
grey (R=G=B)
Transparency - a nonzero value
Us: Darkening the scene (dark grey
or black color), or creating fog in the foreground (light grey or white)
Colored filter
Parameters: Color
Transparency - a nonzero value
Ambient
Us: Changing the hue of the image.
A nonzero value for Ambient lights up the scene.
Variable transparency filter
It is a combination of neutral filters with
different values for transparency. We manufacture it starting from a box
with a number of divisions along one of the axes, than cutting half of
the vertices to make it a 2D
object. In point-edit mode select the faces one by one, assigning them
different material parameters (transparency, color)
Us: Sliding the filter in front of the
camera we can adjust dynamically the overall illumination (color and intensity)
of the scene during the animation.
Texture projector
Parameters: Texture - Any kind
of image, for example spots, a color gradient
Transparency - a nonzero value
Ambient
Us: Superposing a ghost image over
the scene. The sharpness of the image depends on the Transparency and Ambient
values and the distance between the camera and the filter (the farther
the filter, the sharper the image). It is a simple way for atmospheric
effects, like rain, snow falling (but not very realistic), better using
a rotating cylindrical filter.
It is useful to break the uniformity and unnatural clarity of the space
in 3D scenes. The spotted filter for the shark-scene uses a texture
painted with a soft airbrush tool with one-pixel spots on a uniform color
background. It makes a good job as plankton, but is visible discretely
only in high-resolution images.
Curved filters
Glow filter
Parameters: Shape - Mainly spherical
Transparency - Zero (completely transparent)
Specular
Roughness
The glow is a rendering
effect given by the specular highlight on the filter. A nonzero value for
the transparency is acceptable only if the filter covers the entire field
of the camera. The aspect of the glow is given by the parameters of the
filter (including the shape and smoothness of the filter mesh), the relative
position of the camera, filter and lights, and
the parameters of the lights. A smoother filter surface gives a more uniform
glow. The specular value controls the intensity, the roughness controls
the extension of the effect (a higher specular value increases the intensity,
a lower roughness increases the size of the glow). When positioning the
filter and the lights in the scene, we do it according to the simple low
of reflection. Everything is happening as in reality, the light from the
source hits the filter and reflects according to the normals of the surface.
At a proper positioning, a part of the reflected light reaches the camera.
Just a note: not the actual position of the light source is important,
but its direction!
As an example, the parameters of the hemispheric
glow filter used in the candle scene (for the outer glow)
Diameter - 30 units
Divisions: Long:12 Lat:8
Us: Simulating a light source,
a glowing object
Cylindrical filter
Parameters: Shape - Mainly cylindrical
Transparency - Zero (completely transparent)
Specular
Roughness
Us: Adding volume light to the
scene (as a rendering effect)
All the above notes for the glow filter
are applicable also to the cylindrical filter. For the shark-scene I used
a standard cylinder cut in half along its main axis, diameter 80 units,
length 130 units. The Enterprise jet-glow was made with a narrow-angle
cone cut in half, with the larger end bent. (See the image)
Ray devices
Ray-effect can be obtained at render-time
with an arrangement of cylindrical (conic) objects. The material parameters
are set to complete transparency and shininess, like for the glow filters.
For the candle scene I used a star made by four cylinders of one unit diameter.
The ray device for the
gloria is an extruded 24-Gon with all the faces peak-extruded (Peak Faces
tool). (See the image)
There is plenty of room for experimenting.
Take these notes as a starting point for your own "research". I had the
idea to use these effects recently and I'm in a rush to share it. If you
have already done lighting effects in Anim8or, tell me how.
Have fun,
Laszlo
Korosi
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