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Z-Coordinate Interpolation

StefanVollnhofer

Hey there!
I've imported the surveypoints from an ascii file (add xy data -> export as shape -> import) and got the points now with x y and z coordinates in my map as shape-file.
How can i interpolate z-coordinates to new points now? I've selected the field "contains z coordinates" in the feature class?

Thanks!

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Accepted answers

jskinner

Hi Stefan,

I misunderstood what you were looking to accomplish before. You are looking to populate the elevation values that are NULL by interpolating the elevation values from the surrounding points. Is that correct?

You can do this by performing the following:

1. Select all elevation values that are not NULL (i.e. NOT GelaendeH IS NULL)
2. Run the IDW tool on the selection. Before executing the tool, click on the Environments button > Processing Extent > set the Extent to the point feature class
3. Run the Interpolate Shape tool on the point feature class using the output raster from the IDW tool. A new feature class will be created
4. With the new feature class, select all elevation values that are NULL (i.e. GelaendeH IS NULL)
5. Open the attribute table > Right-click on the GelaendeH field > Calculate Geometry > Z coordinate of point

All comments

StefanVollnhofer

Okay, this is now exactly what I was looking for!!!! Thank you very much for your help and patience!!! Saved me a lot of time and work!!

StefanVollnhofer

Hey JSkinn3!

Seems really good to me, I'll try this after christmas in the office, thank you so far!!

jskinner

StefanVollnhofer

should it not be something like:

for row in cursor:
if not vertexElevation > 0:
vertexElevation = something with interpolate z-values of the next 10 neighbours or all points in the area of 10 metres (thats the question)

without an else i would say because i want the rows with values to stay the same, but only the <null> values to be interpolated.
any further ideas? thank you, for you informations so long

StefanVollnhofer

The script now works (running for a while), but don't update any z-values... <null> values are still in the row.

This script will set the <null> values only to "0" right? Or does it interpolate the other values? I dont want to update the given z-values (because they were taken by a survey) but only the <null> values to be interpolated.

jskinner

Looks like the issue was with the NULL values in your field, and the query in the MakeFeatureLayer function was slightly off. Try the following:

shp = "WaEinbauten"
 
with arcpy.da.SearchCursor(shp, ["GelaendeH"]) as cursor:
    for row in cursor:
        if not vertexElevation > 0:
            vertexElevation = 0
        else:
            vertexElevation = row[0]
        arcpy.MakeFeatureLayer_management(shp, "pts_lyr", "GelaendeH = " + str(vertexElevation))
        arcpy.Adjust3DZ_management("pts_lyr", "NO_REVERSE", vertexElevation)

StefanVollnhofer

Ok, it worked for me but here is the copied gdb file

file_gd_wasser.gdb.rar

jskinner

Hi Stefan,

I could not access this database. It seems to be corrupted. Can you copy the feature class to a File Geodatabase and send that?

StefanVollnhofer

I've uploaded a sample of my mdb file to uploaded.to:

http://ul.to/0dynvo2x

password is "esri"

I have tried it now to locate the copy of the feature class within and outside the feature dataset but it didn't word for me. Thanks for your patience 😉

jskinner

Can you upload a sample of your data?

StefanVollnhofer

Yes, they are Point Z and in the Feature Class Options I have selected the option "Contains Z-Values"

jskinner

Stefan,

Is your input feature class Z-enabled? You can check by opening the attribute table. The value for the Shape field should be 'PointZ'.

StefanVollnhofer

You're probably right that this is not a good idea, but the (same) error is still there 😞

used code now:

import arcpy
... from arcpy import env
... env.overwriteOutput = 1
...  
... shp = r"S:\Public\Projekte\2011\11420\WVA Hochneukirchen\wasser.mdb\LK\WaEinbauten"
... shp_copy = r"S:\Public\Projekte\2011\11420\WVA Hochneukirchen\wasser.mdb\LK\WaEinbauten_copy"
... 
... arcpy.Copy_management(shp, shp_copy) 
... 
... with arcpy.da.SearchCursor(shp_copy, ["GelaendeH"]) as cursor:
...  for row in cursor:
...   vertexElevation = row[0]
...   arcpy.MakeFeatureLayer_management(shp, "pts_lyr", "Elevation = " + str(vertexElevation))
...   arcpy.Adjust3DZ_management("pts_lyr", "NO_REVERSE", vertexElevation)
...

