Posts Tagged ‘bad projection

14
Aug
09

Way Over in British Columbia

Today’s effort comes to us from Kerr Wood Leidal, a consulting firm in Canada:

Detail of map - click for full poster. Taken from http://kwl.bc.ca/docs/CEBC2008-RHAM-FinalAwardofMerit.pdf.

Detail of map - click for full poster. Taken from http://kwl.bc.ca/docs/CEBC2008-RHAM-FinalAwardofMerit.pdf.

This one was brought to my attention by a reader, Eliana, who appeared particularly exasperated that this map won an award. It seems that the folks at KWL took first prize in the 2009 Map Gallery competition at GeoTec, which bills itself as the largest GIS conference in Canada. According to the GeoTec site, the winners were selected “based on overall appearance and effectiveness as maps.” So, this means they have to a) look good, and b) communicate spatial information clearly. Longtime readers may recall that one of these things is more important than the other. Though this is not to say that making your map look good is unnecessary, and in a competition like this, it’s a fair criterion for judging.

Let’s start at the legend – of the 8200 or so red spots on this map, each one encodes how much hydropower could feasibly be generated at that site. A red dot means < 1 megawatt, a red square is 1 – 10 megawatts, and a red triangle is > 10 megawatts. This is a non-orderable scheme – squares, circles, and triangles cannot be put into an inherent order. So, it doesn’t make sense to use different shapes for different numbers of megawatts — which can be put into order. Dots of different size or perhaps color brightness (but the same color hue – so, for example, a scheme from light blue to dark blue) would be more sensible here.

The other big problem with this scheme is that if you look at the map, you can’t pick out the squares from the circles from the triangles in most areas. They’re way too small to be able to tell which shape is which without staring or zooming way in, and even then it’s sometimes ambiguous. I will add the caveat that I don’t know how large this map was printed – it may be less of a problem if this thing is two or three feet across. And I’m not even sure if this map really needs to go into this much detail. It does a good job as it stands of showing the general distribution of hydropower sites, mostly clustered along the west of the province. If the authors want to add an extra level of information, about how much power might be generated at each site, their task becomes much harder, because now the dots have to be separate enough, and big enough, for people to be able to tell how they vary. And the reader cannot effectively do that, here.

Even if you could visually tell one shape from another, however, it would still be difficult to pick out the overall pattern of where the 1 megawatt sites are, and where the 10 megawatt sites are. Shape, as a visual means of encoding information, is weak in terms of what we call selectivity. It’s hard to select just one shape, and then try and find the distribution of only that shape. It’s much easier to do this sort of task with something like size – you can quickly see where the big dots are clustered and where the small ones are. A quick example:

Selectivity Diagram

Notice how easier it is to pick out the cluster of small squares near the center than it is to pick out the cluster of triangles near the center - size has better selectivity than shape.

Moving on from the dots, let’s consider a few other, lesser offenses. The labeling has poor contrast with the background, especially at Stewart and Port Hardy. Interestingly, some of the labels have been set in light-colored type, to better stand out against the water, thus demonstrating that the labeler was mindful of contrast issues. But not enough to make them legible against a mass of little red shapes.

Notice the white area in the northwest. That’s part of Alaska. It looks like it’s buried under an ice cap or something, given the color scheme and the fact that it’s flat, while the rest of the map shows terrain relief. I’ve never been to Alaska, so I suppose it could in fact bear a great resemblance to Antarctica. More of concern to me is the fact that the authors have possibly done one worse than the dreaded island effect. Instead of either showing British Columbia as an island with no surrounding land, or showing it in its geographic context, with the USA and other provinces around, the authors have chosen to include just one part of one of the surrounding areas. It looks very odd, and I think it would look better showing just the province, really.

Speaking of odd, it looks like someone has discovered the joy of the “glow” effect in the Adobe suite of graphic tools, because the entire coast of British Columbia is glowing white. Now, a glow effect can be a great addition to a map, but it would probably make more sense to do one a light blue one that looks like shallow coastal water, rather than giving the appearance that there’s been some sort of radioactive disaster off the Canadian Pacific coast.

Since this is a map about hydropower based on the flow of rivers, where are the rivers on this map? You can see a few here and there, in a very light blue, but the hydrography should really stand out more. Maybe not every single creek, but at least the major ones.

Finally, a note on the map projection. The authors appear to have kept the central meridian for this conic projection somewhere far east of the map area – say, around the center of Canada.  For those readers who may be confused by what I just said, I will avoid giving an entire lesson on map projections. Instead, here’s a somewhat related way of thinking about it: Consider your average map of Canada, grabbed randomly from the Internet – the kind with the curved appearance to it. Doesn’t it look like the authors of the map above took BC from the far west end of one of these typical Canada maps, and didn’t bother to rotate it so that it wasn’t tilted clockwise anymore? If it’s the only thing on the map, BC should be centered so that it’s northern border has a shallow “U” shape, instead of curving downward only. The projection on this map just constantly reminds me of the fact that BC is at the far west end of Canada.  Perhaps the authors wanted to keep that suggestion in my mind – “British Columbia: We’re way over here!” Might make a good provincial motto.

