The same could be said of a traverse that has been adjusted by least squares or compass rule or whatever. You could not truthfully state that the resulting numbers after adjustment are exactly what you saw on your equipment in the field. Does that mean you're not being truthful? No. You are dealing with data analysis and adjustment that non-surveyors have a hard time understanding.
As I said in the CLSA thread, that happened to me in a deposition where the issue was the distance from a building corner to a property line. The other side had their survey, our side had mine. The question was asked whether my survey agreed with the other survey and I said something like "within an acceptable margin of error" so they proceeded to focus on the word "error" for an hour or so, as if it's a bad thing. What should I have said? "No, the building corner is 10.25' from the property line, not 10.23' as shown on the other survey?" To me, that would not be a truthful statement.
You classically measure a parcel: setting up on each monument and traversing the property in order; closing on your point of beginning. Then, you see that there is a misclosure (which there will be) and "adjust" your measurements. Are you returning "measured" numbers?
Or you measure the monuments with vectors; occupying each monument multiple times and then "adjusting" the results. You then inverse the bearings and distances and label your line work. Again: are these numbers "measured", or they calculated, or are they adjusted?
If you return your actual measured numbers the parcel might not close. Wouldn't that just be awful? Labeling a line with a 1 second bearing on a town lot is really kind of silly, but at least it closes which I guess is the main result everyone looks for.
> The same could be said of a traverse that has been adjusted by least squares or compass rule or whatever. You could not truthfully state that the resulting numbers after adjustment are exactly what you saw on your equipment in the field.
Well, any professional surveyor should testify that no measurement can be entirely free of uncertainty, and the values shown on his or her map are simply very good estimates based upon measurements that were made and that most non-surveyors would think were perfect for most practical purposes.
If you saw some of the maps that have been recorded in Sacramento County, maybe you would reconsider. Much of the County is made up of blocks that are 1/4 mile X 1/2 mile divided up into old 10-acre lots that were created 100 years ago or so. Those lots have been split up into 10-50 parcels each. There are maps with ten different opinions of the lengths and bearings on those lines stacked on top of each other with maybe eight of those being what I would consider statistically identical. What is the purpose of that? To show agreement? Sorry, I'm just not getting it. If every one of those parcels got surveyed, should we have hundreds of different opinions of the same line?
In Florida...
it's a no brainer....
5J-17.052
7.
b. A comparison between recorded directions and distances with field measured directions and distances when they vary.
:coffee:
it seems that there are two kinds of surveyors
those who fudge their measured distances to agree w/ record and those who don't.
In Florida...
The question I have is whether there is a threshold that needs to be crossed to state that a measurement "varies" from record data. I think there is.
it seems that there are two kinds of surveyors
"Fudge" is such a negative term.;-)
Is it "fudging" to adjust a traverse into a closed figure or adjust a level loop?
Mr. Reuben J Cogburn will take the stand.
You were sworn this morning, you're still sworn.
Defense will cross-examine.
Mr. Cogburn, you testified for the prosecution this morning. Allow me to summarize what you said. According to your story C C Wharton grabbed a shotgun and killed Marshal Potter. Then he turned the gun on you, and you shot him. Then the father swung his axe, and you shot him, too. The defendant tried to run, you say, and you also shot him.
Just winged him, or he wouldn't be here to pay up! The old man and CC hit the ground dead.
How long have you been a Deputy Marshal, Mr. Cogburn?
Four years, come March.
How many men have you shot in that time?
- The prosecution objects!
- Overruled!
How many men have you shot since becoming a marshal?
I never shot nobody I didn't have to!
That's not the question. How many?
Shot or killed?
Let's restrict it to killed, a more manageable figure!
Well, twelve to fifteen, stopping men in flight and defending myself.
Twelve to fifteen? So many you can't keep a specific count. I have examined the records. A more accurate figure is available. Come now, how many?
Counting them two Whartons, twenty-three.
I felt you'd come to it with a little effort.
Twenty-three dead men in four years. That makes about six men a year!
It's a dangerous business.
How much more for those you arrest.
