@john-putnam Sort of points to a disconnect between the RLS and the field crew left to figure things out on their own. In my experience a very common problem where the LS and office people live in one world and the field crews live in another and there's little by way of direct overlap and guidance. In the past I've had some major problems with field guys getting projections mixed up, knowing their data has issues and then handing it off as 'not my problem' since nobody is taking the time to work with them to show them what and what not to do. I've seen it get downright toxic when egos get involved.
Just because I'm paranoid, doesn't mean they aren't out to get me.
Yes, that's right when only a total station is used.
When Captivate's Determine Coordinate System app is used to match lat-lon to rectangular coordinates, it's different. I don't know the particulars, but from what little I can gather, Captivate can create a TM projection. Whether it always does, has to be asked to do so, or can also create a Lambert projection is beyond what I can find quickly.
Whenever lat-lon is converted to Northing-Easting, a projection has to be defined. Lat-lon is specific to a particular ellipsoid. A mapping algorithm that duplicates the math needed to convert points on an ellipsoid to analogous points on a map does the work.
Thank you for pointing that out. Not ever job requires an ellipsoid-derived plane coordinate system and Leica, for one, supports an alternative.
That is a different situation. The Determinant Coordinate System app does assume a projection, depending on the transformation technique you specify. The app can be used similarly to field calibration in Trimble speak or a true 7 parameter geodetic transformation between know geodetic control. Any time you utilize the app you end up with a coordinate system attached to your project. You can still have a project with no underlying geodetic datum and use it for total station work. I'm pretty sure you can even collect GNSS data with no coordinate system, it just does not show up until you add one. I know you can add a geodetic coordinate to a project without a coordinate system, you just don't get an associated local grid coordinate. My point was that, while rare today, not every project is on a geodetic coordinate system. Some are still on based good old 10000,5000 and a compass bearing north. That is the only time I would set my TS 0ppm.
That is the only time I would set my TS 0ppm.
Surely your total station would never be at 0ppm unless the temperature and pressure happened to be exactly the equivalent of 0ppm. Otherwise any deviation from the standard temperature and standard pressure will result in a ppm compensation in the measuring of distances.
Indeed. I've marked axes on a tile floor to teach coordinate calculations. Students calculate oblique distances from coordinates and checked their work with tape measures. That put an abstract concept into the real world and gave context to what is totally boring for many students.
You made a great point!
I'm not sure what there is not to trust about it.
It's probably more to do with not training and consequently not trusting the field crew to execute the scaling right.
Computing the combined factor is a simple math formula once you know the projection and location.
Right, though it does make me wonder why if it's simple math like that then why do the different softwares come up with slightly different scale factors when the exact same projection and location data is used in the calculation.
At each control point pair, if you are just randomly selecting one control point as good and adjusting the back sight distance based on the total station measurement before setting your new corners, it seems like you would be slinging error around like a short order cook slinging out fries.
I agree. Also, if you decide to reverse your setup it gets even messier.
There also seems to be some confusion as to whether the scale factor is 1.00000000 or something else.
I looked in the raw data file and the scale factor was 1.00000000. I have to investigate that further.