How to 'Interpolate' features to a surface without creating a seperate file?

[ChrisStephens1]

Is there way to do what the 'Interpolate Shape' tool does but calculates the z values into the Shape field of the input feature instead of making a new output? As far as I can tell the only other way is by using the 3D Analyst toolbar and selecting the 'Interpolate' tool based on the geometry I need but I'd rather not have to click that every time I digitize something but would prefer to do it after all my features at once after they're created. 'Interpolate Shape' does that but makes a separate file, which does not fit into my workflow. Is there another way? Perhaps using the Field Calculator?

[DanPatterson_Retired]

None exist.  You could experiment witth scriptting the process, generating the output in memory, deleting the original (if possible) and replacing it.  Whether this could be done in one step... I am not sure.

Interpolate Shape—Help | ArcGIS for Desktop

[XanderBakker]

Indeed as Dan states, it is most unlikely that you can if the featureclass has not yet the Z values enabled.

Suppose you have a Polyline featureclass (Shapefield will contain "Polyline" not "Polyline Z"). When you create the featureclass, you specify if Z (and M) values are enabled. If Z is not enabled, you can set the Z values of the vertices, but they will not be stored. If the featureclass has Z values enabled on creation but you do not set them initially, you can update the Z values without creating a new output (although this would require some scripting).

[ChrisStephens1]

> it is most unlikely that you can if the featureclass has not yet the Z values enabled.

Z Values are enabled for my feature classes! Shape field has a value of 'Polyline Z'.

>If the featureclass has Z values enabled on creation but you do not set them initially, you can update the Z values without creating a new output (although this would require some scripting).

This is what I need to do. Is there any more information on this method?

[XanderBakker]

OK, you have polylines with Z enabled, yet Z has no value assigned yet.

What I would do in this case is create a tmp point featureclass with the vertices of the polygons and information on original OID of the polyline, part number and point number (to be able to link the vertice after Z has been defined back to same vertice in the polyline). Next, assuming you have spatial analyst available, is use the tool extract values to points to extract the Z value for each point into a new tmp featureclass (you could do this using the IN_MEM workspace, but it depends on the amount of points, if this will work in memory).

The next step would be to create a search cursor and fill a dictionary from the points with the Z values as attribute (use OriginalOID_PartNumber_PointNumber as key and the Z as value) and use this when you create the update cursor to update the Z value if the individual vertices.

You can find detailed information on working with 3D geometries in arcpy in my blog post here: Working with 3D and M-aware geometries in Arcpy

[ChrisStephens1]

Thank you for the reply. That sounds like it would work, but again I just want the z values calculated in the existing dataset, no temp files or output files. I guess it's impossible, save for using the 3D Analyst Toolbar 'Interpolate' for every feature I create. I'm trying to streamline a very large data collection workflow.

[XanderBakker]

There are always solutions... See an alternative method pointed out in this document: Extract Raster Values using Numpy

[ChrisStephens1]

That's disappointing! Thanks for the reply