Monday, 18 August 2014

Just an A

Alberto Cairo's great blog post on the issue of constructive criticism and snark (as in snide remarks) turned into an interesting discussion with some really good contributions. Muggins waded in because I was mentioned in the original post and thought I had some comments to share...including a throwaway line about my first map getting an A+ at University.

And my, didn't the inevitable people enjoy that nugget and wade in with some snark of their own. Curious that because they're the very same people who purport to hate anyone throwing snark in their direction.

Anyway, I've got to hold my hand wasn't an A+ I got, I dug out the work and dammit...just an A. So just for your enjoyment here's the cover of my very first map from University in 1989.

It was an A5 brochure designed to support the Monsters of Rock concerts at Castle Donington near my home town. When opened you got the layout of the concert site and all the important information...such as 'bar' being the first legend item:

The copy I have is getting a little tired and the ink has smudged but the map is still fairly legible. All hand drawn on drawing film with computer generated lettering positioned by hand, symbol design, drawing pen on film etc etc. Lots of work went into this little map.

The back cover had smaller scale location maps:

And here's my lecturer's grade and feedback of which I remain very proud. His name was Roger Anson...a damn fine man and a brilliant lecturer. I was privileged to have learnt cartography from him and his colleagues Mike Childs, Stuart Granshaw and John Robertson.

I've always been particularly proud of his last statement. I always have been someone who tries and helps people do better work. It's why I eventually went into academia and enjoyed helping my own students aspire to be better and to achieve their own goals. It's why I moved to work in the U.S. to help the company I work for make better products to help people make better maps. It's why I take a full and active part in the community with this somewhat snarky blog and a whole load of other far more sensible and unsnarky work.

I also dug this gem out too...not one of my better pieces but I think it was piece of work set to try and create equal looking qualitative shading schemes on an early Mac using just lines. Tough project. Terrible map (by today's standards?)

So there you have it friends...or if you're not a friend and just someone who thinks they know me through my tweets and this blog then maybe we'll get a chance to meet one day and share some constructive ideas.

Sunday, 17 August 2014

LyricMap: Born in the U.S.A.

Number 3 in an occasional series of LyricMaps is loosely based on Bruce Springsteen's Born in the U.S.A.

A hot spot analysis (using Getis-Ord Gi*) in GIS defines statistically significant neighbouring areas that are above or below the global average. Stronger red hot spots define neighbouring areas that have either more or less people born in the U.S.A., compared to the national average. More red (a hot spot) equates to more people born in the U.S.A. and more blue (a cold spot) equates to more people not born in the U.S.A based on data from the 2010 census. Areas shaded in neither blue or red have no statistically significant populations born in the U.S.A. or not so they are similar to the national average.

The counties in New Jersey, Bruce Springsteen’s home state, are all cold spots with more people not born in the U.S.A. unlike Bruce.

Data analysis by Madeleine Parker and Linda Beale. Map by Kenneth Field 

Voronoi treemap maps

The New York Times flexed their considerable graphic muscles this week with some superb interactive charts showing how the population composition of U.S. States has changed over time. You can check them out here.

They really are beautiful graphs. Simple, clean, lots of 'white space', good hierarchy of typeography and excellent use of colour linking to a small map legend. They even provide some additional discussion and as you hover over the graph the intersection between time period and place gives you some basic metrics.

They then added to this excellent set of graphs with an interactive map of the same data; a new kind of map that they're calling a voronoi treemap map.

The data has been pivoted so the focus is on space in contrast to the focus being predominantly on time in the graphical representation. You can pick one of three time slices to explore how patterns vary spatially. The hovers still work extremely well and one click zooms to a state...great user interaction and experience. The benefits of looking at a map instead of the graph are that it should support the visual comparison from place to place. That's not something you can do with the graphs with each one only illustrating a single state...but what about the map?

What fascinated me about the map is the technique. The use of voronoi polygons to sub-divide space into a tesselation of shapes that represent different proportions is nothing new. Treemaps are also nothing new and have been used very successfully as a sort of area-based cartogram. Here, though, NYT have combined the techniques and used a bounding space (each State) inside of which space is tesselated based on the proportion of the population from different other places. It's not something I've seen before and it's always worth looking at experimental cartography.

Does it work?

I like the idea and I like the attempt at trying something new. However, I see two issues that I feel undermine the map and what it offers.

