I am wanting to see if anyone has a method, or knows of a simple piece of software to process traverses using raw coordinates only.
If I have a coordinate file only with just unadjusted points, knowing the direction of the traverse through the points, the sideshot points and also a scale factor where necessary....is there a program that simplifies handling this without having to manually calculate the raw angles/distances??
All adjustment routines use the same basic principles. You must have one of two things. Either two coordinates that are supposed to be exactly the same but are not or multiple measurements that can be used to calculate what is supposed to be one position. If all you have are coordinates, then you lack the basic data required to adjust anything.
Unless of course what you have is a beginning coordinate and and ending coordinate that are supposed to be the same but are not. But if you use that as the sole basis of an adjustment you are making lots and lots of assumptions that are almost certainly invalid. If you are going to do that, why bother adjusting at all?
Your data collector should allow you to export raw data. Use that rather than coordinates.
Larry P
I agree with Larry.
You can't adjust anything unless you have redundant data, check measurements. Closing a traverse can provide check data, as can other "extra" measurements.
What are your redundant/check measurements?
You are always better off doing the adjustment with the basic measurements (angles, distances, GNSS vectors) and not something (coordinates) derived from those measurements.
I am actually running between known coordinate pairs, from DOT provided data, usually around a land section or two and then returning to the control. Occasionally the crew may do something that varies from the data collector software's normal traverse routines and I have to deal with things manually. I am just wondering if there was a simple way for me just to dump the raw coordinates into a program, define the traverse route (point list?), give it the starting and ending known point data and provide a closing angle.
> I am actually running between known coordinate pairs, from DOT provided data, usually around a land section or two and then returning to the control. Occasionally the crew may do something that varies from the data collector software's normal traverse routines and I have to deal with things manually. I am just wondering if there was a simple way for me just to dump the raw coordinates into a program, define the traverse route (point list?), give it the starting and ending known point data and provide a closing angle.
There is software that will adjust traverses from coordinates if one is willing to settle for Bowditch's Rule (aka Compass Rule) as the method of adjustment. I still have an old version of COGO that would do just that as long as the sequence of point nos. on the traverse route and closing angle is known. The sideshots would be another matter, though.
> You can't adjust anything unless you have redundant data, check measurements. Closing a traverse can provide check data, as can other "extra" measurements.
>
> What are your redundant/check measurements?
As I understood the post, there is a closed traverse, but it is represented in terms of provisional coordinates calculated from the unadjusted observations and a measured angle where the traverse closes. That would be two redundant observations and sufficient for an adjustment.
The first thing I would check is to compare the end to end inverse of your traverse with the inverse between the known stations. This will tell you if you are in the ball park or out in left field. And depending on what you are doing, it may be "close enough for government work".
Then I would figure out just what the known coordinates are. Are they state plane coordinates? Or just some ground coordinates. If state plane, then apply the combined scale factor to the distances of your traverse. I know you said you have coordinates, but you may need to use those to calculate what the angles and distances are. After adjusting your ground distances to grid distances, recalculate your traverse and then check the end to end inverse again.
If the end to end is good in either of the above 2 processes, then you have a couple of choices as to where to go. If your end to end is real good, then a simple rotation of your traverse may be good enough.
If you have a good backsight angle and a good closing angle, you could try any of 3 possible adjustments - transit, compass, crandall. Maybe try all 3 and compare results.
There are lots of possibilities of what to do and your intuition will play a large part in your decision making.
None of this is a simple one step process. You need to do enough analysis to figure out what you have and what your comfort level is.
A Traverse Adjustment Requires The Traverse Elements
That includes the raw traverse angles observed, the traverse distances, forward and reverse and all redundant side shots and any check shots. A requirement of a traverse is that all traverse points have a 3 traverse point observation. In other words it must be a closed traverse.
Adjusting using traverse coordinates only is called scaling and is not that useful.
Paul in PA
A Traverse Adjustment Requires The Traverse Elements
> That includes the raw traverse angles observed, the traverse distances, forward and reverse and all redundant side shots and any check shots. A requirement of a traverse is that all traverse points have a 3 traverse point observation. In other words it must be a closed traverse.
Actually, it certainly is NOT true that all lengths of traverse legs need to be measured backward and forward. It's good practice but hardly necessary to generate a closed traverse with more observations than are minimally necessary to describe the figure, i.e. a traverse that needs to be adjusted.
