Discussion of FieldGenius related issues and questions.

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Postby Richard Sands » Tue Jul 15, 2008 2:46 pm

What information gets re-coordinated when we invoke a Re-cordinate.
I ask this for both FG2008 & MSCAD2008.
Referring to changes made to instrument/ target heights, measured or input distances, bearing changes.
Do Resections, Manual traversing from surveyed (sideshots) point, Cogo calculations from surveyed points,two line intersections - anything that uses surveyed points from which to calculate new points.
I would not expect any changes to manually stored points (enter NEZ).
Maybe it would be easier to know what DOESN'T get changed in the process.
Richard Sands
Posts: 424
Joined: Mon Feb 14, 2005 1:10 pm
Location: Tasmania

re-cordinate raw data

Postby Richard Sands » Thu Jul 17, 2008 2:53 am

This process has the potential to be a real nightmare, - a recipe for data disaster.
from the FG manual
After you have made your changes you can re-coordinate the raw file so the
changes are displayed on the screen and saved in the project database.
When you re-coordinate the raw file it will process the whole file from
beginning to end. This means if you have changed the coordinate information
for a point there is a chance that it will be changed back to its original value if it
was measured and recorded in the raw file.

It appears this doesn't work in certain areas where data is calculated from measured points. Therefore some points get re-cordinated and some that should dont.
I suggest an insert in the Manual giving more specific details and appropriate cautions would be a welcome addition please.
Richard Sands
Posts: 424
Joined: Mon Feb 14, 2005 1:10 pm
Location: Tasmania

Postby Jason Poitras » Thu Jul 17, 2008 7:34 am

Hi Richard,

Everything gets processed, that's the summary of what happens. Every record in the raw file that creates a coordinate will be processed. Coordinates can be created from store points, calculated points, imported points, total station measurements and GPS measurements.

This applies to MSCAD and FieldGenius.
Jason Poitras
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Re-cordiante Raw Data

Postby Richard Sands » Thu Jul 17, 2008 12:52 pm

Thanks Jason, Thats not what I believe I was told and also from expereience, which sparked my original query.
I used a Resection from 3 surveyed (sideshot in FG) points. I changed one of the observations to one of the 'Control Points' and re-ran the raw file. The resection didn't change nor all the sideshot points from the resected point.
It got me wondering about Off-centre shots, 2 Line Intersections etc. If they are (like the Resection control Points) SP records then they would remain as such.
When you complete a resection the control points you used will be written as SP records and after the RS records you will see one final SP for the computed resection point. An example of a resection is shown below:
SP,PN103,N 3135.070,E 1511.185,EL399.795,--:

Many routines in FieldGenius will write a SP record to the raw file. SP records contain coordinate information that can be used for setups, resections, etc…

If this is so then we could end up with some points re-cordinated correctly, but some staying in original position before re-coordination.
Maybe I've misunderstood the process?
Richard Sands
Posts: 424
Joined: Mon Feb 14, 2005 1:10 pm
Location: Tasmania

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