1. College of Marine,Northwestern Polytechnic University,Xian,Shaanxi 710072,China;
2. School of Science,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China
Abstract：The paper proposes a new algorithm to trace isograms with fault constraints.It also develops a correspondingly coloring scheme to infill areas.The algorithm may be applied to study areas of various shapes regardless of their interpolation gridding types or the detailed classification of the contours.The paper assumes that all faults are polygons within the study area,so the faults and the study area enclose a multiply connected domain.It is an algorithm designed to trace equivalent areas based on the multiply connected topologic deformational areas.Firstly,regional topologic deformation is performed,as the study area is silted from a node on its outer boundary.Secondly,the outer boundary is drawn into a level line segment,which regulates all the areas of isograms above it.Finally,on the topologic deformational area,we get all the areas of isograms from top to bottom as well as from outside to inside.Meanwhile the paper discusses variation law of the attribute value inside the areas of contours.It also proposes a scheme to determine the infilling color by double monitoring point.The application on a real dataset validates the correctness and precision of the proposed method.The algorithm is also applied to commercial software which has been proved to be very efficient.