In the case of provisional, unadjusted coordinates that were computed by a data collector from angle and distance observations, the input angle and distance measurements should be easily calculated from the provisional coordinates. Some traverse adjustment software does just that.
A Traverse Adjustment Requires The Traverse Elements
> In the case of provisional, unadjusted coordinates that were computed by a data collector from angle and distance observations, the input angle and distance measurements should be easily calculated from the provisional coordinates. Some traverse adjustment software does just that.
My old HP48 with SMI did that. You calc'd provisional coordinates and they were adjusted. For a 4 cornered traverse, you might start on point 1 and your closing point would be point 5. After adjustment point 1 and point 5 would be equal. Compass rule.
The original DOS program Carlson Surveyor 1 will work with and adjust from coordinate files only
It will also use the complete angle, slope distance, vertical angle information and do a complete angle adjustment and balance the traverse horizontal and vertical
Will do Traverse, Compass and/or Crandall methods
There is also a routine to find the most likely setup for blunders and errors
0.02
Actually the last version of Carlson we purchased (3 years ago) 'processes' GPS data computed from stored coordinates. If your ref file or rod height had an issue you are toast..
As for adjusting coordinates, it was the standard for quite some time. That method faded from common use between 15 and 40 years ago depending on geography. It's too easy to use more robust methods these days to justify not doing it. Least Squares all the way for me...
Sorry Kent
If you do not measure the forward and back, you will never no if they are right. I will give you after the backward measurement you may accept the forward as correct, otherwise you are not making true measurements. Only measurements can be adjusted.
Paul in PA
A Traverse Adjustment Requires The Traverse Elements
> My old HP48 with SMI did that. You calc'd provisional coordinates and they were adjusted. For a 4 cornered traverse, you might start on point 1 and your closing point would be point 5. After adjustment point 1 and point 5 would be equal. Compass rule.
Sure, at one time the efficient use of memory was a big deal and the approach of working the adjustment from the provisional coordinates was a good way to solve the problem.
Sorry Kent
> If you do not measure the forward and back, you will never no if they are right. I will give you after the backward measurement you may accept the forward as correct, otherwise you are not making true measurements. Only measurements can be adjusted.
Actually, distance measurements are measurements. The mean of two measurements between the same points should have a lower uncertainty than either of the individual measurements, but certainly won't determine the absolutely correct distance between the points.
The reality is that all measurements of quantities such as distances and angles are estimates of quantities that cannot be ever exactly known. A very good measurement may have a very small uncertainty, but there is still an uncertainty present in whatever value is adopted. Pretending that one can somehow determine the "true" measure of such a quantity is not consistent with reality.
PacSoft will do it. The sideshots, on the other hand, are a completely different matter. Hope the loop was tight!
A Traverse Adjustment Requires The Traverse Elements
> That includes the raw traverse angles observed, the traverse distances, forward and reverse and all redundant side shots and any check shots. A requirement of a traverse is that all traverse points have a 3 traverse point observation. In other words it must be a closed traverse.
>
> Adjusting using traverse coordinates only is called scaling and is not that useful.
>
> Paul in PA
Paul, not it's not. The software that adjusts loops based on coordinates alone breaks them back into their component parts of angle and distance, adjusts the angles, then applies the compass method. It's not scaling, it's true adjusting. You're confusing field methods with the engine driving the adjustment, which, are not the same.
The same package that will adjust the coordinates from a loop, could have had those "provisional" coordinates generated from field methods EXACTLY like what you're saying, so, I repeat, you're mixing apples and grapefruit.
A Traverse Adjustment Requires The Traverse Elements
I use my SMI v7 on HP48 to balance angles and adjust closures
I keep the original raw data file, original coord file and adjusted coord file for records.
:good:
The program used depends upon whether one is working in a geodetic environment or doing Plane Surveying down here in the flatwoods territory where everything is mostly between 200 to 400 msl.
The Carlson Crandal rule is as close to a true DMD adjustment as I have found outside of doing every step by hand on DMD sheets.
A Traverse Adjustment Requires The Traverse Elements
"Paul, not it's not. The software that adjusts loops based on coordinates alone breaks them back into their component parts of angle and distance, adjusts the angles, then applies the compass method. It's not scaling, it's true adjusting. You're confusing field methods with the engine driving the adjustment, which, are not the same."
If you're simply closing on the starting point then you aren't necessarily adjusting your angles as the compass rule adjustment will, by necessity, adjust them for you.
small point.
