topic Re: Convert Labels/Annotation to Points using Python 9.3, get centroids in Python Questions

Convert Labels/Annotation to Points using Python 9.3, get centroids

DonovanCameron — Mon, 09 May 2011 21:29:08 GMT

I have a problem where I need to generate a point for every label but would like to do it with python using the shape geometry and have came up with the following results...

[ATTACH]6443[/ATTACH]

The red '0' is the actual label from the feature class, it is being drawn dynamically (not stored as annotation)

When using Calculate Geometry and

!shape.Centroid.*!

they share the same location, like a weighted/centre of gravity point.

The

!shape.Centroid.*!

and

!shape.LabelPoint.*!

return the same point, and neither is actually on the label point...

A workaround, is to convert the labels to annotation (in a gdb), then add two new x/y fields and calculate the geometry of those, then create an XY theme from those two fields. Note that the x/y given will be a bounding box of the annotation, so multi-line labels can affect this. I generate x/y on a label with a single character.

But like I mentioned, a python solution would be nice. The shape.LabelPoint sounded so promising!

Re: Convert Labels/Annotation to Points using Python 9.3, get centroids

BradPosthumus — Wed, 11 May 2011 12:49:38 GMT

We had to do something similar so we could use ArcMap's label engine to determine the label placement for MapServer WMS's. The process is similar to your workaround:

1. Turn on labels for an ArcMap layer.
2. Convert to an annotation feature class, saved in a file gdb.
3. Re-position the annotation features if necessary.
4. Use the Feature-to-point tool (Data Management->Features) to convert the annotation to a point feature class, using the CENTROID as the point placement option.

Unfortunately there is bunch of manual work involved (steps 1-3). Step 4 we use in a Python script since we perform a number of other processes on the output point file.

Your problem with "LabelPoint" sounds familiar. I vaguely recall testing it and getting the same results as you, and then abandoning it. Maybe it works better in 10?

Re: Convert Labels/Annotation to Points using Python 9.3, get centroids

DonovanCameron — Wed, 11 May 2011 17:51:28 GMT

4. Use the Feature-to-point tool (Data Management->Features) to convert the annotation to a point feature class, using the CENTROID as the point placement option.

Nice suggestion, it gets rid of the step to create and populate two x,y fields.

I tried the shape.LabelPoint in v10 SP1 and found the same results as before.