通过传入坐标点，返回几何图形，此代码部分可以生成环形面。 

方法一

private IGeometry getGeometry(IPointCollection Points)        {            IPointCollection iPointCollection = new PolygonClass();            Ring ring = new RingClass();            object missing = Type.Missing;            ring.AddPointCollection(Points);            IGeometryCollection pointPolygon = new PolygonClass();            pointPolygon.AddGeometry(ring as IGeometry, ref missing, ref missing);            IPolygon polyGonGeo = pointPolygon as IPolygon;            //polyGonGeo.Close();            polyGonGeo.SimplifyPreserveFromTo();            return polyGonGeo as IGeometry;        }

方法二：

private IGeometry getGeometry1(IPointCollection Points)        {            //IPointCollection iPointCollection = new PolygonClass();            object pMissing = Type.Missing;             //iPointCollection.AddPointCollection(Points);            IGeometryCollection pGeoColl = Points as IGeometryCollection;            ISegmentCollection pRing = new RingClass();            pRing.AddSegmentCollection(pGeoColl as ISegmentCollection);            object miss = Type.Missing;            IGeometryCollection pPolygon = new PolygonClass();            pPolygon.AddGeometry(pRing as IGeometry, ref miss, ref miss);            ITopologicalOperator topologicalOperator = pPolygon as ITopologicalOperator;            topologicalOperator.Simplify();            return pPolygon as IGeometry;        }