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Orientate instrument using two unknown but accessible traverse points.  

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squowse
(@squowse)
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December 3, 2018 9:47 am  

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.

 

 


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half bubble
(@half-bubble)
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December 3, 2018 10:07 am  

Have to bootstrap it somehow if one does not know which buttons to push.

It's difficult to entice new people into the profession without discussing proctology.


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Enri_F
(@enri-f)
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December 6, 2018 8:10 am  

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 


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Enri_F
(@enri-f)
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December 9, 2018 8:45 am  

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

 

😀


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squowse
(@squowse)
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December 9, 2018 6:22 pm  

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.

This post was modified 2 months ago by squowse

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Nate The Surveyor
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December 9, 2018 7:04 pm  

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 N12ø13'14" E 822.56'.

Now, we go find the prev coord for these ctrl pnts. And, that the brg is N13ø15'20" 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

 

Surveying is more than a Job----it is a passion to provide a foundation for future generation, that is beyond reproach.

Nate


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Javad GNSS

squowse
(@squowse)
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December 9, 2018 11:22 pm  

wow that's complicated!

but he doesn't have the co-ords for the points or even a bearing between them so no rotating or anything else till he gets them.

i think he's an engineer starting out. had some teaching at uni but not really got a feel for it yet. needs some help from someone on the ground.

 

 

 

 

 


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christ lambrecht
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December 10, 2018 3:46 am  

He has the TOPO in CAD!

my way would be to open the cad file, have a look at both control points, make sure there is a simple 3D-point on each one, a line between both would be fine but not really necessary. Make sure the point name is as text readable and save as dxf to use it as map in Trimble Access on the tsc3.

on site use the resection station set-up, give your station the desired name (no assumed E,N,El), tape you HI., go to map view, select your first control point, switch to resection, in the name field for pointclouds shoot select the option ‘Select from Map’

since you already selected that one point it will be added for you’

repeat for second point

select calculate and you’ll be presented with the error values of your resectionand if ok with the E,N,El and your Azimuth, and you can start shooting other pointsin the same reference frame of your control points.

if you have all data digitally available use it digital and keep away from keying in manually! Humans make to many misstakes, computers don’t.

christof


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Nate The Surveyor
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December 10, 2018 5:18 am  

A part of my answer is wrong. You will need to use 3d for it all, and keep track of elevations. It's just getting deeper. Not hard, but I honestly suggest you get a bit of help... In person.

Surveying is more than a Job----it is a passion to provide a foundation for future generation, that is beyond reproach.

Nate


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Enri_F
(@enri-f)
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January 11, 2019 6:46 am  

Not that I am bothered by the wrong part, but if you have to spell this out for me, you just might be in water too deep for yourself.... 

Take care,

Enri


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Enri_F
(@enri-f)
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January 11, 2019 6:50 am  

Sorry everyone to steal your spare time and if I am not worthy for this forum, but when i subscribe i never thought that between surveyors I could ever meet this kind of gentleman's.

Anyway, Christ I do agree on this way to do it, but I just did it as I said, because I didn t want to put any coordinate, just in processing , letting myself free of any constraint. Once in the office arbitrary and osgb has been computed in the way that the free station elevation has been computed, whit the coordinates.("the program did the resection !").

Nate , what is a magnetic compass ? there is no need to compute distance BC, it has been assumed correct since it belongs to a computed traverse.

Nate, what is this question:

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?

It is just not inherent to the topic. You did ask even something else, but i preferred not to read all the row until the end.

This post was modified 1 month ago 2 times by Enri_F

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Nate The Surveyor
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January 11, 2019 7:28 am  

It is just not inherent to the topic.

Well, maybe it is. I should know how far astray you are going, before I help you get there!

If you are adding to a real job, you may be in "big heap trouble".

If it's a student, doing exercise, you will eventually see the trouble you can be in.

If it's a "nuklar" plant, you are get us all blowed to bits!

N

Surveying is more than a Job----it is a passion to provide a foundation for future generation, that is beyond reproach.

Nate


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leegreen
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January 11, 2019 7:54 am  

Reference Line can be a good routine when you understand how to use it. This routine exists in Topcon Magnet Field and sounds like it may be the same in Trimble. Most people on this board have not used it and are not familiar with its purpose. But I believe it may be the tool you are looking for. It is handy when you are in construction and need to align the project between only two known control points, say a building or column line. Ref Line is basically a 2 point resection, but better, in that it helps to identify the error and allows the end user to apply the error accordingly. Basically, you first tell the controller the name of the unknown which the instrument is occupying. Then measure to known "A", then measure to known point "B".  The software will prompt you with the measured vs. computed error between A and B. Say the error is 0.04'. You have three options.

  1. Hold point A, rotate into point B, the distance error is on point B.
  2. Hold point B, rotate into point B, the distance error is on point A.
  3. Average the error Between point A and B, rotate between into points A and B, the distance error is spread between both points.

~LeeGreen.com
Licensed Surveyor in NY
sUAS Remote Pilot


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Norman Oklahoma
(@norman-oklahoma)
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January 11, 2019 8:21 am  
  1. Nate was trying to gauge your level of experience so that he could tailor is answers to suit his audience.
  2. A magnetic compass is simply that very most basic of all surveying tools. The thingy with the floating needle that points at magnetic north. 

"Convention is like the shell to the chick, a protection till he is strong enough to break it through." Learned Hand


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Brad Ott
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January 11, 2019 9:10 am  

Nate, for the record friend, is one of the very best humans to participate on this forum.

Beer Leg dot com R O C K S ! !
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