{"id":430,"date":"2020-08-06T14:45:31","date_gmt":"2020-08-06T22:45:31","guid":{"rendered":"http:\/\/blog.geofictician.net\/?p=430"},"modified":"2020-08-06T14:45:31","modified_gmt":"2020-08-06T22:45:31","slug":"round-and-round","status":"publish","type":"post","link":"https:\/\/blog.geofictician.net\/index.php\/2020\/08\/06\/round-and-round\/","title":{"rendered":"Round and round"},"content":{"rendered":"\n

I’m sorry I neglected this blog for the last two months. It wasn’t because I stopped geofiction activities – I just kind of forgot to update anything here. In fact, I’ve been staying busy with various geofiction projects.<\/em><\/p>\n\n\n\n

I ran across a small, free website that someone made that transforms a flat map of an imaginary planet into a globe that you can rotate with the mouse or that can be used to generate a “spinning world” gif. It’s called maptoglobe.com<\/a>.<\/p>\n\n\n\n

I decided I wanted to make one for my planet, Arhet – just out of curiosity. This did have a few minor technical challenges. First, I had to “knit” together the tile images for Arhet. I found a nice utility that does this, an application called tile-stitch by Eric Fischer. It can be found on github<\/a>. Except for one small problem, I just followed the documentation provided on the github README. That one problem: to get it to work in my machine, I needed to modify the code in the stitch.c<\/code> file to include the full path to the geotiff utilities. So…<\/p>\n\n\n\n

Original code:<\/span>...<\/code><\/p>\n\n\n\n

#include <geotiffio.h>
#include <xtiffio.h>
...<\/code><\/p>\n\n\n\n

My version:<\/span>...<\/code><\/p>\n\n\n\n

#include <\/usr\/include\/geotiff\/geotiffio.h>
#include <\/usr\/include\/geotiff\/xtiffio.h>
...<\/code><\/p>\n\n\n\n

Once that was set up, I simply extracted the tiles at zoom level 5 from the Arhet2-carto render using the tile-stitch utility, with this command
.\/stitch -o arhet5.png -- -85.05 -179.99 85.05 179.99 5 https:\/\/tiles01.rent-a-planet.com\/arhet2-carto\/{z}\/{x}\/{y}.png<\/code><\/p>\n\n\n\n

That got the whole planet into a square .png file, which I called <\/span>arhet5.png.<\/code><\/p>\n\n\n\n

The next problem is that the maptoglobe website requires the map image to be in a equirectangular projection. But the tiles for Arhet are in the modified mercator projection used by almost all online “slippy maps,” classified as EPSG:3857.<\/p>\n\n\n\n

So the arhet5.png<\/code> file was in the wrong projection. I found out I could use another utility that I already had, the gdal library, to do this job. I ran the following commands.
\/usr\/bin\/gdal_translate -of Gtiff -co \"tfw=yes\" -a_ullr -20037508.3427892 20036051.9193368 20037508.3427892 -20036051.9193368 -a_srs \"EPSG:3857\" \"arhet5.png\" \"arhet5_tfw.tiff\"

\/usr\/bin\/gdalwarp -s_srs EPSG:3857 -t_srs EPSG:4326 -ts 6400 3200 \"arhet5_tfw.tiff\" \"arhet5.tif\"<\/code><\/p>\n\n\n\n

These produced a .tif file in the right projection, 6400 x 3200 pixels. I then opened this file and resaved as .png again (because this is a more compact format that is therefore uploadable to maptoglobe.com – which has a maximum file size limit).<\/p>\n\n\n\n

I then uploaded that .png file to the maptoglobe site, and it allowed me to save the resulting “globe” – it’s accessible here<\/a>. Further, I was able to make this nice little spinning planet gif:<\/p>\n\n\n\n

\"\"\/<\/figure>\n\n\n\n

That’s the planet Arhet, as it currently stands – note that most of the mapping there is not my own, but the work of the various other Arhet members who have joined me in my experiment.<\/p>\n\n\n\n

That worked out so well that I did the same thing for my own private planet, Rahet (note that the names Arhet<\/em> and Rahet<\/em> are obviously related; Rahet<\/em> came first, and when I decided to change the project and invite other participants, I renamed the old Rahet<\/em> as Arhet<\/em>, and then resurrected the old Rahet<\/em> later and as a separate project again). <\/p>\n\n\n\n

Here<\/a> is a the link for Rahet on the maptoglobe site, and here is the spinning planet gif:<\/p>\n\n\n\n

\"\"\/<\/figure>\n\n\n\n

So those are pretty cool. Remember that the original “slippy maps” (HRATEs) of these two projects are on the map portion of this website, here<\/a> and here<\/a>.<\/p>\n\n\n\n

Music to make HRATEs to: \ud558\uc120\ud638 (Sandy), “Love Me More”<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

I’m sorry I neglected this blog for the last two months. It wasn’t because I stopped geofiction activities – I just kind of forgot to update anything here. In fact, I’ve been staying busy with various geofiction projects. I ran across a small, free website that someone made that transforms a flat map of an … Continue reading Round and round<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-430","post","type-post","status-publish","format-standard","hentry","category-hrate"],"_links":{"self":[{"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/posts\/430","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/comments?post=430"}],"version-history":[{"count":0,"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/posts\/430\/revisions"}],"wp:attachment":[{"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/media?parent=430"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/categories?post=430"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.geofictician.net\/index.php\/wp-json\/wp\/v2\/tags?post=430"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}