One Nice Thing: The terrain relief is not just a useless bit of decoration – it’s useful, because hydropower potential is affected by terrain. You can see the river valleys and everything (if not the actual rivers, unfortunately). So, the relief here is both a nice aesthetic component, and conveys information relevant to the topic at hand. A win-win.

Before I leave off, I’d like to thank all of you who have been writing in to me and submitting maps you have encountered. It’s a big help to have other eyes looking for these things. I may not end up using every submission, but I appreciate them nonetheless.

05
Jul
09

They’re Watching Us

Today’s effort comes from Privacy International, a human rights watchdog…

2007 Surveillance States

Found at http://www.privacyinternational.org. No author given.

Two words: Mercator Projection.

See, back in the 16th century, this guy invented a map projection that helped make it easy to navigate at sea. And, if you happen to be making a nautical chart of the North Sea, this is probably a good projection to use. If you’re making a map of roughly anything else*, it’s a terrible choice (though this doesn’t stop Google Maps from using it). It distorts sizes greatly as you move away from the equator. See Brazil? Brazil is four times larger than Greenland, in reality. On a Mercator, Greenland looks like it could eat Brazil. There are also political arguments against using it as well, on account of the fact that it makes Europe and North America look larger, relative to Africa and South America, than they really are. Anyway, point being, there are many other better options for a simple world thematic map.

*Yes, there are a few legitimate uses for Mercator, but this is definitely not one of them.

Colors: Looking for countries that fit in the first three categories (“Consistently upholds human rights” / “Significant protections and safeguards” / “Adequate safeguards against abuse”)? They’re not on this map. Sorry, thanks for playing along with our legend! What there is, though, is Greece. Which is shaded a color that doesn’t actually appear in the legend. If you click on the picture you can see the table with the scores each country was given, and it’s clear there that Greece was supposed to be in the third-lowest category.

When you’re ranking countries according to a particular data set, such as how surveillance-y they are, you want to use colors that are likewise ranked, to visually show that these places can be ordered from most to least. Look quickly at North and South America and tell me, between Canada, Brazil, and the US, which is worse? It’s pretty hard to see any sort of natural arrangement there. Brazil is in red. Red is danger, right? But maybe the black indicates the dark and insidious police state that is the US. My favorite, though, is the bright magenta in places like France and India. What’s a good color to use that indicates that something is worse than red-level, but not as bad as black-level surveillance? That is the answer that someone came up with. Today’s surveillance alert level is bright magenta.

Also, I’m being a bit generous in interpretation, because the magenta in the legend doesn’t match the magenta on the map. The reds don’t really match, either. So, if you’re keeping score at home, a total of two out of the seven colors in the legend actually appear on the map. And I didn’t check the yellow that closely.

Grey probably means no data. But it’s probably dangerous to make assumptions about what colors mean on this map.

One nice thing: The colors are set such that the worst offenders, in black, are one of the things that stand out the most. Though, they are tied visually with the fourth-worst offenders, in yellow.

(Someone here in my lab disagrees with me on the above – given that there is a visual tie, the black doesn’t stand out sufficiently)

One alternate nice thing: It’s nice that there are insets to help clarify cramped regions.

30
Jun
09

The Cruelty of War

Another Wikipedia map (don’t worry, they won’t all be from there), showing battles of the American Civil War, based on National Park Service data:

Amazingly enough, it turns out that the red-coded counties, coded for “Eastern Theater,” are, in fact all in the east! The color coding has no particular use here, except to show you the difference between the NPS-defined theaters of the war. Why not just draw a border around the zones, so that you don’t need a confusing rainbow of colors to tell you roughly nothing that isn’t apparent by looking at where the filled-in counties are?

Also, why is “Mult. Years” the darkest color? This map’s color scheme suggests that “darker is later” – 1863 is darker than 1861. Making a county that saw battles in multiple years (about half of the ones on the map) even darker than the color for 1865 makes it seem like they were fighting the war there well into the 1870s. A media conspiracy has kept it secret.

Quick tip: Let’s say you’re making a map of something that happened, say, 140+ years ago. Using modern county and state borders might be ill-advised.

It looks like the US is tilted backwards. Maybe it’s a commentary by the author – “Look! The US is falling over…a house divided cannot stand!” Actually, what probably happened is they used a sinusoidal projection, which is good for showing the whole world at times, but not so good for showing one country at high latitudes.

One Nice Thing: The color scheme for the years within each theater makes some level of sense – the colors are arranged in a light-to-dark pattern as the years go on. Excepting, of course, the color for “Mult. Years.” Good cartographic sense.




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