ArcGIS Desktop – Cutting Rectangles into Triangles Using ArcMap

arcgis-desktoparcmapfeaturessplitting

I have some large features that I need to split into smaller pieces for terrain alignment through vertices in another program. I figured triangles would be the best solution.

So basically I want to turn this:

enter image description here

into this:

enter image description here

Sadly the latter image is a mockup. I had some success with the fishnet tool and intersecting to create rectangles, but I can't get triangles out of it. Rotating the net doesn't work because the rectangles aren't square. Any ideas that don't involve manual cutting?

Best Answer

One of multiple solutions. Create points inside polygon, fishnet will do. Add vertices of polygons to this set. Create TIN. Export tin triangles and clip them: enter image description here

Updated answer on points creation. Script below works from ArcGIS and takes 3 parameters:

  1. Layer in TOC. Used to define extent.
  2. Distance between points, type double
  3. Points layer (empty)

import arcpy, traceback, os, sys extentLayer = arcpy.GetParameterAsText(0) xStep = float(arcpy.GetParameterAsText(1)) destLayer = arcpy.GetParameterAsText(2)

try:
    def showPyMessage():
        arcpy.AddMessage(str(time.ctime()) + " - " + message)
    def isLayerExist(lName):
        layer = arcpy.mapping.ListLayers(mxd,lName)[0]
        ext=layer.getSelectedExtent()
        return (layer,ext)
    mxd = arcpy.mapping.MapDocument("CURRENT")
    destLayer, anExt=isLayerExist(destLayer)
    extentLayer, anExt=isLayerExist(extentLayer)
    yMin,yMax,xS,xE=anExt.YMin,anExt.YMax,anExt.XMin,anExt.XMax
    yStep=xStep/2*math.pow(3.0,0.5)
    curT = arcpy.da.InsertCursor(destLayer,"SHAPE@")
    p=arcpy.Point()
    iMax=int((yMax-yMin)/yStep)+2
    jMax=int((xE-xS)/xStep)+2
    for i in range(iMax):
        Y=yMin+i*yStep
        xStart=xS+i%2*xStep/2
        xEnd = xE +i%2*xStep/2
        for j in range(jMax):
            X=xStart+j*xStep
            p.X,p.Y=X,Y
            theRow=(p,)
            curT.insertRow(theRow)
except:
    message = "\n*** PYTHON ERRORS *** "; showPyMessage()
    message = "Python Traceback Info: " + traceback.format_tb(sys.exc_info()[2])[0]; showPyMessage()
    message = "Python Error Info: " +  str(sys.exc_type)+ ": " + str(sys.exc_value) + "\n"; showPyMessage()
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