Calculating overlapping areas

Welcome Notes

1197

A frequently requested GIS operation for Team Tuco-tuco is calculating the overlapping areas of individually marked tucos.

First  of all, make sure you have ArcGIS. To install your own copy, request a free license as a UC Berkeley student or use a workstation in MVZ:
All the installation steps are outlined there.

In ArcGIS,
1)  import your points. If you’re not sure how to do that, see tutorials (https://mvzgis.wordpress.com/workshops/beginners-intro-to-gis/). Verify they are showing up and you can see all your attributes.
2) Calculate minimum convex hulls, which can be done with the Minimum Bounding Geometry Tool (use the search toolbar)
3) Next use the Tabulate Area tool in ArcGIS, which will create a table of results. (You will need Spatial Analyst extension enabled)
Be sure to set the Zone Id and the Class Id as the same parameter, in this case it was “tucoid”

Tip: copy the python snippet to repeat these steps for more datasets.
# Replace a layer/table view name with a path to a dataset (which can be a layer file) or create the layer/table view within the script
# The following inputs are layers or table views: “xy.shp”,”x_hulls”, “x_hulls”
arcpy.MinimumBoundingGeometry_management(“xy.shp”,  “c:/output/x_hulls.shp”, “CONVEX_HULL”, “NONE”)
arcpy.TabulateIntersection_analysis(in_zone_features=”x_hulls”,zone_fields=”x_hulls.tucoid”,in_class_features=”x_hulls”,out_table=”C:/Users/Michelle/Downloads/shapefiles/intersect_table_classtucoid.dbf”,class_fields=”x_hulls.tucoid”,sum_fields=”#”,xy_tolerance=”#”,out_units=”UNKNOWN”)
This can be also turned into a standalone python script, with more convenient variables for input and output files, if you need to go into industrial-strength analysis.
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s