Hi,
I'm wondering what software options exist to calculate positions of points, as observed from two known control points.
Context : I'm measuring features inside a building, and I'm using an older TS (Wild TC1000) that doesn't do reflectorless distance. So basically using it as a theodolite. For some features (mapping floor height), I've used a prism, but working alone is tedious and only gets worse for other features ( walls, windows, stuff on the ceiling etc).
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It makes perfect sense (to me) to just setup the TS on control point A, measure azimuth+elevation to all the features; then setup TS on point B, and measure Az+Elev on the same features. Solving for the intersections is then a simple trig problem. But either I'm not looking for the right thing, or no software I've seen has something already available for this ?
I'm using a TSCe to save data, but I don't think it can do these calculations. I checked in "Trimble Total control" (old stuff !), and couldn't see anything obvious. QGIS may have some plugins for this, but nothing stood out at first glance.
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Sure I can hack together a spreadsheet to do the math, but... hasn't this wheel already been invented many times over ?
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Thanks!
I use my least squares program to solve similar problems.?ÿ It operates okay with zero redundancy (no output statistics), but I'm not sure all LS programs will.?ÿ so you may want to do a few extra check measurements.
I used star*net (the original version, in DOS) exactly like that for many years... geometry matters.
it's kinda tough to get the accuracy needed for many projects.
There are simple survey programs that archaeologists use for mapping sites that might do that. I can't offer a name of one but do remember seeing something along those lines that worked with theodolites or abney levels.
It would be more efficient to rent a modern robot (or scanner) and get it done with certainty. Maybe not as much fun but cheaper and better...
The last time I needed that done quickly, I plotted the vectors in cad and pick my points graphically within the error triangles. I thought it was not very accurate until I measured the residual triangle sides and found them to almost nothing. Don't poo poo me, I poo pooed myself but got good data in the end.?ÿ
It would be more efficient to rent a modern robot (or scanner) and get it done with certainty. Maybe not as much fun but cheaper and better...
For a one-off project with a large number of points to nail down, I agree.?ÿ On the other hand, if you have occasional need for a few triangulated points, the cost of renting a robot or scanner for a day will go a long way toward buying a copy of Star*Net that you can use for all of your survey data adjustments.
I don't often need to triangulate anything -- maybe once every few years -- but Star*Net handles the calculations well.
Robots are fun! At least when working properly. I find some people who aren't familiar with them are amazed that it follows me around. The tech is interesting, at least to me.?ÿ
@jim-frame Completely agree. StarNet should be in nearly every toolbox..
SALSA software will do that for your easily and it's free.
@stlsurveyor Man, I'm having some starter trouble with SALSA.?ÿ I haven't tried importing?ÿ job files yet, but have tried just manually creating a simple 3 point traverse, local or arbitrary coordinate system based on 'known' geometry (fixed), then trying to get it to do an LS adjustment of 3 other 'floating' points nearby.?ÿ I've been reading portions of the manual, but am seriously missing something.
I would reccomend either getting a reflectorless total station by rental or purchase so you can measure distance and at least it will be easier for you when you process your data.?ÿ
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If budget is non-issue, get a scanner. Time saved in the field will be used in office slowly picking out the points required. But prior training is required.?ÿ
Whoa, thanks for the replies !
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star*net
Ok, that's a few times I hear that mentioned, I'll check it out for sure.
It would be more efficient to rent a modern robot (or scanner)
Agreed. But that would probably cost more than what I paid for my TC1000. I'm not pro at this (obviously), just playing the weekend league. There's essentially 0 budget for this project, I do it in my own spare time.
I'd love a reflectorless TS but they're still a digit more than I'd like to spend. Maybe they'll drop in price more in a few years... unless someone has a unit needing repairs lying around, and is willing to part with it at an insultingly low price ? : )
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SALSA software
StLSurveyor, thanks. Certainly looks like it has some learning curve, but should be manageable. It does seem to like ECEF coords though, hopefully I can
Right, so I was missing the keyword "least squares adjustment", and what I should really be doing is also measuring a third set of angles from another control point.
I had assumed this was a "for profit" endeavor, and a bit larger volume, so my response is changing.
In your original post you suggested using a spreadsheet. Great idea.
Combining a single solution with redundancy (third set of angles) would be just fine.
Your spreadsheet could be simple (visually compare the three solutions) or more elaborate with the differences?ÿ
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maybe I will hack something together, I too use triangulation...but I usually use pencil and paper.
