Kent does not suffer fools lightly
> exactly! I'm pretty sure Kent is the one that was just repeatedly called names by a supposed professional. I think he did a fine job of making his point without returning the schoolyard hijinks.
I guess it wasn't me because I ain't a professional. Kent & I actually have something in common. We can both be experts about a subject without actually knowing anything about the topic.
Kent, Give It Up. His Name Is Half Bubble, Enough Said.
Save it for those who want to learn.
Paul in PA
Oh Great!
> Half,
>
> I hope you look for property corners, they way you are looking to try to catch Kent. So far he has backed every point he made with facts logic and proven survey methods, and I would not try to say he puts out low quality survey work when you admitted that the plumb bob method that you are using starts with 0.02 of error.
>
> How can you defend your survey when another surveyor calls you and says I am not matching your work. Once you tell him you started with know error, well lets just hope the fence is the less expensive thing you have to move.
>
> How many samples of error do you use on a transverse?
I can't speak for Half Bubble, and it's been a long time since I used the dist-o-line with a plumb-bob but......
A plumb bob always points down. A prism pole has to be properly adjusted to point down.
I've had to yell at people chipping ice and digging holes with my prism pole. I've seen it sliding down a hill and smacking into a tree and rattling in the back of an open pickup.
Oh Great!
Perry,
I know what you mean, the crew thinks the range pole is, a Swiss army knife. I have seen plenty of guys trying to "force it plumb" against a fence or a culvert. Or as shovel or to help jump a ditch.
I have also seen plenty of guys using a plumb bob as a hammer and or with knots in the string.
We have one of those range pole calibration jigs on the wall, only takes a moment to check the pole, and its alot faster and easier than the old door frame method.
I am not against Half Bubble's method, I just dont like the idea of starting a setup with known error, because it is faster and I dont have to carry as much equipment. If you have a short back site the error never gets better. Now if something is over the property a tenth, well its going to be a long night.
Yes I know my instrument has error in it, but it is calibrated and the range pole is checked more than once a week.
I have used the plumb bob to set up the total station and level before, I prefer the optical site, if I was in the field and my tribach was dropped and the optical site was broken, yes I would use the plumb bob to set the instrument up.
The prism pole always points down, it has to be adjusted so the top is plumb.
Oh Great!
> Half,
>
> I hope you look for property corners, they way you are looking to try to catch Kent. So far he has backed every point he made with facts logic and proven survey methods, and I would not try to say he puts out low quality survey work when you admitted that the plumb bob method that you are using starts with 0.02 of error.
Kent's facts are statements, and as Mark Twain said, "sayin' so don't make it so."
His logic is spurious, and his proven survey methods have as much error as they always have. What makes his work good is attention to detail and a dogged determination to avoid trying anything new.
If you think 0.02' "known error" is bad you might try running one of your traverses through some kind of least squares. Star*net has a 10 station demo, Columbus has a 12 station demo and a new cloud-based service that is $1 to $19/month and can be run from a web browser. I am fairly sure you would find that 0.02' is a lot smaller than what the average "proven survey methods" push around. Every survey has error. If you cannot show what it is via statistics, then it is probably much larger than you think.
I will admit that the EDM I use can only measure to about 0.20'
Fortunately it takes a few thousand extra shots automagically, runs a least squares on it, and gives a least count read to three decimals with specified one-sigma standard error of about 0.006'. Most people don't notice this because it does it all with one push of the button.
Likewise, our GPS can only get a position that is good to a tenth, even after a bunch of least squares and differential corrections. What if some surveyor doesn't agree with me? Now what? Throw it out?
> How can you defend your survey when another surveyor calls you and says I am not matching your work. Once you tell him you started with know error, well lets just hope the fence is the less expensive thing you have to move.
Has to do with the amount of research you do and the amount of evidence you dig up. The more you dig up the more likely you will find the discrepancies. If you are the most thorough, there will be no surprises.
If I know what my error is, and the other surveyor doesn't, who do you suppose is more likely to have the larger error? Why?
>
> How many samples of error do you use on a transverse?
I use all the redundancy I can. I haven't done a pure loop traverse with sideshots in years, though. Closed figures and cross ties, yes.
Kent does not suffer fools lightly
> exactly! I'm pretty sure Kent is the one that was just repeatedly called names by a supposed professional. I think he did a fine job of making his point without returning the schoolyard hijinks.
