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Printing a wall-sized world map and what I've learned from it

dominik-schwarz.net

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Re: Printing a wall-sized world map and what I've learned from it

#91

Post by rcknr »

brazzy wrote: post #78
rcknr wrote: post #73

Notes about projection choice seem to prevail, which is nerdy. Well, 400 euros for a wall map seems like a lot of money, but what isn't described very well is how the source file was created. It seems like the guy was manually stitching screenshots. God knows how much time did this take. There's little to no hacking in this project. Just the bit where he makes something custom.

I'm pretty sure the costs were not a running tally, i.e. they need to be added up for a total of over 1140 EUR.

I was also confused about that. Just assumed he incremented expenses with each step, but I think you're right, since 10 euros for framing doesn't sound legit. At over thousand of material/services cost the whole thing appears to be even less sensible.

Re: Printing a wall-sized world map and what I've learned from it

#93

Post by maxerickson »

stefap2 wrote: post #87

Since it was stitched using a number of smaller images printed from Google maps, wouldn't you end up with a bunch of "google-maps" watermarks all over the map?

The watermark is per screen, so you just have to crop off the watermarks (and account for the cropping as you set the view for each screenshot).

Re: Printing a wall-sized world map and what I've learned from it

#94

Post by logfromblammo »

castell wrote: post #19
xt wrote: post #5

Very cool. But I was surprised to see he chose Mercator. See: https://xkcd.com/977/

I thought that too. http://en.wikipedia.org/wiki/Mercator_projection Which map projections would you choose? A difficult decision: http://en.wikipedia.org/wiki/List_of_map_projections

If you have to do it yourself anyway, why not make your own projection? I'd do a Dymaxion-style projection onto a truncated icosahedron (Goldberg polyhedron G(1,1), a.k.a. the soccer ball shape), with the poles centered in two of the pentagons, and as many edges as possible over bodies of water. Then I'd print each tile image and plaster it to its own mounting board, trimming the backs of the board edges to 69 degrees on all the hexagons and 73.5 degrees on all the pentagons. At that point, I'd permanently join the tiles with appropriate amounts of contiguous land mass, using brackets, and attach magnets to the remaining edges in such a way that you could assemble them like a puzzle.

I'd rather have a gigantic globe (that can also be dismantled for moving or storage) than have a wall map.

Re: Printing a wall-sized world map and what I've learned from it

#95

Post by Retric »

mewo2 wrote: post #84
Retric wrote: post #76

Earlier quoted context omitted.

Gall-Peters is also a conformation projection that maps north-south maps to the vertical axis, and east-west to the horizontal axis. As to online maps one major advantage is the X-Y scale does not get nearly as messed up at multiple zoom levels. However, online maps alter the projection as you zoom so this is not much of an issue.

Gall-Peters is definitely not conformal. It preserves area, but greatly distorts angles, apart from at the two standard parallels of 45 degrees north and south. This results in the shapes of land masses getting very squished towards the poles (and to a lesser extent, the equator). For an example, look at the shape of Greenland, which appears twice as wide (east-west) as it is tall (north-south), when in reality it's…

A Mercator projection (ed: is a Conformal map, but) it also greatly distorts both angles and shapes as you approach the poles. The trivial example is to walk a square mile (N,W,S,E) you would expect the opposite sides to be at 45deg angle, but on Mercator the sides get stretched so a square in the real world can have a 10+:1 or even 100:1 side lengths on a Mercator map.

The property they both preserve is points north, south, east, or west of them on a globe are also north, south, east, or west of them in the projection. (Plenty of rectangular projections don't have this property ex: http://geographer-at-large.blogspot.com/2011/08/fun-with-map...)

The issue is interior angels of a triangle on a sphere don't add up to 180 degrees so you literally can't preserve all angles on a projection.

PS: If you actually walk exactly 1 mile north, 1 mile west, 1 mile south, then 1 mile east you don't necessarily end up on exactly the same place on a globe. (It does work if you start half a mile below the equator.)

Edit: Not that the earth is even a sphere...

Re: Printing a wall-sized world map and what I've learned from it

#97

Post by derefr »

zongitsrinzler wrote: post #40

I used to do this all the time in the military. We would glue together and laminate smaller maps into one big map (That was then used in a control point for real time planning).

I was about to say—isn't this sort of thing (fine-granularity topographic surveying/GIS) exactly what the Professional version of Google Earth is for, marketed to governments/militaries/etc.?

Re: Printing a wall-sized world map and what I've learned from it

#98

Post by maxerickson »

imaginenore wrote: post #47
zokier wrote: post #6

Earlier quoted context omitted.

I thought that too, but on the other hand it is not readily apparent where you'd get a good non-mercator map raster.

You can just generate one from OpenStreetMaps

How would you approach it? Setting up a renderer with global coverage isn't really a trivial task. It is straightforward, and there are reasonable guides, like https://switch2osm.org/ , but the planet database is just a big database to work with.

(I think I would take advantage of Mapbox's free plan, which allows for 1 custom stylesheet and enough usage to get the image together. I guess there are lots of people who would be happy to render a stylesheet (especially if a modest fee is involved), but I'm not sure how someone on the street figures that out and gets in contact with them)

Re: Printing a wall-sized world map and what I've learned from it

#100

Post by vilhelm_s »

My dad has a more low-tech approach: he buys a bunch of maps from the National Land Survey, cuts away the margins with scissors, and tapes them together with scotch tape. Rather than world maps, he likes large-scale maps of particular locations.

It's really very cool to a have that kind of wall-scale high-resolution information display. When I get a more permanent place to live, I'm tempted to do the same thing.

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