Elsa Erazor II User Manual

– Bump mapping introduces a new dimension.  Relief or raised textures can only

be generated with the other methods in two dimensions using light and shadow
effects.  In bump mapping, the texture is additionally assigned height informa-
tion, which allows very realistic three-dimensional effects to be created.  

The staircase effect is corrected by anti-aliasing.  This is either done by interpolating
mixed pixels, in which a new color value is computed from two adjacent color val-
ues, or by using transparent pixels of the same color which are overlaid over adja-
cent pixels.

쮿

Shading – Shading takes account of the effects created by different light sources
on the 3D object and provide for a very realistic overall impression.  Here, too, there
are different methods which are more or less processor-intensive:

– Flat shading assigns a color value to each polygon.  This results in a mosaic-like,

jagged representation, which demands only a short processing time.

– In Gouraud shading, all the vertices of the polygons are assigned a color value.

The remaining pixel information for the polygon is interpolated.  This method
gives a very gentle color transition, even with fewer polygons than are required
for flat shading.

– The Phong shading method additionally takes a normal vector of reflectivity into

consideration when interpolating.  An even more realistic impression is gener-
ated by the representation of reflections and mirror images.

– Certain applications use ray tracing methods.  This is a very computer-intensive

and time-consuming process in which each individual pixel and its reflection in
3D space is calculated.

쮿

쮿쮿

쮿

The finished image will not be written to the frame buffer until this complex
sequence of steps is completed.  The frame buffer is made up of front and back
buffer.  The back buffer acts as a buffer page, in which the next image to be dis-
played is built up.  This prevents the process of image drawing being visible.  The
duplicate storage method is also known as double buffering.

The content of the front buffer is displayed on the monitor.  When the drawing process
in the back buffer is completed, this image is then passed to the front buffer in a process
known as flipping.

The next image will only ever be displayed once the image drawing process in the back
buffer is completed.  This procedure should be repeated at least 20 times a second to give
a smooth representation of 3D scenarios.  In this context, we speak of frames per second
(fps), a very important value for 3D applications.  A cinema film runs at 24 fps.