:good:
Is it too late
To ask how you hold a mini with a prism and press measure on the data collector at the same time?
Is it too late
This week I'm using a full size Leica -34.5mm glass. It is upside-down and the plumb bob string is ties thru that little sighting slot in the orange plastic housing.
I hold the glass by the housing as plumb over the glass as I can. I started out with a nice leica-to-5/8's threaded adapter and drilled a hole for the string, so the prism was down-side-down, but this made it too top heavy to hold plumb, and seemed to make for more centering error. I wanted to get the string attachment closer to the center of the glass, that's how I wound up with it how it is now. A mini would probably work better.
I hit the button on the DC with the thumb on my other hand. It's a robot, so those newfangled radio waves take care of the issue of otherwise having to be two places at once.
No, its not too late
I was wondering the same thing. I had just chalked it up to HB being a real steady hand.
Tried the same thing hugging the top of an eight foot fence like a Koala bear, holding the prism and jig steady in one hand with elbow locked into the crook of the fence, and the other hand feeling the buttons over to the measure button. Settled down the bob, took in a full breath and let half out, nice and easy depressed the button. Hats off to HB, I couldn't do that with any speed or accuracy.
Oh Great reads!
Thanks for the vote of confidence, Gavin.
I will certainly take you up on the book loan next time I get north of Green Lake. 😉
well, I knew this
I'll post a star*net report or portion thereof next chance I get.
Might take a week or two.
No, its its too late
My hands aren't all that steady. I am surprised that anything is better than a tenth.
My theory is that it works because of the Leica ATR. It has to shoot the glass long enough to get a weighted mean for the EDM, so the ATR is probably also getting a weighted mean of the H and Z.
The first time I did a whole job, control and all, with a handheld rod, I was sure it was never going to be better than a tenth and compound like crazy. Yet, with 2D & 2R it was as good as a bipod.
I try to run a robot like it was shooting a rifle: breath, relax, aim, squeeze, surprise. It is a heck of a long lock time, though. And it's a surprise, you press the button and you wiggle around for a few moments thinking "this isn't gonna work" and the eventually the robot beeps that it got the shot and hopefully doesn't complain that the shot is out of the averaging limit.
The machine reads your intent: if your intent to keep plumb over the point is strong, even if you wobble, the machine will take the weighted mean of your intent. Turns out that is a pretty darn good measurement to the point.
(Yeah, I know the machine is just doing math, and cannot possibly give a squat about intent. The end result is the same.)
well, I knew this
I know TP Stephens says people should "beware" me, but I don't even know how you set up a prism with just a plumb bob. Are you using the string for line, then getting a distance separately? How do you make sure the prism then is over the point of the monument? I'm genuinely curious. I suppose if you have a two or three man crew you can do it this way, but I've been solo since 2005. I don't have time to play around with things that don't get the job done by one person.
well, I knew this
This is solo robotics also. The robot tracks the prism, not the string. That's kinda the point.
What can one gimpy scarecrow carry and make a topo or a site plan or recover monuments?
You could do the same thing with a crew of 2 or more and a manual instrument. I would sure like to find a crew that could work to spec with plumb bobs and handheld rods.
Kent, and others, my apologies
> > exactly! I'm pretty sure Kent is the one that was just repeatedly called names by a supposed professional. I think he did a fine job of making his point without returning the schoolyard hijinks.
>
i got out of line. i will endeavor to keep it together in the future
Andy - Distoline (sp?)
> I know TP Stephens says people should "beware" me, but I don't even know how you set up a prism with just a plumb bob. Are you using the string for line, then getting a distance separately? How do you make sure the prism then is over the point of the monument? I'm genuinely curious. I suppose if you have a two or three man crew you can do it this way, but I've been solo since 2005. I don't have time to play around with things that don't get the job done by one person.
They make a rig called a distaline (sp?) which has a peanut prism with a plumbob and string. There is a small ping-pong sized ball w/ gimbals on the top that you hold onto and hang the plum bob right over the point. I have one somewhere.
Andy - Distoline (sp?)
