The Research and Implementation of Illumination Technology in the 3D GIS Visualization

Building mountains as the basic model for illumination model in the system of 3DGIS visualization. The establishing of this model adopts the approach of the global illumination model combine with the local reflection model and also the combination of shading and shadow. Complete the drawing of the shadow in the global illumination model,using the shadow algorithm of Ray tracing as the main algorithm for drawing shadow, take advantage of shadow volume algorithm as the additional algorithm for shadow; complete the drawing of the shading in the local reflection model,using the Blinn proportion algorithm as the main algorithm. Select the single ideal fixed point source as the light source of the illumination model. The results of this experimental show that the approach of combination of global and local model is feasible, the selection of the shadow and shading algorithms are also can reference.