From: John Halleck (John.Halleck_at_utah.edu)
Date: Thu Feb 08 2001 - 17:24:08 CET
Received: (from mdom_at_localhost) by karto.ethz.ch (8.9.3/8.9.3/SuSE Linux 8.9.3-0.1) id RAA30870 for cavexml-outgoing; Thu, 8 Feb 2001 17:23:30 +0100 Received: from cor.oz.cc.utah.edu (nahaj_at_cor.oz.cc.utah.edu [155.99.2.2]) by karto.ethz.ch (8.9.3/8.9.3/SuSE Linux 8.9.3-0.1) with ESMTP id RAA30866 for <cavexml_at_cartography.ch>; Thu, 8 Feb 2001 17:23:28 +0100 Received: from localhost (nahaj_at_localhost) by cor.oz.cc.utah.edu (8.9.2/8.9.2) with ESMTP id JAA16257 for <cavexml_at_cartography.ch>; Thu, 8 Feb 2001 09:24:08 -0700 (MST) Date: Thu, 8 Feb 2001 09:24:08 -0700 (MST) From: John Halleck <John.Halleck_at_utah.edu> To: cavexml_at_cartography.ch Subject: Re:Groupings In-Reply-To: <20010208015516.QIQF20154.t21mta01-app.talk21.com_at_t21mtaV-lrs> Message-ID: <Pine.GSO.4.05.10102080911360.15462-100000@cor.oz.cc.utah.edu> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-cavexml_at_karto.baug.ethz.ch Precedence: bulk Reply-To: cavexml_at_cartography.ch
On Thu, 8 Feb 2001 martinl_at_talk21.com wrote:
> Date: Thu, 8 Feb 2001 01:53:28 GMT
> From: martinl_at_talk21.com
> Reply-To: cavexml_at_cartography.ch
> To: cavexml_at_cartography.ch, cavexml_at_cartography.ch
> Subject: Re:Groupings
Minor responces to selected points:
> [...]
> a) While [from to distance bearing inclination]* (where I use the [] to indicate that the order is immaterial when expressed in XML as either as attributes or subelements) must be the most common form of basic recorded data, we have had examples of at least one other form, viz diving data [from to distance bearing depth], which would, I think, also be the format for a levelled survey. There was also that stuff about just using distances - I forget its name...
Level nets are commonly Distance, Azimuth, delta-Z.
Diving data is Distance, Azimuth, Z (from the local surface)
I suspect you are thinking of triangulations or trilateralizations (the later being a
misnomer, since it involves at least four distances in the three dimensional case and
should be quadrelateraliations.). Remembering that triangulations seem to be relatively
common, while the others are not.
> b) If the same survey method applies to a set of readings (eg 'all readings are forward' or 'all readings are leapfrogged') the data could be reduced to [distance bearing inclination]* or [distance bearing depth]*, provided also that the readings are in sequence. The station names are only 'real' for permanently marked stations, otherwise they are convenient but not essential.
I don't thing this accounts for repeated measurements of some value.
I don't see how this accounts for fore and back sights. They
have to be kept separate (Not averaged) to account for magnetic anomolies.
> c) Raw readings may not be available at all either because the surveyors won't release them (as is the case for at least one significant cave in Wales) or because only historic drawn-up surveys exist (maybe a lost cave
> discovered by miners or a cave where access is denied). In these cases, as well as with 'surveying machines' like that used at Wakulla Springs last year the 'raw' data available to be interchanged is likely to be as 3D coordinates: [point E N V]* or [E N V]*. Stations fixed by GPS, radio-loaction etc also come as coordinates in 'standard' instrument surveys.
Nit pick. For real (non-cave) surveys, GPS is treated as raw data
(with published average accuracies, and more exactly availiable variance information.)
So they come as more than just coordinates, they also have other information
useful to an adjustment.
> [...]
Overall, I like your summary to date.
This archive was generated by hypermail 2b30 : Thu Mar 01 2001 - 18:00:00 CET