摘自上一篇相关代码
IEnvelope pNewEnv = new EnvelopeClass();
pEle.QueryBounds(pAv.ScreenDisplay, pNewEnv); ISegmentCollection segCol = new PolygonClass(); segCol.SetRectangle(pNewEnv);
由IElement对象获取IEnvelope,由IEnvelope获取IGeometry
原文：http://www.cnblogs.com/DayDreamEveryWhere/p/4311945.html