前言

这个例子通过从图片中获取颜色，将颜色转换成数值，赋值给分割表面上对应族实例的对应参数。

内容

获取颜色的代码：

Bitmap image = new Bitmap(doc.PathName + "_grayscale.bmp");
System.Drawing.Color pixelColor = new System.Drawing.Color();
pixelColor = image.GetPixel(image.Width - v, image.Height - u);

获取族实例的代码：

DividedSurface ds = element as DividedSurface;
GridNode gn = new GridNode();
gn.UIndex = u;
gn.VIndex = v;
FamilyInstance familyinstance = ds.GetTileFamilyInstance(gn, 0);

设置族实例参数的代码：

double grayscale = 255 - ((pixelColor.R + pixelColor.G + pixelColor.B) / 3);
Parameter param = null;
param = familyinstance.LookupParameter("Grayscale");
param.Set(grayscale / 255);

保留核心逻辑，去除错误处理相关逻辑：

Parameter param = null;
Bitmap image = new Bitmap(doc.PathName + "_grayscale.bmp");
FilteredElementCollector collector = new FilteredElementCollector(doc);
ICollection<Element> collection = collector.OfClass(typeof(DividedSurface)).ToElements();
foreach (Element element in collection){
   DividedSurface ds = element as DividedSurface;
   GridNode gn = new GridNode();
   for (int u = 0; u < ds.NumberOfUGridlines; u++){
      gn.UIndex = u;
      for (int v = 0; v < ds.NumberOfVGridlines; v++){
         gn.VIndex = v;
         if (ds.IsSeedNode(gn)){
            FamilyInstance familyinstance = ds.GetTileFamilyInstance(gn, 0);
            if (familyinstance != null){
               param = familyinstance.LookupParameter("Grayscale");
               System.Drawing.Color pixelColor = image.GetPixel(image.Width - v, image.Height - u);
               double grayscale = 255 - ((pixelColor.R + pixelColor.G + pixelColor.B) / 3);
               param.Set(grayscale / 255);
            }
         }
      }
   }
}

结果