2013-04-24 49 12

From Geo Hashing
Jump to: navigation, search

Wed 24 Apr 2013 in Regensburg, Germany:
49.0198471, 12.0619058

peeron geohashing.info google osm bing/os kml crox

In a courtyard-like space between residential buildings on Hermann-Köhl-Straße.


... went there in the morning around 10:30, on his way to work. As expected from aerial imagery, the courtyard was accessible from the east via a ramp and a passage; the hashpoint itself was pretty much exactly in the middle, behind a bench among a loose group of trees.

Since the hash was too easy - I cycle through that road almost every day - I decided to at least give you an unusual picture documenting the way there: a non-stop "scan-o-rama" stretching all the way from my home to the hashpoint. The camera (my trusty GoPro) was mounted in a cardboard box on my luggage rack, looking out to the left (and oriented in portrait mode to increase vertical resolution), and recording video at 60fps, while I tried to cycle more slowly than usual.

The video was then reduced to a single column of pixels for each frame, and all those columns concatenated side-by-side, like so:

  • Video to four-pixel-wide strips:
ffmpeg -ss 00:02:10 -i "GOPR2687.MP4" -an -vf "crop=w=1080:h=4:x=0:y=360" -f image2 "part1\strip%08d.png"
  • Rotate strips to vertical columns, and reduce to one pixel width:
for %s in (part1\strip*.png) do @imagemagick-convert -rotate 90 -crop 1x1080+0+0 "%s" "part1s\%~nxs"
  • Concatenate all columns :
imagemagick-montage -mode Concatenate -tile x1 "part1s\*.png" part1assembled.png

(With thanks to my coworker, whose 16 gigabytes of RAM proved necessary to assemble the second part in one go without massaging the swap file for hours - a custom program would've been much more efficient there than imagemagick...)

Effectively, the resulting image has the GoPro's usual stereographic (fisheye-like) projection on the vertical axis, but is projected orthographically (if I cycle in a straight line) or cylindrically (in turns)... with all kinds of wobbles and other artifacts, because I can't really keep my bike vertical and moving at a constant speed all the time.

Anyway, here goes:

Part of the scanorama home to hashpoint
The full image is 30827x720 pixels and about 9 MB
Part of the scanorama from a bakery near the hashpoint to the town center
The full image is 32000x720 pixels and about 8 MB
Part of the scanorama from the town center to dawidi's office
The full image is 32032x720 pixels and about 8 MB

And as far as "regular" photos are concerned: