From a Different Angle: Averaging Upslope Aspect

In flow accumulation modeling, a common bit of data needed is the average upslope value of a parameter of interest, such as slope or curvature.  In most cases, this is simply a matter of calculating a flow accumulation weighted by the parameter in question, then dividing this by the unweighted flow accumulation.  But what if you want average upslope aspect?  Since aspect is measured in degrees, and a value of 0° and 360° are the same, a simple arithmetic mean will be useless.  So, what to do? In this post, I will walk you through the process of calculating the mean upslope aspect using ArcGIS, and leave you with a working python script that will automate the process.

Raw aspect raster, in ArcMap's default Technicolor scheme.
Raw aspect raster, in ArcMap’s default Technicolor scheme.

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MAPCITE Addin Update: Excellent Customer Service

As you may recall from my review of MAPCITE’s Excel Addin, I was having trouble with the polyline and poly shape features.  Originally, I was going to just update the original post with the response from customer service, but their amazing turnaround time merits a full-fledged followup post.  I had emailed customer service about my problem, and they responded the same day that they would forward it to the development team.  The next morning, their was an email in my inbox informing me that they had fixed the bug with the software and tested it.  I downloaded the new version and installed it, and I was able to make polygons and lines!

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MAPCITE Excel Addin: Quick and Dirty Review and How-To

This week, I’ve taken MAPCITE’s Excel plugin for a quick test drive to see what it can do.  I’m not getting any money, endorsements, or other compensation for this, so these are my own thoughts on the product.  The software is easy to install and easy to use, and provides valuable added functionality to Excel. There were some limitations and a few stumbling blocks, but overall this is a useful product.  Read on for the full report.

Looks like it’s always been there!

Continue reading “MAPCITE Excel Addin: Quick and Dirty Review and How-To”

Spreadsheet Mapping Tools: the Next Big Thing?

So, let’s say you need a map. And let’s say you don’t know much about this whole GIS thing. Wouldn’t it be nice if you could just take your spreadsheet of addresses or lat/long points and make a map, just like you would make a chart or graph? Well, the folks at ESRI, MAPCITE, and the LibreOffice Community all thought so, and have developed spreadsheet extensions to help you do just that. This has huge potential for spatially empowering the spreadsheet-enabled public, as well as reserving valuable GIS analyst time for more complex projects.

The future?
Complete dramatization.

These extensions have a huge range in terms of number of capabilities and end-user cost (free to as much as you care to pay).  Over the next few weeks, my mission is to compare these mapping extensions and see how they stack up.  Which one is the “best”?  What do you get for your money?  Just how good of a map can you make with a spreadsheet, anyway?  I’ll be exploring these questions, one extension at a time, and summarizing the results in a final post at the end.  Stay tuned for review #1: MAPCITE’s Excel®™ Add-In.



Photo credit: Emma Rearick

Hello!  I’m Jay Guarneri, a Master’s student at the School of Forest Resources.  I’m currently studying landscaping modeling using Geographic Information Systems (GIS), but I maintain diverse interests such as marine biology, food & wine, and art.  In the weeks and months to follow, you can expect to see musings on geography and cartography, how-to guides for GIS analyses in various software platforms, and announcements and reviews of new GIS software and developments.