Tag Archives: projections

On Cartography: Maps Can Lie – Here’s How We Avoid That

Regardless on where you stand with the DAPL situation (I’m anti-DAPL but that’s a different conversation), pipelines and their safety are on people’s minds. There are certainly many ways to analyze these safety concerns, and one great way is through maps. However, like any other news source, maps can lie, and when they lie, people can misunderstand the situation and be misled. As a lover of cartography and the benefits it offers the world, seeing a map that is poorly constructed and potentially lying widely shared sets me on fire. Maps are so incredibly useful, and I love when people turn to maps to understand their world a bit better, but if those maps can’t hold up to critical analysis, they cause people to lose trust in the medium, but also wonder if maps are a worthy pursuit at all.

I recently dealt with this situation with this map on the dangers of pipelines in the U.S. It’s a video lapse that displays all pipeline-related deaths, injuries, oil spills, and a category referred to merely as “Natural gas” in the U.S. since 1986 to present day. There are many, many issues with it, and while I would love to point them out in detail, I want to point to it as an example of what a person unfamiliar with map basics should look for to ensure they’re reading a map worthy of their time:

1. Is it projected?

I’ll admit – unprojected maps are one of my biggest pet peeves in the whole wide world of mapping. This points to my background as a student who took a course in the principles of GIS, but the fact is, when a map is unprojected, there’s a good chance its wrong. Not all maps need to be projected of course, but standalone maps such as the one above does. The U.S. is an easy map to see if it’s projected or not – the states first off look weird, but most U.S. map projections curve the U.S., which is most noticeable in the North, where when unprojected, Washington, Idaho, Montana, North Dakota, and Minnesota all appear to have incredibly straight edges. A map projection is an attempt by the cartographer to display an area as closely to the way it would look on the globe. It is an attempt in accuracy of where things are. When a map is unprojected, nothing on it is as close to where it should be as where it would be when projected. Here’s an example of what a projected U.S. map should look like versus an unprojected map:

ch2_usanoproj
An unprojected map from http://mama.indstate.edu/users/geboen/ch2_f99.html
threepro
An example of several projected maps, by Peter H. Dana of University of Colorado-Boulder

2. Is the data source clearly available?

Sources, sources, sources! The good news about GIS information is that it’s harder (or at least not as worth it) to come up with fake map information, but the issue is that maps lie, and a lot of that comes from the way the cartographer chooses to display the information. Data can be manipulated in so many different ways, which is why its always good to see an attribution to the data sources on the map – you can confirm that the data comes from a reputable source, which is thankfully the case with this map, as it comes from the U.S. Department of Transportation.

3. Is the legend telling you everything about what’s going on with the map?

In the case of this map, there isn’t a ton of clarity – one of the symbols is defined as “Hazardous liquids (mostly oil)” which doesn’t actually tell you when those liquids are. What do they mean by “mostly”? How do they measure what is “mostly”? By half? By 80%? It would make more sense for the sake of clarity to have a list of what those liquids can be, or at least what percentage of the liquids are oil. Also, note that it also says the points for that category are scaled by spill size, but do not show you what the scale is or what they mean by size – is it measured in the amount of liquid spilled or the area covered?

The point is, your legend is supposed to clarify what appears on the map. It should be simple and straightforward, and answer any basic questions you may have about the information on the map. That’s not quite what happens here.

4. Can you tell who commissioned the map? 

Cartographers are often asked to make maps for people, businesses, and other entities. When this happens, it’s important to make it clear who asked for the map so that way any interests can be made known to the reader. It’s fine for an environmental group to request a map, but it is always worth knowing that they’re the ones who requested it so the reader can see for themselves why a cartographer might have left out or emphasized something on a map.

Those are the basics! I also think it’s important for a map to be visually appealing, but that’s just me and my cartographic eye. If you have any opinions or questions about evaluating maps for validity, please comment below!

Mapping the GIS Adventure – Lab 4: Maps Are Where “Y’all” and “Eh?” Can Be Said in the Same Breath

NunavutLab4

I remember this mapping assignment with strong feelings. This was our fourth assignment, and we were into our fifth week of the semester, and I was struggling a little when it came to these maps. I was also feeling inadequate, as I had not yet made friends in the class and was perceiving everyone around me to be plugging along just fine. Of course, actually, everyone was learning this new skill as I was, and we all probably would have benefited if we had started talking to each other a lot sooner. So the map that gave me such terror was actually pretty simple: provide a size comparison between the state of Texas and the Canadian province, Nunavut. Along with this, the skill we were to learn was that of projection, both on-the-fly and permanent.