The Dist-A-Line seemed like a neat gadget when I first saw it advertised years ago, though I always wondered if locking the string would prove to be a hassle. In any case, I never did get around to buying one, and I don't think I'd have much use for it these days.
well, I knew this
ok, so bear with me for another minute. How do you know you are holding the prism assembly in all roll/tilt/yaw combinations, pointed toward the robot, plumbed over the point, AND run the robot? is it voice activated? 😉
even if the prism has a small bubble on it, seems like those aren't all that particular, and you still have to hold every thing steady AND THEN somehow direct the robot when you are ready for the shot?
I use a Geodimeter 650 bergstrand, generally with the 360 prism that needs battery power (through the rod) . the DC is mounted on the bracket with the radio on the rod. Why would I go through all the trouble to basically get rid of the ROD that ties all those parts together in a nice lightweight unit?? Just to say I can do it?
Wait.. to make it even worse, if you need to collect TOPO with this bob/prism setup, do you then measure and change your prism height with every shot?
I'm missing something here.
well, I knew this
> ok, so bear with me for another minute. How do you know you are holding the prism assembly in all roll/tilt/yaw combinations, pointed toward the robot, plumbed over the point, AND run the robot? is it voice activated? 😉
>
> even if the prism has a small bubble on it, seems like those aren't all that particular, and you still have to hold every thing steady AND THEN somehow direct the robot when you are ready for the shot?
>
> I use a Geodimeter 650 bergstrand, generally with the 360 prism that needs battery power (through the rod) . the DC is mounted on the bracket with the radio on the rod. Why would I go through all the trouble to basically get rid of the ROD that ties all those parts together in a nice lightweight unit?? Just to say I can do it?
>
>
> Wait.. to make it even worse, if you need to collect TOPO with this bob/prism setup, do you then measure and change your prism height with every shot?
>
>
> I'm missing something here.
It took a few tries to get the roll/tilt/yaw minimized (as mentioned above). I've got the string tied thru the sight on a Leica prism, and fortunately that sight is pretty much on the plumb line. I just try to hold it with the pad of my middle finger as close to the center of gravity as I can. There may be better prisms or holders, maybe even purpose built.
The only use of the knowledge for you would be if someday you had to use a helper and a manual instrument, you'd know that it could be done. If the Geodimeter works for you, run with it.
I would like my rig to work for me in a wider range of situations, hence the experiments.
So far the plumb bob tires me out faster than the rod to work with, and I miss being able to raise the rod to 7' sometimes.
I tested the plumb bob at first on some known adjusted control. I 3D free stationed the instrument setup from that control & shot the same control with the plumb bob a goodly number of times in both faces. Including comparing shots on the control for vertical comparison with the calibrated rod I usually use, to get the "height" of the glass on the fixed length plumb bob string. When looked at in terms of the differences on the data collector, and again with least squares, the differences of the individual shots were hanging around 0.05' and the averages after 2D&R were 0.015'-0.02' from the calc control. That was better than I expected and it was good enough for me to decide to pursue it for a while. I have tested it a few times since, either with star*net or just with the data collector. In star*net, with all the other standard errors unchanged from the same glass on a rod, I found I had to open up the centering error of the target-on-bob to 0.02' in horizontal and 0.04' in vertical and everything else fit fine. That tells me that I am keeping the plumb bob over those control points roughly that well. I wouldn't use it in place of a level loop, but the verticals would compare to trig traverse where you measure up with a pocket tape.
I am positive that anyone who thinks 0.02' of centering error is a large error does not know, in any kind of defensible way, what kind of error their own measurement system & procedures are pushing around. I know some guys who shoot a Leica glass but have it set as a -30mm offset in their data collector. So they get 4.5mm somewhere at every setup they mix in that glass. Doesn't bother them in the slightest, because everything they do is "just retracing", so if your measurements match the record within the legal limit (half a foot here), don't report anything different. Maybe this is what Perry is mentioning above, that hitting the known monuments within tolerance is a good enough check for some. It certainly seems to be the community standard in a lot of places, and I say that without any sort of judgement call, because I realize that it is only in the last few years that we have such great technology.
No, its not too late
Two lath and a prism pole. Easy to wrap up with one hand while on the move and once you get the feel and hang of it, you'll be entering descriptors with one hand and holding the prism pole steady without even having to monitor it.
Get the feel for it. Once you do you'll laugh at the idea of bi-pods, and learn their are a thousand uses for those same lath. If someone starts a thread on laths we can cover all that.