Printing a wall-sized world map and what I've learned from it • Hacker News Board

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

#81

Post by tomgp » Thu, Apr 30, 2015, 3:14 PM UTC

UnoriginalGuy wrote: post #30

dietrichepp wrote: post #7

This guy "loves world maps" but chose Mercator for the wall of his room? I guess there's no accounting for taste. There are hundreds of projections to choose from, why choose the one optimized for navigation by compass ?

He only had a Mercator map source data. Unless you know how to switch Google Maps into Peters Projection mode? I am surprised people who read the article are even asking this considering how much he struggled even to get the source image (and how he ultimately wound up manually stitching together print screens).

Jason Davies has done excellent work on addressing this problem in the browser https://www.jasondavies.com/maps/raster/

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

#82

Post by kens » Thu, Apr 30, 2015, 3:15 PM UTC

I can't believe how negative the comments are here, criticizing the projection. I don't really like the term "middlebrow dismissal" but it seems to apply.

As an aside, have you looked closely at Greenland on a globe? It looks all wrong - long and skinny like someone messed up the aspect ratio.

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

#83

Post by jkot » Thu, Apr 30, 2015, 3:22 PM UTC

I printed 4x1.2m night sky panorama for my living room. I worked on Skyview fork (astronomical image stitching library), after some processing I got 5GB JPEG with 60K to 20K resolution. 6 hours of work and 80 euro printing fee.

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

#84

Post by mewo2 » Thu, Apr 30, 2015, 3:25 PM UTC

Retric wrote: post #76

mewo2 wrote: post #63

Earlier quoted context omitted.

Yes, absolutely! The Mercator projection isn't the only conformal projection, but it is the only one for which north-south maps to the vertical axis, and east-west to the horizontal axis. That means that it maps the whole world onto a rectangle, which works well both for computers and interior decorating. As for other rectangular projections, the most common is the equirectangular (or plate carrée), which simply maps…

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 the other way around.

I'm also not aware of any of the main online maps changing projection as you zoom. It seems like that would be more pain than it's worth.

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

#85

Post by quinndupont » Thu, Apr 30, 2015, 3:27 PM UTC

This is so brilliantly reminiscent of Borges' famous fiction:

On Exactitude in Science Jorge Luis Borges, Collected Fictions, translated by Andrew Hurley. ...In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the Empire, the entirety of a Province. In time, those Unconscionable Maps no longer satisfied, and the Cartographers Guilds struck a Map of the Empire whose size was that of the Empire, and which coincided point for point with it. The following Generations, who were not so fond of the Study of Cartography as their Forebears had been, saw that that vast Map was Useless, and not without some Pitilessness was it, that they delivered it up to the Inclemencies of Sun and Winters. In the Deserts of the West, still today, there are Tattered Ruins of that Map, inhabited by Animals and Beggars; in all the Land there is no other Relic of the Disciplines of Geography. —Suarez Miranda,Viajes de varones prudentes, Libro IV,Cap. XLV, Lerida, 1658

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

#86

Post by brotoss » Thu, Apr 30, 2015, 3:28 PM UTC

Or you can just buy this big ass one from Ikea for 129 bucks:

http://www.ikea.com/us/en/catalog/products/70119430/

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

#87

Post by stefap2 » Thu, Apr 30, 2015, 3:29 PM UTC

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?

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

#88

Post by stefap2 » Thu, Apr 30, 2015, 3:30 PM UTC

brotoss wrote: post #86

Or you can just buy this big ass one from Ikea for 129 bucks: http://www.ikea.com/us/en/catalog/products/70119430/

Doesn't have small villages.

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

#89

Post by cousin_it » Thu, Apr 30, 2015, 3:31 PM UTC

mewo2 wrote: post #34

dietrichepp wrote: post #7

This guy "loves world maps" but chose Mercator for the wall of his room? I guess there's no accounting for taste. There are hundreds of projections to choose from, why choose the one optimized for navigation by compass ?

I can't believe I'm doing this, but I think I'm going to defend Mercator here. The Mercator projection was indeed originally designed for compass navigation, but the reason it's still used for web mapping is slightly different. The Mercator projection is conformal . What this means is that angles (and hence in some sense shapes) are preserved locally. When we zoom in on a small section of the Mercator projection, we…

If I understand correctly, Mercator is the only conformal projection where north is always up, no matter where you zoom in. That makes it nice for online maps. If you relax the "north is up" requirement, there's tons of conformal projections that look nice: http://www.progonos.com/furuti/MapProj/Normal/ProjConf/projC...

I really like the "classic Guyou" projection: http://www.progonos.com/furuti/MapProj/Normal/ProjConf/Img/Z.... It mangles the ocean pretty badly, but the sizes and shapes of the landmasses are surprisingly realistic, and it's rectangular to boot.

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

#90

Post by Mtinie » Thu, Apr 30, 2015, 3:31 PM UTC

Doctor_Fegg wrote: post #15

"OpenStreetMap... the additional work to custom style the maps would be extraordinary" It absolutely wouldn't. Download TileMill or its successor, Mapbox Studio. Adjust the (Carto)CSS. Done. Though for a map of this scale I'd probably work straight from Natural Earth[1] without involving OSM, to be honest. Looks great, anyway. [1] http://www.naturalearthdata.com/

I'll be honest, I never really gave a lot of thought to whether or not I'm a "map lover" until this HN topic appeared in my feed, but your comment hooked me in...

...so much for this morning's priorities. /sigh

If you're familiar with the Natural Earth data set, do you know if it is possible to apply a transformation so a map could be printed of the World using the Cahill or Waterman projection?

I can envision a striking large-scale art piece that started from a "butterfly" representation of the World.