Computer Graphics and CAD
Introduction
Computer graphics is a mature discipline which is concerned with the
representation, transformation, and display of objects. In solid modeling
system complex an object can be represented by its boundary (known as B-rep)
or by constructive solid geometry ( or CSG in short). These two representation
schemes are usually used together. Displays of objects can be either linedrawings
or photo-realistic shaded images depending on specific applications, hidden
lines or hidden surfaces are needed to be removed respectively.
Computer graphics techniques can be used in Computer Aided Design in
architecture, mechanical parts, ship, car, airplane design. It also facilitates
Finite Element Analysis and Calculation.
Projects
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“Five-Year Plan” Key Project of China: Computer Aided Design
System for Instrument and Meter Design, funded by the Ministry of Mechanism
of China.
Designing instrument and meters has increasing demands from industry.
The project is aimed to provide a powerful and ease-to-use CAD system to
enhance both and quality and productivity of such design task. It is also
required that the data generated in design phase can be directly used in
CAM.
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Model-based vision, funded by NSF of China.
The project consists of two parts. One is model-base generation, the
other is identification of model in real images. We construct complex object
using simple primitives such as block, cone, cylinder, and sphere, and
so on. Through set operations such union, intersection, and subtraction,
we can build up most man-made objects. Then, we construct aspect graphs
for each model which is later used for recognition.
Computer Aided Instrument Modeling
System
Like other modeling system, our system contain most the common functionality
such model creation, manipulation, rendering, storing and loading, and
so on. The objects in this system are described by polygons and NURBS patches.
Considering that instrument is usually composed of a number of standard
parts, we construct a standard component library to prevent user from constructing
imaginary objects from primitives. Since the outlook of instrument
is one of key issues, we build up a material library besides providing
a powerful renderer. The system also has an instrument decomposition module
that is designed for disassembling it into manufacturable parts. The system
can be used for other purpose, e.g., architecture design, machinery design.
The system was written in Fortran 77 with Plot 10 as the graphics package.
It runs on VMS/VAX with Tektronics 4129 graphics terminal.