[OSM-talk] Contours server (was: Re: ski pistes)

[Steve Hill]

Just a quick follow-up with some numbers for disk space usage for those 
interested.  I had a go at importing 10 metre contour lines for the whole 
of Eurasia into PostGIS - latitudes of 0 - 46 degrees North required about 
110 gig of disk space for the Postgres table and amounted to around 105 
million contour lines.  (I stopped it at this point before I ran out of 
space :) - the SRTM3 data set extends up to 60 degrees North).

0-46N across Eurasia amounts to 3244 1x1 degree tiles.  So this averages 
you around 35MB of disk space to import a 1x1 degree tile into PostGIS 
(obviously dependent on the terrain the tile covers), giving rough 
estimated numbers of:

  * Africa:	111 GB	(3250 tiles)
  * Australia:	36 GB	(1060 tiles)
  * Eurasia:	202 GB	(5902 tiles)
  * Islands:	5 GB	(141 tiles)
  * N America:	82 GB	(2412 tiles)
  * S America:	62 GB	(1807 tiles)
  * WHOLE WORLD:	498 GB	(14572 tiles)

So with half a terabyte of disk you can import the whole lot...  There is 
also the higher resolution SRTM1 data set covering North America - I'm not 
clear on how using those data would affect these numbers - probably not 
much since you'll probably have roughly the same number of contour lines, 
they will just be positioned more accurately.

  - Steve
    xmpp:steve at nexusuk.org   sip:steve at nexusuk.org   http://www.nexusuk.org/

      Servatis a periculum, servatis a maleficum - Whisper, Evanescence