Placing point symbol on center of polygon in ArcMap?

Placing Point Symbols at the Center of Polygons in ArcMap: A Definitive Guide (Humanized Version)

So, you’ve got a map, and you want to stick a point right smack-dab in the middle of a polygon? Makes sense! It’s a super common task in GIS, and there are tons of reasons why you might want to do it. Maybe you’re showing the population center of a city, or perhaps you need to calculate how far a cell tower is from the heart of a protected forest. Whatever the reason, ArcMap’s got your back. Let’s dive into how to get it done.

ArcMap offers a few different ways to tackle this, each with its own little quirks and advantages. The easiest? Probably the “Feature To Point” tool. But hey, there are other options too, like calculating those center coordinates yourself or even whipping up a Python script if you’re feeling fancy. Let’s break it down.

The “Feature To Point” Tool: The Quick and Dirty Method

Think of the “Feature To Point” tool as your one-stop shop for polygon-to-point conversions. It’s tucked away in the Data Management toolbox, and it’s pretty darn simple to use. Basically, it takes your polygon layer and spits out a new point layer, with each point sitting right at the calculated center of its original polygon.

Here’s the lowdown:

Boom! You’ve got a point layer with points sitting pretty at the center of your polygons. The tool even copies over all the attribute information from your original polygons, so you don’t lose any data. Now you can style those points however you like!

Calculating Centroid Coordinates: Getting Your Hands Dirty

Okay, so maybe you’re a bit of a control freak (no judgment!) and want to get down and dirty with the coordinates yourself. Or maybe you need those X and Y coordinates stored as actual attributes. No problem! This method lets you calculate the centroid coordinates and then create a point layer from scratch.

Here’s how we roll:

Python Scripting: For the GIS Wizards

Alright, if you’re comfortable with Python and ArcPy, you can automate this whole process with a script. This is especially useful if you need to do this a lot, or if you want to build it into a larger workflow.

(See the original article for the python script)

How to unleash the script:

Troubleshooting: When Things Go Wrong

• Centroid MIA (Missing In Action): If your centroid is wandering outside the polygon, remember that “Inside” option in the “Feature To Point” tool. Or, if you’re scripting, you might need to add some logic to force the point inside.
• License blues: The “Feature To Point” tool needs an ArcGIS Advanced license. If you’re rocking a Basic or Standard license, the Calculate Geometry method is your friend.
• Coordinate system chaos: Make sure your coordinate systems are all playing nicely together. Mismatched coordinate systems can lead to all sorts of weirdness.

Wrapping It Up

Placing points at the center of polygons is a GIS bread-and-butter task. Whether you go for the simplicity of the “Feature To Point” tool, the hands-on approach of calculating coordinates, or the automation power of Python, you’ve now got the knowledge to conquer those centroids! So go forth and map!