[Proj] Proj4 cs2cs Program and the Geocentric Coord System

Karney, Charles ckarney at Sarnoff.com
Wed Feb 4 14:32:20 EST 2009

> From: Gerald I. Evenden [geraldi.evenden at gmail.com]
> Sent: Wednesday, February 04, 2009 13:26
> Are we not back to the same business associated with the dead horse issue of
> TM (Transmogrification Meditation): unneeded accuracy and extended
> computational range.

[rest of the rant cut...]


I am willing to stipulate that for many purposes 1m (or 1cm or 1mm)
accuracy suffices.

However, I wish you, in turn, would recognise that there's also a need
for routines which are accurate to round-off and are valid for as wide a
range of inputs as possible.  I deal with complex hardware and software
configurations and tracking down problems in such systems can be
incredibly difficult.  Is the camera calibration wrong because:

    * someone knocked the camera
    * the sensors are out of whack
    * the geographic database is misregistered
    * the wrong vertical datum was used
    * there's a bug in the graphics card
    * the INU is acting up

The list is potentially endless.  It's really, really, useful to be able
to exclude things like

    * the UTM to geographic to UTM conversion is not an identity

I know this attention to detail can seem anal at times.  However, that's
how robust systems are built.  And in my case, people's lives are at

Charles Karney <ckarney at sarnoff.com>
Sarnoff Corporation, Princeton, NJ 08543-5300

URL: http://charles.karney.info
Tel: +1 609 734 2312
Fax: +1 609 734 2662

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