If there's any question, I reprojected all of these themes into the Canada Lambert Conformal Conic coordinate system.
If there’s any question, I reprojected all of these themes into the Canada Lambert Conformal Conic coordinate system.

The requirements for this map were similar as those of the previous labs, but also required us to get a dose of ArcCatalog and create a table that listed all of the data that we were using for the Canada map, and their original projections, and then the projections we reprojected them to, which needed to be a conformal projection. These were to be permanent reprojections, while the Texas map didn’t require permanent reprojections, but instead on-the-fly projections.  Presently, this doesn’t seem hard at all. At the time, wrapping my mind around it was impossible. The biggest issue was merely that I didn’t understand that on-the-fly projection could trump permanent projections. So even though I reprojected all of my themes correctly, I never changed the coordinate systems of the data frame, so I never saw a difference, until I learned what was going on later.

One big thing: this was where we were supposed to learn the difference between the  “Define Projection” and actual “Project” tools. My professor warned us all, multiple times to be very, very careful that we understood the difference between the two. While I certainly had an unfortunate experience with this map, I do thank the heavens that I understood the difference almost immediately. It would probably have been the straw that broke the camel’s back otherwise.

Otherwise, this map is one of my favorite maps I’ve created so far. I won’t lie – it’s because I find it pretty. The raster I used to show the physiography of Canada utilizes the same color spectrum as most physiography maps, but never before have I wanted to wax poetic on one. That might just be a dedication to Canada’s physical appearance, and I’m not even ashamed. In terms of other map elements, we were also required to show the railroads and major roads of Canada and it took me a while to figure out which colors worked best, but I feel pretty good about my bright purple for major roads and midnight blue for railroads. And I must shout kudos to esri’s ArcMap railroad symbology. Well done.

Otherwise, we were also supposed to clearly highlight Nunavut and clearly show Iqaluit, the capital of Nunavut. You’ll note that someone has definitely learned to use the “select” tool, as Iqaluit is the only city on there. The only one. Hurrah for me, because when I first took a stab at this map, I still had the selection skills of Lab 2. As for highlighting Nunavut, I think I don’t do so as successfully as say, Texas is highlighted in the inset. This is partially due to the fact the physiography needed to be clear, but was also really strong. So even though Nunavut has a different overall coloring, a red outline, and two large names shouting out to the viewer, the eye is not immediately drawn to it. To rectify that, I would have probably made the physiography a lot lighter with transparency, so that way Nunavut would have stood out more. I also would have done something about the outline, such as a black outline to strengthen the border of it.

The inset of the Texas map was pretty easy. Texas was red, outlined in black, and the rest of the visible states were yellow, outlined in gray. Not too hard to make that work, given physiography wasn’t necessary. The only aspect I found giving me issue was the scale, but once I adjusted the data frame for the Texas map, I was able to have them at a matching scale. Based off of the map, I hope you all agree with me that Texas, while my favorite big state, is still definitely smaller than Nunavut. If you don’t, I’ve failed because Nunavut has some 500,000+ miles on Texas. No, not EVERYTHING is bigger in Texas…

As for my technical aspects of the map, such as the legend, scale bar, and North arrow, I’m pretty satisfied with my space usage and placement, though I definitely would have done well to somehow fit that scale bar directly beneath Canada, so that way the ends lined up with the edges of Nunavut. I just did the finger test myself and they totally would have matched up and would have saved a lot of readers the irritation of keeping their fingers the same width apart as they moved them to Nunavut.

What cracks me up now is how this map turned from a pain in my rear to truly, one of my favorite maps. Under the rules of our class, I was allowed one free lab that  could be turned in late with no late penalty. As we already had one lab due a week, I sat on this lab all the way to Spring Break to work on it with no other requirements breathing down my neck. I remember redoing the assigned tutorials and changing the projections and realizing just how not hard this assignment was. I was able to have fun with it, and realize that a colored background wasn’t always the best way to go. I understood things I hadn’t gotten before. Lastly, you can bet getting that map done and turning it in was the best kind of relieving success.

Most of all, I learned the importance of doing your work when you’re assigned it, and crawling before you walk. The struggle to understand a concept may be torture, but once you learn it, you learn it. It helps set you up for the next struggle, with a lot more ease than if you hadn’t survived the prior one.