Research On The Method Of Parametric Design Of Resources Map In Resources Information System

In the field of computer-aided design of land and resource maps, engineers always want to get a kind of freer condition. The system functions are changed from mere computer-aided map drawing to real computer-aided map design, and can represent designer's ideas sufficiently and the modeling and processing of graphs and maps are being led to be intelligentized and roboticized. In this paper a new technology and method of parametric design was introduced. The research and discussion of this approach are evolved to the characteristics of resources map design.Although current CAD technology is used very widely, traditional environment of resources map computer-aided design still has some disadvantages clearly which mainly are: (l)the flexibility of map model is not good; (2)cannot support the whole process of design scheme; (3) cannot support rapid design modification and effectively reuse of former design result; (4) cannot support consistency maintenance of designs; (5)cannot accord with the habit of engineering designers. Traditional CAD system was oriented to idiographic geometric shapes and engineering designers were over limited to some design details. But usually the designers firstly define a structure sketch as a design prototype and then get a best design result step by step through continually redefinition and modification of the prototype.To sum up, these problems are mainly occurred in the aspects of model building and operating environment of resources map design, and up to now are not solved. For example, the map model can not be used and changed because the application users are changed; the following graph modification is very fussy and the printed result can not keep the standard of patterns and line types. In order to solve these problems, the theory and method of parametric design was proposed in this paper and the researcher tries to get a new solution.Parametric Design is a burgeoning CAD technology which was developed in 1990s. So-called Parametric Design is defined as that the dimension value and topologic relations of geometric graphics (or volume elements) are defined by a set of parameters, and are controlled by the designers to build geometric models and shapes.Thereinto, the parameters and controlled dimensions of design objects have a distinctly correspondence relation and the modification of design result is driven by dimension. Its main technical features are: (1)a design method based on constraints. Constraint is a important basic conception in parametric design and it regulates relations among the entity elements through a number of rules and restricted conditions. Constraints can be sorted into geometric constraints and geometric topologic constraints, etc. (2)dimension driven based on entity data association. When a dimension parameter is needed to be modified confirmed by constraint reasoning, system will search the data structure corresponding to the dimension parameter and find correlate equations to calculate parameters and then drive the interrelated geometric graphics to change their shapes. It is easy to understand the meaning of dimension driven through its behavior...