@steinhoff maybe you know this. Why did alta only choose the semi major axis and not both. Some states require both as i have read different state standards. I understand that the semi major is the largest error. It just seems to be more technically correct it would have been both. I have only been back in private practice for a little while so all of the new alta standards are just that new. When i was in private practice before it was before the year 2000 so it was alta acsm standards I believe back in the 90??s since you seem to be on top of all this and i am playing catch up have you heard why. ?ÿI have heard and read some older standards heard different things like they were calling it relative positional accuracy for a bit and around 2011 maybe they switched to relative precision etc.
write the elevations for TBMs to 3 decimal places. When I pointed out that we were starting from a BM that was only accurate to 2 decimal places
The procedure makes perfect sense to me although he couldn't explain it. If you round off a bunch of intermediate results, the random error in the final answer will be larger. Every rounding adds error and needs to be kept to an acceptable level. Maintaining an extra digit along the way minimized this accumulation of random errors.
If you round off a bunch of intermediate results, the random error in the final answer will be larger. Every rounding adds error and needs to be kept to an acceptable level. Maintaining an extra digit along the way minimized this accumulation of random errors.
There are two elements to a problem of this sort. The new measurements may be of a precision that bears carrying 3 decimals. But if the benchmark you start off only bears 2, the final result cannot be better than that.
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Starnet also allowed for taping if I remember correctly in the network adjustment.
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That's very interesting. Unfortunately, taping has gone the way of the dodo.
It's a very useful feature when you have 2 points very close together and you want to preserve that relationship.
Why did alta only choose the semi major axis and not both.
Because the semi-major is the larger.
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@norman-oklahoma yes it??s the larger. ?ÿOne state requires both axis to be used in order to compute the relative position precision. I was just wondering if any more details or reasoning was discussed over the years. ?ÿI am sure it is sufficient to make a standard . ?ÿBut the way it is written in the standards leaves some major technical interpretation to be done. Or assumed. On the math part.
My fellow surveyors, while I do agree with you, I do.?ÿ That said, how many legal cases against surveyors do we know of that involve a measurement that is 0.04' off, vs how many legal cases against surveyor do we know of where a surveyor missed an easement or another encumbrance?
Attorneys usually don't like to argue aspects other than what they know.
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Again, I'm not saying the technical requirements do NOT matter, but we sometimes 'strain out the gnat and swallow the camel'.
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Again, I'm not saying the technical requirements do NOT matter, but we sometimes 'strain out the gnat and swallow the camel'.
I'm pretty sure folks certifying that they're adhering to ALTA minimum standards (including the topic being discussed) when they're NOT in compliance is a big deal.
One of the many reasons why surveyors aren't taken seriously in the professional world- a lot of them can't even adhere to the standards required for the survey they're doing. That or they willingly choose not to because it's a standard that they scoff at.
@joe-the-surveyor The value of "standards" or "requirements" can often times be judged by the consequences of not following those standards or requirements. Don't run a red light for example. We recognize the consequences and appropriately do not run red lights. No one likes a rule the they can't understand the significance of. What are the consequences of an ALTA done that only meets RPP of 4cm+5ppm? You can argue it is a rule and therefore must be followed, but it will always be human nature to?ÿ evaluate the consequences of following or not following the rule. I agree straining the gnat but swallowing the camel is not a good way to operate.
Can anyone explain the value of the ALTA RPP being what it is and not twice as stringent or twice as loose?
Why is the current value the sweet spot that avoids those negative consequences that would otherwise occur?
@norman-oklahoma And the third element maybe how you get the extra digit.?ÿ If a level rod is marked in hundredths and you split a bar.?ÿ You could write another digit by estimating which side it's closer to. Or another method is just round to even every time a space or bar is split (theoretically some round down and some up).?ÿ So you have the math of carrying one extra, but also consideration of tools used, then the end reported result appropriate.
More than one way to skin a buck, but shouldn't report it as the pelt of a mouse.
You could write another digit
If it's marked in hundredths and you have good visibility through the scope you should be able to estimate thousandths with a reading accuracy of +/- one thousandth.
@bill93 what was the little slide plate called you could get for the old philly rods to align and direct read the thousandths place. I can??t find it in the cobwebs of my brain. I know on most regular levels not geometry quality but every day levels if you don??t exceed about 300 ft you can do exactly that and interpolate that much easier. A ls i know required the reading to 3 decimal places for all single wire read because he knew they the crew would have to stay around 300ft max distance or they would seriously struggle. Which also helped to cut down on that curvature and refraction at that distance.
what was the little slide plate called
vernier?
If you are doing any serious levelling today, especially where thousandths count, get a digital level to do it. Then start to learn about the other sources of error in a levelling program - the ones you have considered trivial up to now.?ÿ With a digital every one of those thousanths are real.
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@bill93 It was like a brass little plate. Slid up and down. Just like caps to tripod heads it was the first thing to be tossed away or lost. Lol.
