Trimble Business Center

I made a mistake.
I had to define points at the foot of a mountain. I thought I would first measure below and then above, but I only had control points above.
First, I measured points (a1, a2, a4) at the bottom of a mountain, so that I gave a fictitious coordinate (100,100) and a fictitious Azimuth (90-00-00) to my Station point.
Then I measured from the top of the mountain with real coordinates three of the previously measured points(a1, a2, a4) . How can I adjust this fictitious coordinate and azimuth measurement together with the real, above measured coordinate? What I need to correct and how?

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Attila Tóth
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this is a bit of a tricky one and tbc is not that great at doing this. i can outline my approach, but others might do it a little differently. 

is it all one data collector file?? are the point names(numbers the same for both sets of observations?? these two questions might change the details of how to approach it. 

essentially tbc needs a close "starting" coordinate for the total station setup at the random location. i have done it by just clicking approximately where i thought it was on the screen. or you could draw 3d vectors of the total station setup and move then rotate to the correct location to create a decent starting point. it does not need to be perfect. once you have a close coordinate for the total station and backsight write it down somewhere. 

now you need to erase all data collector created coordinates. i select the area of the random data then advanced select/apply to current selection/dropdown for coordinates/apply then go to imported file in the manager and without clicking somewhere else expand the imported file and right click on still highlighted coordinates and erase. (we typically do this for the entire project and then create a control point usually at the base station location)

also delete or disable the azimuth record. you can click on it in the plan view and disable or erase. or find it with the view filter manager by turning everything else off. 

now go into the properties of the total station and backsight points, there is a button on the top right of the properties bar to create a coordinate for these points. enter the previously figured out points. and give them an unknown quality. 

depending on how the data was collected you might now have to merge the point pairs that are the same point in the real world. if they had the same point number in the field and were averaged this might add complexity to the problem and might need to be exploded and assigned different point numbers to be able to do the previous steps. if they had different point names now is the time to make the point names the same and merge them. 

after the merge run a network adjustment with your known control points and other data set(i assume you know how to do this part). depending on how you created the coordinates for the total station and backsight you might get some errors, but running the adjustment should force the total station/backsight coordinates to be better because they are unknown and the observed angles and distances are known. now you can use this iterative process to make the total station/backsight coordinates better, but after the first run they should be good. 

best of luck

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ian bissonnette
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Original Message:
Sent: 08-30-2022 04:13
From: Attila Tóth
Subject: Change fictitious measurment

I made a mistake.
I had to define points at the foot of a mountain. I thought I would first measure below and then above, but I only had control points above.
First, I measured points (a1, a2, a4) at the bottom of a mountain, so that I gave a fictitious coordinate (100,100) and a fictitious Azimuth (90-00-00) to my Station point.
Then I measured from the top of the mountain with real coordinates three of the previously measured points(a1, a2, a4) . How can I adjust this fictitious coordinate and azimuth measurement together with the real, above measured coordinate? What I need to correct and how?

------------------------------
Attila Tóth
------------------------------

Is it as simple as using "Transform Survey Points"? Helmert transformation and 7 parameter given there will be some degree of rotation. It asks for a "from point" (being your original A1 for what ever co-ordinate you have given it) and a "to point" (being the observed co-ordainte when you observed the points from the top). You have 3 sets of co-ordinates so will be perfect for the transformation. It will even show residuals on how well the rtransfoation fits your co-ordinate pairs. Once you match up first co-ordinate pairs, press the blue plus button to input the next pair.


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Shaune Dorron
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Original Message:
Sent: 08-30-2022 04:13
From: Attila Tóth
Subject: Change fictitious measurment

I made a mistake.
I had to define points at the foot of a mountain. I thought I would first measure below and then above, but I only had control points above.
First, I measured points (a1, a2, a4) at the bottom of a mountain, so that I gave a fictitious coordinate (100,100) and a fictitious Azimuth (90-00-00) to my Station point.
Then I measured from the top of the mountain with real coordinates three of the previously measured points(a1, a2, a4) . How can I adjust this fictitious coordinate and azimuth measurement together with the real, above measured coordinate? What I need to correct and how?

------------------------------
Attila Tóth
------------------------------

shaune. i never thought of that technique. might work well. but i am not sure what tbc would then do for the network adjustment. 
i guess our processing almost always deletes all data collector "coordinates" so that there is no chance that they have any weight in the network adjustment. but we might be overly cautious here. i would assume using the transformation that these coordinates would still exist(but should be good considering the residuals of the transformation).

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ian bissonnette
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Original Message:
Sent: 09-01-2022 21:12
From: Shaune Dorron
Subject: Change fictitious measurment

Is it as simple as using "Transform Survey Points"? Helmert transformation and 7 parameter given there will be some degree of rotation. It asks for a "from point" (being your original A1 for what ever co-ordinate you have given it) and a "to point" (being the observed co-ordainte when you observed the points from the top). You have 3 sets of co-ordinates so will be perfect for the transformation. It will even show residuals on how well the rtransfoation fits your co-ordinate pairs. Once you match up first co-ordinate pairs, press the blue plus button to input the next pair.


------------------------------
Shaune Dorron

Original Message:
Sent: 08-30-2022 04:13
From: Attila Tóth
Subject: Change fictitious measurment

I made a mistake.
I had to define points at the foot of a mountain. I thought I would first measure below and then above, but I only had control points above.
First, I measured points (a1, a2, a4) at the bottom of a mountain, so that I gave a fictitious coordinate (100,100) and a fictitious Azimuth (90-00-00) to my Station point.
Then I measured from the top of the mountain with real coordinates three of the previously measured points(a1, a2, a4) . How can I adjust this fictitious coordinate and azimuth measurement together with the real, above measured coordinate? What I need to correct and how?

------------------------------
Attila Tóth
------------------------------