Activity Feed › Discussion Forums › Strictly Surveying › Orientate instrument using two unknown but accessible traverse points.
Orientate instrument using two unknown but accessible traverse points.
Posted by enri-f on December 2, 2018 at 7:32 pmHi guys, I was wondering if is that possible to orientate my t6 (and my pick ups utils lines) by knowing /shouting two Control Stations location without knowing their coordinates. Could it be done by RefLine? if so, how ?
Thanks in advance !
nate-the-surveyor replied 5 years, 3 months ago 13 Members · 36 Replies- 36 Replies
Not sure I understand your question. You seem to have an unknown instrument position and unknown control points. Just what is known in this scenario?
If I understand correctly, you want to do a resection later when you know the coordinates. I am not aware of any software that will do that, but, you can do it by hand after collecting as a topo
If Norm is correct, you could do that sort of calc in StarNet.
Well I do have two control stations that belongs to the traverse, and I was wondering if is that possible to get my instrument orientated in a scenario where I just put 100,100,10 coordinates at any point where I stand with the instrument , shoot the traverse stations from my instrument position (like using them as reference line) get the distances from those.
Do I get an orientation like this? Actually I am not sure this can be performed with Ref Line. Honestly, I never used this program on the s6 and I don t have a very good idea on how to get my instrument aware of his relative location.
I can try to put it like this.
Is it possible to survey having two control points available to be shoot(RO) of which you don t know the coordinates , using them as a kind of false resection stations ?
We have a site on which a topo has been done by some one else and we would like to use his stations to pick up utility’s marks. Can this be done without knowing the coordinates of the two RO ?
If so , is it using RefLine or some other Trimble’s programs that you can perform this task ?
Just as a field work , then probably later on some one will ask for this coordinates and impute them in the post processing .
The easy way to do this is to just set up and shoot the reference points and the utility info you’re looking for. Export the coordinates and then translate and rotate in CAD.
You might be thinking of the “orientate to line” method of setup. But that won’t be any use unless you know some coords.
As Stephen says, just set up on assumed coords and shoot the stations in the same way as your other topo points. The survey can then be transformed onto the correct co-ords once those stations are known.
Exactly what I meant to do guys .
I just don t know how can I perform it with my trimble s6. Is it by using ref line or is there any other program available on trimble ?
Do you know how to set up on assumed coords?
No Squowse actually I don’t know, it would be great to have a description on how to do that .
Are you using a data collector of some sort or does your S6 have a faceplate with data collection capability? Most S6’s don’t have the ability to much of anything without a data collector and unless we know what kind of equipment you’re using specific directions are not possible.
Is a s6 total station with tsc3 Stephen
Set up on one point. Measure a distance to the other point. Call the first point “5000, 5000”. Let us say the distance measured is 330 feet (use Communist Yards if you must). Call the second point “5330, 5000”. That line is your “job north” for gathering data. Now set up off to the side somewhere and shoot the distances to each point and turn the angle between and you can trig your way to the setup coordinate with paper and calculator, or use the resection program in the data collector.
That is a way ,thanks Half bubble !
Do you have the other guys topo in CAD or only in paper or pdf? If you have it in CAD you can draw a line between the control points and query the line for the end point coordinates. Plug those into your tsc3 then resect using the control points or occupy one and backsight the other if possible.
Kind of don’t need to do all that setting up and measuring between the points first.
Just set up anywhere you want to start your survey. Do a station setup with assumed coordinates eg 500,1000,10. For orientation, just orientate by angle ie point approximately north and set angle to zero. Then just start surveying and measure the stations and your other topo points from this or any other setup.
Have to bootstrap it somehow if one does not know which buttons to push.
OK , this thing is called free station .
It gives you the freedom to put the instrument wherever, calling the standing point 100,100,100 or 10 and orientate your instrument to one Control Point of the traverse , and foresight the next one.
This is how I understand it. But you actually are doing a resection. I just don’t get what kind of transformation is involved between my arbitrary point or points in case I do this for a long – big project , and the lets say OSGB36 . 🙁
Gosh I hope I have got it right so far. Please let me know what do you think
Hi Stephen, yes I do have the topo, but I kind of don’t want to make to many things that I can do in the office processing the data just go there and trig the control points and get away with that
😀
No you haven’t…
What don;t you understand from all the advice that has been given?
Freestation is the same as resection and is used once you know the coordinates of the points.
If you don’t have any coordinates when you are in the field then you just measure the station points using an invented local coordinate system. The adjustment can then be done later.
I described before how to set up on a invented local system.
Presumably this job should have been done by now? You might want to involve someone more experienced to show you the ropes.
Why have you not been given coordinates to work from? It seems like your skill level is not up to starting a survey and tying into the previous work. You might be better off demanding station coordinates before you go any further. If they are OSGB36 then Access will use the correct scale factor once you choose OSGB36 as the coordinate system. They need to be proper OSGB36 though, generally I find that scale factor 1.0 has been used even if the coordinates appear to be OSGB36.
Here’s how I’d do it.
Set up inst. on arbitrary 50k/50k and set a nail there. Then, using a magnetic compass, observe the direction to one of the control stations, with a distance, reduced to horizontal.
Then, using that ctrl point as a backsite, I’d zero the inst on it. Then, turn angle to the other ctrl station, and measure the (reduced to horizontal) distance.
We can call the inst point A, the backsite B, and the fireside C.
Now, we have a triangle. With a bit of trig, we can compute line B-C. Let’s say we find it to be N12??13’14” E 822.56′.
Now, we go find the prev coord for these ctrl pnts. And, that the brg is N13??15’20” E 822.60′.
We now rotate pnts A B and C so that line B-C matches the prev brg.
We now can make a mid point between B and C.
We also make a mid pnt between the original ctrl pnts.
We now translate points A B and C, and the mid point, so that the mid points of our control match the mid point of the control stations.
Now, my point is this. All the above is very normal for any surveyor. A standard exercise. Are you an engineer? Or, a student, or what?
Why do you come ask to borrow our every day tools, that we make a living with? Not that we are bothered by sharing, but if we have to spell this out for you, you just might be in water too deep for yourself….
Take care,
Nate
Log in to reply.