At 10:08 10-02-03 -0700, P A Hill & E V Goodall wrote:
>Peter MATTHEWS wrote:
>>Final Data - Corrected and Uncorrected
>>==========
>>The input data which is currently the accepted final version of
>>individual Shots or other measured data: Final Corrected if systematic
>>instrument corrections have also been applied, Final Uncorrected if
>>systematic instrument corrections exist but have not yet been applied.
>>Comments:
>>1. This data is approved as now suitable for data reduction, but may or
>>may not be ready for input to any particular survey reduction program
>>depending on the program and what it can accept as input data.
>
>We are half way through a list of possible classes of things we might say
>about a data set and the current classification is called final? I still
>don't get this. What is 'final' about it? The concept as defined makes
>sense, the choice of terms doesn't.
The list of terms we are considering actually covers more than one data set, and spans between the various measurements taken in the field and the subsequently calculated co-ordinate data which will be used in drafting the map. The term "final" is referring to the final accepted version of one of the data sets, namely - the "field" data set which will form the input data to the data reduction program which will produce the co-ordinate data. It is the final agreed version of the measurements taken in the field. However if there is a more suitable concise term to describe this final version then we could certainly use that instead.
> > Final Corrected if systematic
> > instrument corrections have also been applied, Final Uncorrected if
> > systematic instrument corrections exist but have not yet been applied.
> > Comments:
> > 1. This data is approved as now suitable for data reduction, but may or
> > may not be ready for input to any particular survey reduction program
> > depending on the program and what it can accept as input data.
>
>You left out this combination in the above definition: What do you call
>data that has been declared as the official approved numbers when no
>instrument corrections exist? Would this be called simply "final".
Good point Paul - I overlooked spelling out this option. Yes, I had assumed it would just be called "Final" - the terms "corrected" and "uncorrected" were qualifiers to use if/when necessary. But now that you have flagged up the issue, maybe it would be helpful if we were more specific about the two uncorrected states so that there is no doubt left. There are probably better terms to use, but how about the following meanings for the qualifiers:
Corrected:
Systematic instrument corrections were recorded and have already been
applied to the measurements in the data set.
Uncorrected:
Systematic instrument corrections were recorded but have not been applied
to the measurements in the data set.
No Corrections:
No systematic instrument corrections were recorded.
>Is the idea that when I have finished editing I should call the data
>"final", lets say this is set A. If I then go on to mess with the data to
>close the loops, so now in addition to data in set A, I have data in set
>B, therefore I need to now label Set A as "final uncorrected" and set B as
>"final corrected" in order to differentiate the two.
No, the "correction" terms refer to the application of systematic instrument corrections, not to the adjustment of the data in order to close any loops. These are two separate issues. The term "adjusted" will later be addressing the loop closure issue. Modifications to leg data to make a loop close are not actually corrections, but statistical adjustments.
>Your Leg Data definition suffers from the same problem of data in three
>states, but do you really want three possible choices or just two?
>You have two possible states if you drop the words "exist but" from both
>definitions.
Yes, Leg Data would also need the three "correction" qualifiers similarly to Final Data above.
Taking the above points into account, here are suggested revised definions:
Leg Data - Corrected, Uncorrected, No Corrections
>>Leg Data - Corrected and Uncorrected
>>========
>>Final Data which provides only a single set of the necessary Measurements
>>for each Leg, possibly by consolidation of several sets of final Shot
>>data: Leg Corrected if systematic instrument corrections have also been
>>applied, Leg Uncorrected if systematic instrument corrections exist but
>>have not yet been applied.
>
>What is a leg? Is this the right term used by land surveyors?
>Is a leg a set of shots between intersections? In a simple linear cave
>can I have two or more legs? Is there an order to legs required by
>CaveXML or does that come later or as a refinement or attribute of a leg?
My understanding of a leg is the survey line joining two adjacent survey stations, with the leg measurements being used to calculate the position of a survey station based on the known position of the previous adjacent station in the traverse line.
In the draft definitions on the CaveXML web pages I have suggested that we use the term "shot" for each sighting between two stations where there have been multiple sightings between them, and "leg" to distinguish any final single set of readings between the two stations which may have been arrived at by averaging the measurements in a set of shots between the stations. These "leg" measurements could then be used to make the calculation of the new station's position. Of course an alternative situation could be that a particular data reduction program takes in all the shots between the two stations, calculates a set of new positions based on each, then presents an averaged new position. In this situation, "legs" would not enter the picture. So, "leg" is an optional term to be used when needed. Where only one shot is taken between two stations, then the leg and shot are obviously the same thing.
>-Paul
Peter Received on Thu Feb 13 04:20:25 2003
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