Matrix Circles Method for Complex Filled Patterns

Commercial CAD systems in general offer the simple filled patterns．This paper uses the idea of matrix circles model which regards the circle as a polygon （ at least dodecagon） ，and connect the polygon edges in different ways to make up the desired filled pattern．Atext file format is designed to describe the filled pattern．Adatabase consisting of more than 200symbolic patterns has been implemented to meet the needs of petroleum geology plot．