More information on this topic is also availiable from
Pat Angeles's project.
The Living Textbook
This project explores problems in creating a multimedia "flight simulator"
interface to a textbook. A child will be able to sit at a computer and
"fly" around the state of New York, learning about the geography, history,
ecology and demography of the area. Cities and other points of interest
will have hotspots leading to more information. Because it is geographically
referenced, this database format will encourage learning with each use.
Examples of data formats used are:
Elevation
Landsat
Digital Line Graph
Implementation
The textbook needs to able to run on many platforms, allowing a wide
availibility. A central high performance computer would render the
data and then send it to whatever hardware the schools possess. Smaller
modules would also be able to run on the school's own terminal.
This setup brings many concerns, two of which are:
- What is the best way to transfer the data from the main renderer to
the display computer?
- How much preprocessing can be done to the data to speed up the
rendering process?
Parallel Virtual Machine
An answer to the first question could have been PVM or Parallel Virtual
Machine. It is a widely avaible, easy to use, heterogeneous computing
environment, However, it did not provide the speed nor the stability
needed. Further exploration into increasing frame speed through
image compression also proved unfruitful. The best way to transfer the
image data still remains unsolved, though probably lies in less portable,
but faster protocols.
Shading and Shadow Preprocessing
However, as an answer to the second question, a significant portion of
the rendering process, the computation of shadows and shading can be done in a
preprocessing step. Because the light source remains constant and
mountains are virtually non-reflective, shading and cast shadows do
not change from one view to another. As a part of this project, I wrote
a program to compute the shading of each vertex of each polygon in the
terrain. This value can then be interpolated in the actual rendering process.
The shading program itself used Lambertian shading for the direct sunlight
and a Z-buffer algorithm to calculate the vertices in shadow.
The paper for this project is also available.
Stephanie Weirich email:sweirich@npac.syr.edu
Paul Coddington
email:paulc@npac.syr.edu
1994 NPAC REU program.
Elevation
Landsat
Digital Line Graph