Best way to deal with overlapping elements

[Azélor]

I was wondering if there was a better way to deal with overlapping categories on thematic maps.

In my example below, I have a map showing the evolution of the tundra biome merging 3 different maps. One is the actual climate of the world representing the average between 1976 and 2000. The other 2 are projections made for 2100 using 2 scenarios. I chose to keep only the extreme ones to show the difference (A1FI and B1). I'm trying to show where the tundra would expand and recede by comparing the 2 scenarios to the present era.

I was wondering if it was easy to understand and if there is a better way to do it. Note that the expanding tundra come from the melting ice sheet of Greenland, otherwise, it's just receding everywhere. In the optimist scenario, Tibet lose almost 70% of it's tundra.

tundra.jpg

[Chick]

It's understandable, but I wouldn't say easy. Perhaps you could use different colors instead of hatch lines, warm colors for expanding, cold blues for shrinking, or something like that?

[Hai-Etlik]

Well, the projection you've used is really inappropriate. Albers Conic Equal Area would be a better choice to cover northern Canada and Greenland in a map where area is significant.

If you really want to show everything in one map, then using different colours, with a patterned blend for "gained then lost" (which thankfully doesn't happen in this data set) is probably the best way to go. Go to ColourBrewer and pick a 5 class diverging scheme.


I was able to toss this together in QGIS fairly quickly

NA-Tundra.png

Layout was fairly slapped together.

[Azélor]

I know, this was the Robinson projection but this is just a sample. The map covers the whole planet.

QGIS looks interesting for real world data. Does it have a steep learning curve ?

[Hai-Etlik]

I know, this was the Robinson projection but this is just a sample. The map covers the whole planet.

QGIS looks interesting for real world data. Does it have a steep learning curve ?

It's a decidedly different way of dealing with things from graphics software but as GIS software goes it's fairly approachable. I have an incomplete and now somewhat dated tutorial on the very basics of QGIS here: http://www.cartographersguild.com/sh...ad.php?t=17469

I don't think I ever covered any of the Geoprocessing I used in building this map (generating differences between the layers) or how to create a custom projection.