gis二次开发，设置图层高程基准，先要安arcgis哦。c#写的，有用得着的可以-Gis second development, set up the layer vertical datums, first to Ann arcgis oh. C# written, a useful can see

包括部分空间算法，如计算两坐标点距离、判断两坐标点是否相等、计算叉积、计算点积、判断点p是否在线段l上、计算点bp以点op为圆心逆时针旋转dAlpha(单位：弧度)后所在的坐标点位置、计算指定半径圆上指定角度的弦长、计算由起点坐标和终点坐标构成的线段在指定距离和指定方向的垂点坐标等空间算法-Including some space algorithms, such as calculating the distance between the two coordinates to determi

A_very interesting paper, for civil engineers. It describes the behaviour of seismic isolated structures to vertical direction of an earthquake in seismic crack.