[postgis-users] Followup: AsSVG and precision control

Andreas Neumann neumann at karto.baug.ethz.ch
Thu Jan 13 05:56:52 PST 2005


I would like to continue the thread between Klaus and strk from October 


Klaus wrote a patch (http://svg.cc/pg/assvg/assvg-0.5.1.patch) that 
allows better precision control than the version distributed with the 
official postgis distribution.

 From what I read in the thread I have the impression that strk maybe 
misunderstood the intention from Klaus.

With Klaus' patch one can specifically set the nr of decimal places (the 
places after the decimal point) to say 1, while with the old version 
distributed with Postgis one cannot specifically control the decimal 
places, but only the overall number of digits including the decimal 
places. I think Klaus patch is more elegant and should be made the 
default version in Postgis.

To illustrate the problem with the old solution:

say the coordinate range in your project varies from 500 to 500000, in 
AsSvg you specify that you want 8 digits, than the coordinates with 500 
will have more decimal places (5 decimal places, more accurate) than the 
coordinates with say 400000 (2 decimal places, less accurate), which 
means, that you have a varying accuracy over the whole project. I don't 
think that this is the behaviour that the Postgis/SVG users want.

So, please, if possible, if you could make Klaus patch 
(http://svg.cc/pg/assvg/assvg-0.5.1.patch) the default AsSVG function in 
the official Postgis distribution, that would really help.

Thanks for your help!


Andreas Neumann - Department of Cartography 
Swiss Federal Institute of Technology (ETH) 
ETH Hoenggerberg, CH-8093  Zurich, Switzerland 
Phone: ++41-1-633 3031, Fax: ++41-1-633 1153 
e-mail: neumann at karto.baug.ethz.ch 
www: http://www.karto.ethz.ch/neumann/ 
SVG.Open: http://www.svgopen.org/ 
Carto.net: http://www.carto.net/

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