前因：因做管线分布时，参照线选择Revit链接文件中的构件（墙，梁，柱，管等）后，调整的管距离参照线的距离不对，经测试是坐标系不同导致。查了很多资料，故总结如下
Revit中坐标系有哪几种（原文链接：/JoeXiongjin/article/details/8202910）
模型坐标系： 也理解为全局坐标系
视图坐标系：与模型坐标系之间的转换
族坐标系： 在制作族有一个坐标系，族插入到模型中，其中的几何体有自己在模型中的位置，需要进行模型坐标系的转换。
链接模型坐标系： 链接模型的位置在host模型中的位置，需要坐标转换。
如何进行坐标转换
使用Transform进行坐标转换，在叶雄进老师的博客中描述有三种获得Transform的方法，
1. 自己创建一个转换矩阵：
2. 直接从Revit的对象获得转换矩阵。
3. 从视图中获取视图到全局坐标系的坐标转换。
我只会用第二种（从Revit的对象获得转换矩阵），以下举两个自己遇到的两个例子用作说明
链接模型坐标系转模型坐标系(这段代码的目的是选取链接文件中的墙，然后得到链接文件中构件对象的trans，最后转换墙的curve的两点坐标，然后打印出来，打印出来的坐标就是模型坐标)
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using Autodesk.Revit.UI;using Autodesk.Revit.DB.Structure;using Autodesk.Revit.UI.Selection;using Autodesk.Revit.DB;using Autodesk.Revit.ApplicationServices;using Autodesk.Revit.Attributes;using Autodesk.Revit.DB.Mechanical;using Autodesk.Revit.DB.Electrical;using Autodesk.Revit.DB.Plumbing;namespace WindowTest{[Regeneration(RegenerationOption.Manual)][Transaction(TransactionMode.Manual)]public class Class1 : IExternalCommand{public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements){Document revitDoc = commandData.Application.ActiveUIDocument.Document; Application revitApp = commandData.Application.Application; UIDocument uiDoc = commandData.Application.ActiveUIDocument;Reference reference1 = uiDoc.Selection.PickObject(ObjectType.LinkedElement, new SelectionLinkFilter(revitDoc),"请选择一个链接参照构件");Transform trans = null;if (reference1 != null){// get RevitLinkInstanceElement ele2 = uiDoc.Document.GetElement(reference1);RevitLinkInstance linkInstance = ele2 as RevitLinkInstance;trans = linkInstance.GetTransform(); //get transDocument linkDoc = null;linkDoc = linkInstance.GetLinkDocument();Element wall = linkDoc.GetElement(reference1.LinkedElementId);Line line_test = (wall.Location as LocationCurve).Curve as Line;XYZ wallLineStartPoint = line_test.GetEndPoint(0);XYZ wallLineEndPoint = line_test.GetEndPoint(1);if (wall is Wall){TaskDialog.Show("wallStartPoint", wallLineStartPoint.ToString());TaskDialog.Show("wallEndPoint:", wallLineEndPoint.ToString());TaskDialog.Show("Trans_wallStartPoint", trans.OfPoint(wallLineStartPoint).ToString());TaskDialog.Show("Trans_wallEndPoint", trans.OfPoint(wallLineEndPoint).ToString());}else{TaskDialog.Show("ERROR", "请勿选择非墙的元素！");return Result.Failed;}}return Result.Succeeded;} }//外链接过滤器public class SelectionLinkFilter : ISelectionFilter{public RevitLinkInstance rvtIns;private readonly Document _doc;Document linkDoc = null;public SelectionLinkFilter(Document doc){_doc = doc;}public bool AllowElement(Element elem){if (elem is RevitLinkInstance){linkDoc = (elem as RevitLinkInstance).GetLinkDocument();rvtIns = elem as RevitLinkInstance;return true;}return false;}public bool AllowReference(Reference reference, XYZ position){//TaskDialog.Show("reference.LinkedElementId", linkDoc.GetElement(reference.LinkedElementId).GetType().ToString());if (linkDoc.GetElement(reference.LinkedElementId) is Wall){//TaskDialog.Show("RevitLinkInstance", (_doc.GetElement(reference) is RevitLinkInstance).ToString());return true;}return false;}}}
族坐标系转模型坐标系(这段代码的目的是选取柱子的一条边（备注：柱子是族实例），然后得到柱子的几何实例对象的Trans，最后对选取的柱子的这条边进行转换，最后得到的坐标就是模型坐标)
要想清楚知道族坐标和模型坐标之间的关系的，可以查看叶雄进老师的这篇文章 文章链接：/JoeXiongjin/article/details/16883451
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using Autodesk.Revit.UI;using Autodesk.Revit.DB.Structure;using Autodesk.Revit.UI.Selection;using Autodesk.Revit.DB;using Autodesk.Revit.ApplicationServices;using Autodesk.Revit.Attributes;using Autodesk.Revit.DB.Mechanical;using Autodesk.Revit.DB.Electrical;using Autodesk.Revit.DB.Plumbing;namespace WindowTest{[Regeneration(RegenerationOption.Manual)][Transaction(TransactionMode.Manual)]public class GetFamilyInstanceTrans : IExternalCommand{public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements){Application revitApp = commandData.Application.Application;UIDocument uiDoc = commandData.Application.ActiveUIDocument;Document revitDoc = commandData.Application.ActiveUIDocument.Document;Selection S2 = uiDoc.Selection;Reference re = null;try{re = S2.PickObject(ObjectType.Edge, "请选择柱的一条边：");}catch (Autodesk.Revit.Exceptions.OperationCanceledException){return Result.Failed;}if (re != null){FamilyInstance col = revitDoc.GetElement(re) as FamilyInstance;//GetGeometryObjectFromReferenceobtain an edge selected by userEdge geo_edge = revitDoc.GetElement(re).GetGeometryObjectFromReference(re) as Edge;Curve cur_geo = geo_edge.AsCurve();Options opt = new Options();puteReferences = false;opt.View = revitDoc.ActiveView;GeometryElement geoElement = col.get_Geometry(opt);Line transColumeEdge = null; //转换后的柱子的一条边Transform trans = null;foreach (GeometryObject geo_Obj in geoElement){if (geo_Obj is GeometryInstance){GeometryInstance geoInst = geo_Obj as GeometryInstance;trans = geoInst.Transform;break;}}if (trans != null){XYZ edge_start = cur_geo.GetEndPoint(0);XYZ edge_end = cur_geo.GetEndPoint(1);XYZ trans_edgestart = trans.OfPoint(edge_start);XYZ trans_edgeend = trans.OfPoint(edge_end);transColumeEdge = Line.CreateBound(trans_edgestart, trans_edgeend);}}return Result.Succeeded;}}}
总结：不管是链接模型坐标系还是族坐标系，要想要转换其中坐标为模型坐标的核心就是得到实例对象的TransForm，链接模型是reference ->Element—>RevitLinkInstance。族是得到reference—>Element—>FamilyInstance—>GeometryElement—>GeometryInstance.Transform。
.11.27日补充：
当一个Revit项目中存在一个Revit链接模型，Revit链接模型中有一个柱子（族），要想获得柱子的某一边的坐标需要进行的坐标转换步骤如下，首先，获得族实例的Trans，然后进行第一次转换，然后获得链接文件的Trans，将第一步获得的结果进行第二次转换。经过两次转换后才能得到柱子上某点的模型坐标。（此结果花了大半天才总结出来，虽然简单，以此告诫自己，做事情首先思考，明明很简单的转换关系，不思考，一点一点的试，费时费力！）
