Forgive the rambling and pretty non-specific nature of this question, but I've been taking a break from the sometimes headache rendering threads on Star*net, and spending some time studying the mundane functional capabilities of the total station...specifically "Coordinate Data".
So, the question is this:
If one does not need to tie a local survey to the geodetic grid, which is coordinate based, How is "coordinate data" practically used in a local survey? When you measure, it's radially based, i.e. angle and distance from a (presumably known) location. If you plot in CAD a lot, a building, or whatever, then go into the field to stake it out, you're going to do it from known locations, then site an angle and distance.
I understand that the "under the hood" communication to CAD IS coordinate in nature, but, unless you're going to use a tape (or chain) to measure out points in X and Y, of what practical use is the "coordinate data" capture or regurgitation in the total station?
Polar coordinates.
Same Cartesian plane... different road-map... or, maybe, power steering.
I remember being a grunt, following along with my bush-hammer, cutting down mature pines to satisfy the I-man's whim.
I always liked math and couldn't ever figure out why we needed (Theta, x).
Fast forward to the epiphany of running the 'gun'.
Sweet. I can go from here to there without making 90's at every turn.
Add-in a 'dc', some CAD and a couple of good guys and you're as free as you want to be (I've never done gps to speak of. however, it's still the same. someone's just doing the lion's share of the 'z' for you in your magic box).
To your questions: how do you stake that building, storm system, road with your fancy gadgets, from your 'known' points?
How do you "known" your points.
coordinates. nothing else.
Angle and distance from a setup/ backsight give you a 'polar' description to your next point... still a part of your coordinate system. trigonometry.
Which just gave life to the thought: is trig a sub-set of geometry? A slice of shape-study focused solely on the triangle. It sure is important; they gave it its own class.
Alright. gone off the deep-end. Have a good one and good luck.
Coordinate useage has been around a long time before total stations, EDM's and GPS.
> Coordinate useage has been around a long time before total stations, EDM's and GPS.
I was talking about cartesian coordinates (although it looks like you can rotate them as you wish in the instrument.
I guess the answer is: It's legacy...before modern total stations came about, and of little practical use to the surveyor?
Cartesian coordinates are generally the most useful representation of your data when you want to calculate relationships of points. Given some angles and distances, possibly redundant, it is not always easy to solve for another angle or distance, and there is no general formula. Polar coordinates from some chosen point usually require more calculation to derive something not measured.
Turning the measured angles and distances into a best estimate of cartesian coordinates for each point gives you a representation from which it is easy to derive angles and distances for any subset of your points, using a relatively simple set of formulas.
I think most software, whether in the instrument, data collector, or CAD package, is based on this principle, as were the manual calculations shown in textbooks.
:good: Well said, Bill.
I guess the answer is: It's legacy...before modern total stations came about, and of little practical use to the surveyor?
Ahhh, not really, of great PRACTICAL use to the surveyor, a way of making each point quickly locatable to any other point in your survey, been around a looooooonnnnnggggg time, usually as northing, easting, but I've seen northing, westing, and southing, westing, they are all good, just need to know what is being used. 😉
And as a surveyor I usually express the coordinates as northing, easting which is Y X, not X Y, but often easting, northing is used by others.
I call BS on all this coordinate stuff... it's latitudes and departures for me... no need for all that fancy new fangled coordination.
Excellent explanation. Makes sense. Thanks.
Here, here! 😀
Wish I could do that 'thumbs up' thing that I see others do. htmhell.
While this has been well beaten so far, it won't hurt to say it a different way.
'Coordinates' is a term covering a myriad of expressions of spatial relationships. Each system of expression has its own purpose. At the risk of being branded a heretic, the PLSS is nothing more than another expression of coordinates. The main distinction being the addition of several volumes of rules a good deal of history and law.
Absolute coordinates apart from the data used to generate them have little value. In many survey problems they are invaluable...
Coordinate Data Question...Follow up question
This is partially related to my other thread about importing data to Topcon Tools from the TS.
In the TS, you can capture "measurement data", or "coordinate data". My understanding is that the TS calculates (internally) one from the other.
Does anyone know whether, using a data collector, if the DC is just captures coordinate data, imports it to CAD (Carlson, Microcad, ACAD, etc.) and allows the office program to do the same thing (calculate the measured data)?
Topcon Tools has the ability to calculate coordinates from measured (direction and distance) data; not sure about the other way around.
I guess the question is this: Using a DC, what, exactly is it capturing and sending to CAD?
Coordinate Data Question...Follow up question
Our current work flow these days usually involves Magnet Field and Topcon Tools.
The field software stores both data and coordinates. The crew uses the coordinate data for their end of things (search calcs, line checks, etc.).
Once in the office I import to Topcon Tools. I decide what gets held and run the adjustment. This is more to quantify the data than actually 'improve' it. Once the coordinate error ellipses are good I export coordinates.
We convert our coordinates to a softdesk fieldbook. This is them brought in and the linework is generated automatically.
It is possible to import the raw data and adjust in Civil 3d. I got tired of the constant 'upgrade' game and went third party. To be truthful I will probably go back to StarNet 100% once they allow import of native RTK field data.
Hope this helps, Tom
Coordinate Data Question...Follow up question
> Hope this helps, Tom
That helps a lot, actually. Thanks.
> The field software stores both data and coordinates.
I have my instrument set up to create a coordinate data file automatically. See here:
I've tried bringing both files into Topcon Tools, and get a pair of screens comparing coordinate data in the file with coordinate data in the job and asking what to do about it...I have some studying to do to figure out what that's all about.
But in the mean time, you wouldn't have a Topcon Tools file of perhaps a traverse that I could study and compare with what I have coming into the program from the instrument, would you? I'm limited to 5 points at the moment, but I think if I try to load a file with more, it just uses the first five. If that's a pain to come up with, I understand.
> We convert our coordinates to a softdesk field book.
>To be truthful I will probably go back to StarNet 100% once they allow import of native RTK field data.
Finally, do you know if there is any of the multitudes of file formats for export from Topcon Tools, that can be input into StarNet directly? That's where I'm ultimately going with my data.
