diff --git a/lib/geometry/point3s.h b/lib/geometry/point3s.h
index 9e4e5c8..9b60050 100644
--- a/lib/geometry/point3s.h
+++ b/lib/geometry/point3s.h
@@ -471,32 +471,45 @@ namespace gctl
 	 * @param[in]  dlon    lon间隔
 	 * @param[in]  dlat    lat间隔
 	 * @param[in]  rad     半径值
+	 * @param[in]  cor     网格起始位置
 	 */
 	template <typename T>
-	void get_grid_point3s(array<point3s<T>> &out_ps, T lonmin, T lonmax, T latmin, 
-		T latmax, T dlon, T dlat, T rad)
+	void grid_points_2d(array<point3s<T>> &out_ps, T lonmin, T lonmax, T latmin, 
+		T latmax, T dlon, T dlat, T rad, matrix_corner_e cor = BtmLeft)
 	{
-		if (lonmin >= lonmax || latmin >= latmax || lonmin+dlon>lonmax || latmin+dlat>latmax)
+		if (lonmin >= lonmax || latmin >= latmax || 
+			lonmin + dlon > lonmax || latmin + dlat > latmax || 
+			dlon <= 0 || dlat <= 0)
 		{
-			throw invalid_argument("Invalid range parameters. From get_grid_point3s(...)");
+			throw invalid_argument("[gctl::grid_points_2d] Invalid parameters.");
 		}
 
-		if (dlon <= 0 || dlat <= 0)
-		{
-			throw invalid_argument("Invalid interval parameters. From get_grid_point3s(...)");
-		}
-
-		int lonnum = floor((lonmax-lonmin)/dlon) + 1;
-		int latnum = floor((latmax-latmin)/dlat) + 1;
+		int lonnum = round((lonmax-lonmin)/dlon) + 1;
+		int latnum = round((latmax-latmin)/dlat) + 1;
 
 		out_ps.resize(lonnum*latnum);
-		for (int j = 0; j < latnum; j++)
+		if (cor == BtmLeft)
 		{
-			for (int i = 0; i < lonnum; i++)
+			for (int j = 0; j < latnum; j++)
 			{
-				out_ps.at(j*lonnum+i).lon = lonmin + dlon*i;
-				out_ps.at(j*lonnum+i).lat = latmin + dlat*j;
-				out_ps.at(j*lonnum+i).rad = rad;
+				for (int i = 0; i < lonnum; i++)
+				{
+					out_ps.at(j*lonnum+i).lon = lonmin + dlon*i;
+					out_ps.at(j*lonnum+i).lat = latmin + dlat*j;
+					out_ps.at(j*lonnum+i).rad = rad;
+				}
+			}
+		}
+		else // cor == TopLeft
+		{
+			for (int j = 0; j < latnum; j++)
+			{
+				for (int i = 0; i < lonnum; i++)
+				{
+					out_ps.at(j*lonnum+i).lon = lonmin + dlon*i;
+					out_ps.at(j*lonnum+i).lat = latmax - dlat*j;
+					out_ps.at(j*lonnum+i).rad = rad;
+				}
 			}
 		}
 		return;