Simplify Your Workflow with the Spatial Join Tool

August 17, 2009 by Timothy
Filed under Analysis, ArcGIS, GIS Tips

One of the benefits of GIS is the ability to summarize relationships between different types of data.

In this example, a relationship is determined between students and study sectors. Students being a point layer and study sectors being a polygon layer. Determining the number of students within each sector is easy to do by simply counting the visible points for each area. The is not always correct as some points can fall on top of each other. You can use the select by location tool to find the exact number of student within each sector, but this can become time consuming if you have a lot of areas to cover. The solution to this problem is the spatial join tool. This tool determines the spatial relationship between the polygons and points. A point count for each polygon is created and placed in the attribute table.

Here is a demonstration video:

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Download the video to your computer: ArcMap Spatial Join Tool

Tags: Analysis, Attribute Table, Count, point, polygon, Spatial Join, Sum

ArcGIS Geodatabase Benefits

December 3, 2008 by Timothy
Filed under ArcGIS, Data Management, GIS Tips

3 Comments

I was just recently doing a spatial join between a polygon shapefile and a point feature class file. There were approximately 400 polygons and 38,000 points. There were several fields within the point file which were being summarized based upon which polygon they fell within. The entire join process took about an hour. I then took the output file, which was a geodatabase polygon feature class and joined it to a similar point file. Amazingly, that join process only took 5 minutes.

This is just one example of the efficiency of the Geodatabase. Geoprocessing is so much quicker. A savings of time is a savings of money. Here are a few other things to know about the various types of geodatabases.

Personal Geodatabase

Single User Editing
Stored in Access Database File
2 GB Max Size

File Geodatabase (ArcGIS 9.2+)

Single User Editing
Stored in a Folder
Efficient Data Structure for Increased Performance
1 TB per Table Max Size

SDE Geodatabase

Multiuser Editing
Disconnected Editing
Stored in a RDBMS

Additionally, with the geodatabase you can create:

Topologies
Geometric Networks
Feature Linked Annotation
Relationship Classes
Sub Types and Domains
A Centralized location for all the geographic data

So with these benefits of the geodatabase, try converting some of your data. Creating a geodatabase does not take long as you can find out in my 90 Second Geodatabase post. Also, ESRI has a great blog post entitled: Migrating your existing data into the Geodatabase. It goes into great detail into how to import the following file types into the geodatabase.

Shapefiles
Coverages
CAD
Tables
Imagery

Try out the geodatabase today, you will find many benefits. If it seems a little awkward, give it time as you will get adjusted to the concept. There is nothing to loose. If you don’t like it then delete the geodatabase and go back to using your shapefiles.

Good Luck!