line string or poly boundary is self-intersecting

ITopologicalOperator2=topoOp=feature.Shape as ITopologicalOpearator2;//此次为feature.Shape，不知道为什么，提前对Polygon做Simplify()会无效.

topoOp.IsKnownSimple2=false;//false才能是下面的simplify运行

topoOp.simplify();//和Ipolygon借口的SimplifyPreserveFromto()一样的效果。