Firstly, the voronoi polygons are only proportional intra-state and not inter-state so you get polygons with the same percentages of populus that are visually quite different to polygons with the same value in another state (see Texas compared to Oklahoma state-born residents, both 61% but one visually dominates). The point about putting anything on a map is to create visual comparisons and the voronois are, effectively, unequal in area from state-to-state so incomparable visually. The relative areas of each state underpin what we see. Since we're visually comparing one place to another and forming a mental picture at first glance Texas would seem to have a larger number of State-born residents than Oklahoma. I'm not sure there's an easy solution unless you turn the voronois into a population-equalizing cartogram (e.g. the Gastner Newman) to account for the different sized areas. It'd certainly be interesting to see what happens if they were equalised by population or area.

My second observation is really just about the design and layout. In each state the surrounding voronoi fragments seem to be randomly positioned around the central voronoi polygon that represents the people born in-state. If you look at the small legend map on the graph version you see that the orange, green, blue and pink colours are used to suggest west, south-west, north and north-east. It would have been nice if the surrounding voronois were arranged so they sit on a compass direction to where the state actually exists. So for each state the oranges would always be on the left, the blues to the north etc. This may bring some sense of structure to the map and avoid the somewhat random positioning we currently see.

Overall I think there's a lot of merit in this new map technique but it probably needs some more thinking to make it really useful.

Thursday, 14 August 2014

Web Mercator and Comparisons II

[this post has been updated]

Not a week has gone by since I posted about the problems of comparing areas between places using Web Mercator. Here's a 'simple map' (author's phrase) that allows you to compare Gaza with other places on the globe. The interactive version is here [map now corrected].

Terrific idea...take the outline of Gaza and allow people to enter a place they are familiar with in order to better understand the size of the place in comparison with somewhere they know.

Except the basemap is Google's Web Mercator (other Web Mercator basemaps do exist) and the shape has been drawn across the map. 

Only places directly on the equator contain no areal distortion on Web Mercator. Gaza lies at approximately 30 degrees North so there's already considerable distortion in the area of Gaza on Web Mercator.

If you then pan and zoom the map, the Gaza shape remains the same size and shape (at each scale) wherever you go to on the globe. It does not get reprojected as you move across the map and that's a huge cartofail fail regardless of the projection. As we saw in my previous post by looking at Tissot's Indicatrix the size of areas gets massively distorted across Web Mercator. The shape of Gaza would be no different.

Unfortunately this is not accounted for in this map. A classic case of ignoring the impact of map projections. Unless you compare Gaza with somewhere else that is exactly 30 degrees North (or South) then you're comparing one distortion with another and the relative scales of the overlay graphic and the basemap are out of sync with one another. The map, then, is utterly useless and, worse, people look at it and believe that it accurately portrays the stated aim. It doesn't.

A lot of people say to me that the science of cartography has little relevance anymore and it's all about form over function, or function over form and that rapid hackups that buck cartographic convention are healthy. If those that (a) build this sort of cartofail and (b) those that unwittingly consume it are happy then there's no hope. Unfortunately experience shows people tend to be happy in their ignorance and prefer their own facts over fact itself. If you make maps, learn some's really not that difficult but no amount of clever coding allows you to ignore the basic science of the very thing you're coding. Use your coding skills wisely and learn some domain knowledge to give those skills real power and substance.

ht to Ryan Cooper for alerting me to this map and for correctly identifying the problem.

UPDATE: Something unexpected happened after Ryan Cooper, Ralph Straumann and I tweeted and blogged about the problems of this map. The author Ahmad Nassri got in touch. I was primed for the usual volley of abuse but unlike the majority of people who seem to take offence at having a critique of their work plastered online pointing out major faults, Ahmad took the opposite view. An online conversation took place in which he was grateful for someone identifying a shortcoming and eager to learn of the cartographic 'problem', he sought help in figuring out a way to overcome it. His reaction was refreshing and a credit to his desire to get his work 'right'. Within a couple of hours he had figured out a way to control the shape of Gaza using the Google Maps API geodesic parameter so that it would draw geodesically as you pan and zoom around the globe. It doesn't get over the problems of Web Mercator but it does make his Gaza shape scaleable across the globe to work in sync with the projection. Both the map and the shape of Gaza are now distorted in the same way which is as much as can be hoped for if Web Mercator is the basemap. The map now does what it claims, it gives people the correct basis for visual comparison but most of all Ahmad illustrated a willingness to take on board our comments and correct his work. He should be hugely commended for his reaction. Win win!