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我在 NTS(C#) 中使用 PrecisionModel 为几何中的坐标指定一个固定的小数位（即 0.1、0.01、0.001 ...）。

我为同一个 LineString 尝试了三个固定小数位：0.1、0.01、0.001。但是当我做一些联合操作时，0.1的精度总是会出错，而0.01和0.001的效果很好。

源代码如下：

//Obviously, the precision of the line and the point is is 0.1
var lineStr = "LINESTRING (1667.8 1368.6, 1741.1 4274.5, 1902.5 578, 1902.5 578.1, 1867.6 1377.3, 1667.8 1368.6)";
var ptStr = "POINT (1741.1 4274.5)";


//scale is 1000d, which means 0.001 precision
var f3 = new GeometryFactory(new PrecisionModel(1000d));
var wktReader3 = new WKTReader(f3);

//scale is 100d, which means 0.01
var f2 = new GeometryFactory(new PrecisionModel(100d));
var wktReader2 = new WKTReader(f2);

//scale is 10d, which means 0.1
var f1 = new GeometryFactory(new PrecisionModel(10d));
var wktReader1 = new WKTReader(f1);
        

//wkt strings to geometry objects
var line3 = wktReader3.Read(lineStr);
var pt3 = wktReader3.Read(ptStr);

var line2 = wktReader2.Read(lineStr);
var pt2 = wktReader2.Read(ptStr);

var line1 = wktReader1.Read(lineStr);
var pt1 = wktReader1.Read(ptStr);

var lines3 = line3.Union(pt3);
//result: MULTILINESTRING ((1667.8 1368.6, 1741.1 4274.5, 1869.307 1338.211), 
//(1869.307 1338.211, 1902.5 578, 1902.5 578.1, 1869.307 1338.211), 
//(1869.307 1338.211, 1867.6 1377.3, 1667.8 1368.6))

var lines2 = line2.Union(pt2);
//result: MULTILINESTRING ((1667.8 1368.6, 1741.1 4274.5, 1869.31 1338.21), 
//(1869.31 1338.21, 1902.5 578, 1902.5 578.1, 1869.31 1338.21), 
//(1869.31 1338.21, 1867.6 1377.3, 1667.8 1368.6))

var lines1 = line1.Union(pt1);
//result: NetTopologySuite.Geometries.TopologyException:
//“found non-noded intersection between LINESTRING(1741.1 4274.5, 1869.3 1338.2) 
//and LINESTRING(1867.6 1377.3, 1667.8 1368.6) [ (1867.59289230568, 1377.2996905058, NaN) ]”

很明显，初始lineStr的小数位是0.1，所以我觉得给PrecisionModel指定0.1就够了，真希望结果的精度也在0.1以内，不然就得做一些四舍五入的操作了。

使用 PrecisionModel 是否正确？谢谢你的帮助。

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