From: Ralph Hartley (hartley_at_aic.nrl.navy.mil)
Date: Fri Feb 09 2001 - 20:09:24 CET
Received: (from mdom_at_localhost) by karto.ethz.ch (8.9.3/8.9.3/SuSE Linux 8.9.3-0.1) id UAA10664 for cavexml-outgoing; Fri, 9 Feb 2001 20:05:35 +0100 Received: from sun0.aic.nrl.navy.mil (sun0.aic.nrl.navy.mil [132.250.84.10]) by karto.ethz.ch (8.9.3/8.9.3/SuSE Linux 8.9.3-0.1) with ESMTP id UAA10660 for <cavexml_at_cartography.ch>; Fri, 9 Feb 2001 20:05:34 +0100 Received: from aic.nrl.navy.mil (pc31.aic.nrl.navy.mil [132.250.84.181]) by sun0.aic.nrl.navy.mil (8.9.3+Sun/8.9.3) with ESMTP id OAA24601 for <cavexml_at_cartography.ch>; Fri, 9 Feb 2001 14:06:18 -0500 (EST) Message-ID: <3A844064.1010606@aic.nrl.navy.mil> Date: Fri, 09 Feb 2001 14:09:24 -0500 From: Ralph Hartley <hartley_at_aic.nrl.navy.mil> User-Agent: Mozilla/5.0 (X11; U; Linux 2.2.16-22 i686; en-US; m18) Gecko/20010124 X-Accept-Language: en To: cavexml_at_cartography.ch Subject: Re: Other areas that haven't been discussed. References: <Pine.GSO.4.05.10102081723110.5063-100000_at_cor.oz.cc.utah.edu> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-cavexml_at_karto.baug.ethz.ch Precedence: bulk Reply-To: cavexml_at_cartography.ch
One more thing.
It would be good to have an optional "reliability" attribute for any
data. The relation between reliability and resolution would be similar
to that between accuracy and precision.
Possible values for reliability could be "godgiven", "good", "normal",
"bad", and "error", with only the first and last having real meaning.
If a measurement is marked reliability="godgiven" any program should
treat it as fixed, and apply no corrections, adjustments, etc. to it.
Loop closures should consider its variance to be zero. It is the users
responsibility to make sure that there are never errors in data marked
this way, or at least that he wants it to be treated as if it is
absolutely correct. You would use this, for example, to set the
coordinates of the datum to (0,0,0), which by definition is exact. It
should be used very sparingly.
If a measurement is marked reliability="error" then all programs MUST
ignore the measurement, giving the same results regardless of the
measurement's value. A program may include information about the
measurement in summaries, historical information etc. but the actual
value of the measurement must not affect anything else. This is intended
to be applied to measurements that are known to be incorrect.
Setting reliability="error" is much better, from a data safety point of
view, than deleting bad measurements from the file, because it is not so
irreversible.
Programs may, but need not, give more weight to data marked good than to
normal, or to data marked normal than to bad. How this is done, if at
all, is totally at the program's discretion.
Ralph Hartley
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