YOUNG PROFESSIONAL
has yet to feature in an R package, so I decided to use ArcMap. After all, I had previously done this work in ArcMap and didn’t want to waste time on another approach that might not work.
In Praise of Open Source GIS Software
Cortney Cameron, YP-0359
It’s something of a running joke at my job that I’m obsessed with R, an open source programming language popular for statis- tical computing and graphics. What takes 25 columns of formulae in Excel or 25 steps (with nuisance intermediate shapefiles) in ArcMap can typically be reduced to a few simple – and important- ly, reproducible – lines of code in R. As a user-friendly language with powerful and versatile data analysis options (hundreds of useful packages are a search query away), R’s potential is hard to overstate. Some months ago, however, I needed to delineate a watershed using a drainage point and a DEM. Watershed delineation is one of those rare items that (to my knowledge)
As this was for a personal project, I loaded up my ArcMap .mxd file on my personal laptop and got to work – or I would have, except that ArcMap continually crashed while trying to run just the first step. Granting that my laptop was aged, I moved the project to my more powerful desktop computer, only to encounter the same slowness. I spent an hour optimizing ArcMap using the usual canned tricks before giving up in frustration. Some weeks later, I attempted once more, only to be greeted by a licensing error that mocked my perfectly valid and unexpired license. Annoyed by this erroneous claim and unable to quickly resolve it, I decided to jump ship to an open source alternative. If the alternative was slow, so is ArcMap, and at least it wouldn’t nag about expensive licenses!
Fortunately, thanks to an unrelated project involving unsu- pervised classification of satellite imagery, I already had QGIS with GRASS installed on my laptop. QGIS is an open source GIS software, and GRASS is a powerful programming toolbox that easily links into the program. A quick search revealed that this combination gave me the ability to delineate watersheds, so I opened QGIS and dragged in my DEM and drainage point. A few fast button-clicks later, I had a lovely and accurate watershed. I was blown away by how fast and easy the process was – and it was completely free.
Compared to R, I admit that ArcMap holds appeal for certain tasks – such as conveniently scrolling through projected geospa- tial data or easily creating professional maps with drag-and-drop capabilities, for example. Plus, some users prefer not to deal with code. However, after my QGIS experience, I’m astounded at its low market penetrance compared to ArcMap. With a decent GUI and a robust feature set, QGIS (especially with GRASS) can deliver almost anything the user demands – quickly and for free. Price aside, ArcMap has seemingly grown bloated and slow over time – the inevitable consequence of its unparalleled market share (I confess I’ve yet to try ArcGIS for Desktop, so maybe that platform has addressed performance complaints). Fig.1 is an example of a simple map made quickly using R.
That said, I acknowledge that ArcMap revolutionized GIS software and continues to offer key features; some of its tools (Network Analyst comes to mind) and third-party extensions probably haven’t been fully replicated elsewhere.
Figure 1 - A simple map made almost entirely in R (the callout lines were added in a photo editor).
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