Error:
Runtime error Traceback (most recent call last): File "<string>", line 14, in <module> File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\management.py", line 2101, in Adjust3DZ raise e ExecuteError: ERROR 000204: Fehler beim Erstellen des Eingabe-Feature-Cursors Fehler beim Ausführen von (Adjust3DZ).

Tried it also with "shp_copy" in line 12 instead of "shp"
Thanks for your help so far!

FabianBlau

I guess, its no good idea to change a shp-file within a searchcursor using this shp-file.
Maybe you should copy the shp-file and use the copy in the cursor:

shp = r"S:\Public\Projekte\2011\11420\WVA Hochneukirchen\wasser.mdb\LK\WaEinbauten"
shp_copy = r"S:\Public\Projekte\2011\11420\WVA Hochneukirchen\wasser.mdb\LK\WaEinbauten_copy"

arcpy.Copy_management(shp , shp_copy) 

with arcpy.da.SearchCursor(shp_copy, ["GelaendeH"]) as cursor:
...

StefanVollnhofer

Hey, I've tried your python code for my file but there were the following error

>>> import arcpy
... from arcpy import env
... env.overwriteOutput = 1
... 
... shp = r"S:\Public\Projekte\2011\11420\WVA Hochneukirchen\wasser.mdb\LK\WaEinbauten"
... 
... with arcpy.da.SearchCursor(shp, ["GelaendeH"]) as cursor:
...    for row in cursor:
...       vertexElevation = row[0]
...       arcpy.MakeFeatureLayer_management(shp, "pts_lyr", "Elevation = " + str(vertexElevation))
...       arcpy.Adjust3DZ_management("pts_lyr", "NO_REVERSE", vertexElevation)
...       
Runtime error  Traceback (most recent call last):   File "<string>", line 11, in <module>   File "c:\program files (x86)\arcgis\desktop10.2\arcpy\arcpy\management.py", line 2101, in Adjust3DZ     raise e ExecuteError: ERROR 000204: Fehler beim Erstellen des Eingabe-Feature-Cursors Fehler beim Ausführen von (Adjust3DZ).  
>>>

Which means that the Input-Feature-Cursor could not be created, and the Adjust3DZ could not be run (I'm running the german version of ArcGIS)
I've updated the path to my feature-class (wasser.mdb\LK\WaEinbauten) as well the elevation field (GelaendeH).

jskinner

Yes, you will just need to change the 'shp' variable to the path of your feature class in the MDB. Ex:

shp = r"c:\data\mydb.mdb\<feature class name>"

You will not want to end the feature class name with a .shp since it is not a shapefile.

StefanVollnhofer

Seems like a very good solution to my problem but is this also possible if the shape is within a .mbd database?

tried it with "c:\data\mydb.mdb\z.shp" but it doesnt work. Do you have an idea how i can run this script for my data?

jskinner

You can run the following python script to update the Z value of each point:

import arcpy
from arcpy import env
env.overwriteOutput = 1

shp = r"C:\data\pointsZ.shp"

with arcpy.da.SearchCursor(shp, ["Z"]) as cursor:
   for row in cursor:
      vertexElevation = row[0]
      arcpy.MakeFeatureLayer_management(shp, "pts_lyr", "Elevation = " + str(vertexElevation))
      arcpy.Adjust3DZ_management("pts_lyr", "NO_REVERSE", vertexElevation)

You will just need to update the path for the 'shp' variable to your shapefile and change the field name ('Z') in the arcpy.da.SearchCursor to the elevation field name. The code iterates through each point and updates the Z value based on the elevation field.

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