Efficiency Analysis Of Distortion Visualization Algorithms For 3D Coherent Set

In the present cadastral administration system,numerous 3D building property objects are adjacent as main units that constitute a 3D coherent set.During visualization process of the coherent set,the present methods have difficult in presenting spatial position,architectural morphology of single unit as well as spatial relationships among the units of the coherent set.This research proposed three distortion visualization methods based on “focus + context” visualization concept,furthermore,3D coherent set generated from real estate data are used as experimental materials to explore the influence of different distortion algorithms on the cognition of three-dimensional real estate by the spatial cognitive experiment.We found that different algorithms have notably difference from the aspects of recognition about spatial forms,spatial location and spatial relationships.The main research results of this study are as follows:(1)Based on the analysis of eye movement data,it is found that the distortion visualization algorithms designed based on the "focus + context" cognitive theory can effectively provide guidance for the subjects in the visualization process,highlight the focus objects and extrude the focus.At the same time,it can help the participants pay attention to the information of the background objects and assist the cognitive understanding of the focus objects;(2)The background objects are shifted and shrunk in linear distortion algorithm,which can better help the users to recognize the spatial form of the focus object,but it cannot help to understand the spatial location and spatial relationship of the coherent objects for the reason of large extend distortion;(3)In the orthogonal algorithms distorted coherent set,the background objects are distributed in groups,so this distortion method has an advantage in helping the subjects to understand spatial position information of the focus object,guiding the subject to recognize the spatial relationship and spatial arrangement characteristics of the 3D distortion results;(4)As for discretized state visualization,each object has a positional shift,which leads to the lowest accuracy and the longest time in the spatial cognitive test about focal object's appearance and distribution of whole coherent objects.