Hi all,
Made a bit of a boo boo the other day and hoping someone knows an easy fix for future reference.
I resected into control and measured a series of points with a scale factor of 0.9996 applied when in fact I should have had a scale factor?ÿ 1.0002 applied. Yes, the resection wasn't great because of this either, but it didn't matter for the purposes I needed it for.
I'm using a Trimble TSC3 with Trimble Access. How would I transform those observations into the correct scale factor? I am thinking I have to take into account the station set-up as well? I tried using the transformation tool under COGO but I'm concerned it won't take into account my station set-up.
Cheers
?ÿ
I did the same thing a couple of weeks. Only way I found to correct it was in my CAD program. My TSC3 did alot of weird things that day.
When you are able to know the control length and the newly resection length it is quite obvious if over or under "1".
I would rather collect data in 1:1 actual acquired data and perform any corrections and adjustments later in the office after I had analyzed the information.
When you are able to know the control length and the newly resection length it is quite obvious if over or under "1".
I would rather collect data in 1:1 actual acquired data and perform any corrections and adjustments later in the office after I had analyzed the information.
Like
Depends greatly on the actual calculations for the resection. If it was distance-distance resection then a rescaling will not work. You must first rescale your resection observations, recalculate your resection point and then scale and rotate your field shots.
If it was a two point free station using the SMI method then a simple rescaling with the correct base point will correct everything.
If it was some other method, I would need a lot of details and raw data to help you get it right.
Paul in PA
When you make this goof in the field and stake things based on it, the fix generally involves a return site visit.?ÿ But if it's just a "paper" mistake (nothing set yet), then Star*Net is your friend.
SOP for me is to convert DC raw data to Star*Net input and adjust therein.?ÿ This applies to resections as well as other measurements.?ÿ DC scale factor doesn't come into play.
I would never feel comfortable with an office ??fix? without returning to the site for a check. So I would likely redo the resect. But it might be worth trying the office fix and checking in the field to determine if the office fix would be a reliable solution for you in the future, eliminating an additional trip to the site should this happen again.?ÿ
It is crucial in a correction to know exactly what your DC software did.
Paul in PA
@manxmaid "easy fix for future reference" make sure you record All measurements. Black Boxes sometimes spit out Wrong answers, you need to check it.
If done correctly the controller should always record the raw measure without scaling the distances. Therefore you should be able to reprocess the raw data using what every scale factor you want. Do NOT apply scale factor to coordinates.
So I would likely redo the resect
What part of your raw data don't you trust??ÿ I can't see going out to take the same measurements again just because the calculated coordinates are wrong.?ÿ As Paul said, it's critical to know what was done, but that's what raw data is for.
If the resection yeilded a bad scale factor, then your field measurement did not agree with your computed distance between the points. So you need to start solving that problem, then move forward from there.
I'm a little late to the party here but if your coordinate system in Access is "Scale Factor Only" then all you have to do is go into the properties of the job and change it to the correct value - as others have said, Access stores the raw data; it will recalculate all of the coordinates, including the resection.