3D Surface Properties
The geometry is only the starting point for a realistic image: in addition
you need to have realistic surfaces. VRML lets you control the following
Here is a set of sphere objects that have
various surface properties applied to them.
- Diffuse color: this is the color of the object under non-directional
- Specular color: this is the color the object reflects when light
shines on it.
- Shinnines: this is how much light it reflects. If it is both very
shiny and the specular color is bright, you see a starlight pattern
where it reflects.
- Emissive color: "the light from within". This is the color created
by an internal light source, such as from a lamp shade or light bulb
when the power is on.
- Transparency: this is a value between 0 (opaque) and 1 (invisible)
which controls how much light goes thru an object.
- Textures: you can take any .gif file and drape it over any figure,
no matter what its geometry. You can also control how that image
is applied in terms of scaling, rotation, and centering.
- Gourad shading in which the surface normals are smoothly interpolated
across vertexes so as to give a smoother appearance
If you have
Cosmo Player 2.1 installed you can manipulate
this scene in 3D
Non-VRML graphics systems often have far more capabilities. They include
such things as:
- Bump maps which change the surface normals so that as light moves over
you see bumps and valleys
- Transparency maps whereby you create complex holes in objects
(or windows with degrees of transparency)
- Gel maps which map textures of light sources onto objects, such as
the window pane pattern which comes from light thru a window
- Phong shading which interpolates a large set of surface normals
in such a way as to take fully into account the textures and
other properties of a surface.
In addition, non-VRML systems use maps to control other properties on a
pixel level, whereas in VRML they are applied to the entire object. Thus
a diffuse color map might specify the diffuse color and intensity for
every pixel, whereas in VRML the diffuse color is applied as a single value
to the entire object. This applies to other properties as well, such
as specular color, specular intensity, transparency, shininess, etc.
This mapping greatly increases the realism.
Also, texture maps can often be applied in more ways, such as
different types of projections (planar, cylinderical, spherical),
different tiling patterns, different degrees of coverage, etc.