Creating 3D line from points with python

MartinSirkovsky

Hi.

I have a series of points with X,Y,Z coordinates. I am trying to create a polylines from the points. Points should be vertexes of the polyline and Z-Coordinate should be used to define the elevation of vertexes.

I have created a script which works, but the Z-Coordinate is lost on vertexes and is recorded as ZERO. I am sure that my script is correct because if I pass the Z-Coordinate into the M value, it is recorded correctly. The part of the script which creates the line can be seen below:

vertexArray = arcpy.Array()

     for points in pointArray:

     xCoord = valueX

     yCoord = valueY

     zCoord = valueZ

         

     # valueZ is also passed to M dimension to test if there are some problems with values

     currentPoint = arcpy.Point(valueX, valueY, valueZ, valueZ)

     vertexArray.add(currentPoint)

newLineCursor = arcpy.da.InsertCursor(outputFc, ["SHAPE@"])

  polyline = arcpy.Polyline(vertexArray)

  newLineCursor.insertRow([polyline])

The script runs wihtout problems, and the polylines are created. But when I check in ArcMAP the polyline under sketch properties all the vertexes on line have null as Z-Coordinate (see image bellow).

I have just tested to convert points with arcpy.PointsToLine_management, and it works correctly. I could implement this in my script, but I am still curious as to why is Z-Coordinate not recorded properly with my script.

Thanks,

Martin

MartinSirkovsky

I have tried a different approach and got it to work. Actually what I am trying to accomplish is to convert line file to 3D based on points. As it is not possible to snap 3D in ArcMap the lines constructed from surveying points in ArcMap are placed on zero elevation. After the lines are constructed, I am using the point file to change the elevation on the vertexes to the original one. The working script can be seen here:

import arcpy

shapeFileFolder = "folder where the files are located"

fileToProcess = "line or polygon file"

fileWith3DPoints = "file with 3D points which were used to construct the lines"

arcpy.env.workspace = shapeFileFolder

arcpy.env.overwriteOutput = True

def convertTo3D(fc, zPoints):

  # Dictionary to hold the point coordinates (key: x,y coord, value: z coord)

  zCoordDict = {}

  # Create an array which will hold geometries of point feature class

  fields = ["SHAPE@X","SHAPE@Y","SHAPE@Z"]

  with arcpy.da.SearchCursor(zPoints, fields) as cursor:

  

    for row in cursor:

     # round the coordinates to 3 decimal places

      xCoord = round(row[0], 3)

      yCoord = round(row[1], 3)

      zCoord = round(row[2], 3)

      # add key:value for current point to the dictionary

      zCoordDict[str(xCoord) + "," + str(yCoord)] = zCoord

  # Update Z coord in input file

  fields = ["SHAPE@X","SHAPE@Y","SHAPE@Z"]

  cursor = arcpy.da.UpdateCursor(fc, fields, None, None, True)

  for row in cursor:

       # Get x,y coordinates of current point

       xCoord = str(round(row[0],3))

       yCoord = str(round(row[1],3))

       newZCoord = zCoordDict[xCoord +"," + yCoord]

       print "New Z coordinate for current point is %s" % (newZCoord)

            row[2] = newZCoord

       cursor.updateRow(row)

# Run the function

convertTo3D(fileToProcess, fileWith3DPoints)