[Proj] what is wrong with unit Foot?

Gerald I. Evenden geraldi.evenden at gmail.com
Tue Jan 23 14:15:58 EST 2007

On Tuesday 23 January 2007 1:40 pm, Gennady Khokhorin wrote:
> Hello, PROJ!
> Was testing gdalwarp converting images from one coord. system to another
> and found that using WKT in form of esri' .prj file is producing Unknown
> units on result image if .prj contains UNIT["Foot_US", 0.3048]. As a result
> it is interpreted as a meters and output image seats in wrong position.
> Using projections with units Meter is fine.

NOTE: the US foot used in US surveying is: 0.304800609601219m

The 0.3048 value is a "International" foot based upon the exact 2.54 cm/inch

The above may not solve your problems but it is important if one is dealing 
with precise cadastral surveying.  I spent a long time learning this fact 
when first trying to resolve differences in the results of the initial proj 
software and benchmark values many years ago.  :-(

> Command line for the test:
> gdalwarp.exe -rn -co "INTERLEAVE=PIXEL" -co "COMPRESS=LZW" -t_srs
> "ESRI::c:\shared\NAD 1983 StatePlane Alaska 4 FIPS 5004 (Feet).prj"
> -dstnodata 255 i61147a1_utm.tif i61147a1_asp.tif
> Test image i61147a1_utm.tif (36Mb):
> ftp://aerometric-ak:amak2014@ftp.aerometric-ak.com (gok/ImageProcessing
> folder)
> Did somebody experienced the same problem? Is there any work around or it
> is just a bug/limitation?
> Thanks in advance,
> Gennady
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The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939)  British psychologist

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