Is it not true that you sprang upon the Whartons with a deadly six-shot revolver?
I always try to be ready.
Was this revolver loaded and cocked?
A gun that's unloaded ain't good for nothing!
Just answer, if you please.
The question don't make sense!
-Don't bandy words with counsel.
Yes, sir.
You testified you backed away from old man Wharton.
Yes, sir.
Which direction?
Backward! I always go backward when I'm backing away!
I appreciate the humor of that remark. Aaron Wharton was standing by a pot when you arrived?
More like squatting. He was stirring the fire under the pot.
How far did you back away?
Six, eight steps.
Meaning Wharton advanced the same distance? Six or eight steps? Sixteen feet?
Something like that.
Then explain why the body was found by the wash pot, one arm in the flames, the sleeve and hand smoldering.
Them hogs! They may have moved the body.
Hogs, indeed!
Mr. Goudy, do you have any more questions?
None that I'll get a straight answer to. I'm finished with him.
-You're dismissed, Mr. Cogburn.
-Call the next witness!
Mr. Redmon points out a 'trick' used by lawyers to discredit witnesses. The expert witness can explain, either in the answer or in recross exam by his attorney, the fact that measurement values always contain some error and the adjusted value is the one needed by the court in order to understand the interrelationship of the whole, not the 'raw' data dealing with any apecific part of the information presented in the survey.
When you 'know' what you are doing, it is easy to frame an explaination.
Richard Schaut
and the values shown on his or her map are simply very good estimates based upon measurements
I like that: maybe instead of (M) we should label a line with (VGE);-) !
it seems that there are three kinds of surveyors
Those that understand the meaning of numbers, and those that don't.............
Throwing Cats
into a room full of Dogs. Did you just want to hear all the barking, or is there a point to all this?
A measurement could be defined as the best estimate available from the information gathered by taking observations of distances, angles, and GPS coordinates, and/or vectors. Your best estimate with all things considered is what you should report for comparison to the record values.
Adjusting the traverse is also applying information-the knowledge that in reality it does close. The adjustment by any reasonable procedure provides a better estimate of the corner positions than the unadjusted traverse values. It is more likely that small errors occurred throughout the traverse than all of the error occurring in the last leg.
Using least squares with good estimates of the likely angle, distance, and centering errors provides a better estimate than simpler adjustment procedures. Under a set of mostly reasonable assumptions, LS provides the best estimates (most likely values) from that observational data.
In Florida...
That threshold could be one least significant digit in the values presented. But you aren't prohibited from showing R=M either when that occurs and that provides the information that your measurement agreed as opposed to being "close enough".
How can you even call it "Measured"?
Most likely, you stood there, collecting data with a GPS reciever, set a couple of random points to tie the mons under canopy. Set up your robot and took a couple of check shots; run it all through your wiz-bang LSA program; everything looks hunkie dory; draft up a map and send it out with an invoice. (at least that's what I do;-) )
Back in the day, a party chief, instrument man and rear chain man/rod man, measured all the angles and distances with a theodolite and steel tape. The priority was, always measure between points on line, if you can't, measure it on an offset and as a last resort, run a random traverse and calculate it.
It's a calculated distance at best.
How can you even call it "Measured"?
Calculated is when you derive a number from other numbers that you were not involved in determining.
How can you even call it "Measured"?
It's a calculated distance at best.
Yes, but it is your calculated data, not record and it most likely will not be a perfect match, unless you are ashamed of the results, show your work, you went through the measuring efforts for a reason. Also having your results in the record reinforces the record position.
jud
How can you even call it "Measured"?
As defined in Ghilani & Wolf's Adjustment Computations what you're describing is an indirect measurement as opposed to a direct measurement.
The real question is:
How can you even call it "Measured" if you don't use a parasol?
How can you even call it "Measured"?
Not only is it unlikely to match record perfectly, it never will match record perfectly. If a line between two monuments is surveyed 100 times, should there be 100 different records of its length even though each survey contains enough uncertainty that the surveyor is just as likely to agree with any of the other 99 records if he measured it again tomorrow?
OK, somebody post the cartoon of beating a dead horse now.