We need you to lay out a grid for a microgravity survey next week.?ÿ But its in a school playground so no stakes only paint marks on the grass.?ÿ And the points that fall on asphalt, no paint only chalk.?ÿ
Nineteen days later (the wettest year on record)...the MG guys cant find the marks, they washed away. Can you come out and remark them tomorrow?
Oh, and even though the sketch we gave you shows a 20 x 20 grid - we really need a 10 x 10 grid.?ÿ So while you're remarking the 109 points, how about setting another 280.?ÿ
Sure, we can.?ÿ BUT the price just doubled.
Andy
Sure, we can.?ÿ BUT the price just doubled.
Andy
"Client" is in house and has a title that rhymes with Wice Fresident?ÿ
Respect to you for writing under your own name and still calling out a fellow VP?ÿWF at your company as a moron.?ÿ On behalf of all of us who write under pseudonyms, I tip my hat.
Want me to come help with my Hoppy Transit? ??ÿ
Want me to come help with my Hoppy Transit? ??ÿ
Just the tool for the job
Respect to you for writing under your own name and still calling out a fellow
VP?ÿWF at your company as a moron.?ÿ On behalf of all of us who write under pseudonyms, I tip my hat.
Actually James Fleming is a pseudonym; ironically my birth certificate reads Frozen North?ÿ ?ÿ
First of all, I say, Well That??s Fantastic!
Then I say, what in Hell is a microgravity survey, and why is it in a playground?
It does sound a little bit fun to me.
I once laid out a 10x10 microgravity grid but then my Dad got a job.
Sure, we can.?ÿ BUT the price just doubled.
Andy
"Client" is in house and has a title that rhymes with Wice Fresident?ÿ
I'm guessing maybe this was pro-bono in the first place? If so, no good deed ever goes unpunished.?ÿ Not paying for it anyway, no appreciation of the cost.?ÿ
My first taste of surveying was on a crew doing control for a gravity survey. But that was a mineral exploration gig in the Yukon Territory.?ÿ Whatever in the world are you surveying gravity in a schoolyard for?
BTW, the cost doesn't double - double would be just for restaking on a reasonable schedule. Overnight service is more. And then staking?ÿ 3x more points is triple. So its a bargain at?ÿ quadruple.?ÿ?ÿ
?ÿ
Hope they plan on doing it at night, when the traffic and kids aren't there.........hate to see that noise floor.....yikes.
How do they build instruments sensitive enough for microgravity measurements? ?ÿ A picture showed a very portable instrument.
You must need precise elevations or a very level surface for the measurement points to account for the variation of earth gravity with height?
In a quick search I was inundated with articles about near-zero-g effects in space.?ÿ I did find a few pages about using it for subsurface exploration but nothing on the technology.
http://apexgeoservices.ie/microgravity/
https://www.keele.ac.uk/geophysics/microgravity/
https://mundellassociates.com/services/geophysics/techniques/microgravity/
How to stake 400 points on a 10'x 10' grid
- Using the gun, or RTK, stake out 100' grid. For a 200' x 200' grid that's 9 points.
- Stretch 100' rag tape between 100' grid points. Using the tape for line mark, with paint or chalk, every 10' along the tape.
- ?ÿUsing the 10' points thus marked, repeat step 2 until grid is fully marked.?ÿ
- Discard paint soaked rag tape.
Also works for laying out 500 trees quickly and cheaply.
How do they build instruments sensitive enough for microgravity measurements? ?ÿ A picture showed a very portable instrument.
You must need precise elevations or a very level surface for the measurement points to account for the variation of earth gravity with height?
In a quick search I was inundated with articles about near-zero-g effects in space.?ÿ I did find a few pages about using it for subsurface exploration but nothing on the technology.
http://apexgeoservices.ie/microgravity/
https://www.keele.ac.uk/geophysics/microgravity/
https://mundellassociates.com/services/geophysics/techniques/microgravity/
The level surface issue is resolved by the instrument itself, set in place and leveled either by a Hooman, and more accurately and precisely by the compooters. ?ÿ 😉
Check out the Micro-G Lacoste site.?ÿ Spent thousands of hours with the CG-5s and the earlier L&R meters.?ÿ Great fun, and humbling too.
I wasn't referring to leveling (or plumbing) of the instrument, but accounting for terrain.?ÿ?ÿ The typical vertical gradient is something like 300 uGal/meter, and the CG-6 advertises 5 uGal repeatability, so you would want 1- or 2-cm elevation information to get maximum information out of the instrument. The video mentions GPS, but is a quick GPS reading good enough to correct for terrain?
Or do they measure at two different heights to get the gradient, and don't care so much about what it reads at one of those heights as they do about a vertical difference?
Or am I still too ignorant of how gravity works?
Oh, and even though the sketch we gave you shows a 20 x 20 grid - we really need a 10 x 10 grid.?ÿ So while you're remarking the 109 points, how about setting another 280.?ÿ
A?ÿ 10x10 grid is 100 points, a 20x20 is 400 points, a change in scope so quadruple your fee.?ÿ
I wasn't referring to leveling (or plumbing) of the instrument, but accounting for terrain.?ÿ?ÿ The typical vertical gradient is something like 300 uGal/meter, and the CG-6 advertises 5 uGal repeatability, so you would want 1- or 2-cm elevation information to get maximum information out of the instrument. The video mentions GPS, but is a quick GPS reading good enough to correct for terrain?
Or do they measure at two different heights to get the gradient, and don't care so much about what it reads at one of those heights as they do about a vertical difference?
Or am I still too ignorant of how gravity works?
Duly noted, It's a pretty detailed matrix of conditions actually.?ÿ The vertical is the most important part of gravity. Regional effects like say, being within 50-100m of a rising vertical wall of rock, or back from the same cliff, or between the walls of a canyon etc have a lot of effect too.?ÿ We used differential survey grade GPS tied to absolute gravity stations that we would occupy for a day or so building networks to validate the vertical, then run our projects in loops just like a land survey. It was gravity that actually directed me into land surveying.
We used RTK when we could, and collected static for all the base verification networks prior to running the RTK.?ÿ I shudder at the thought of having to run level loops across the deserts of Nevada Utah etc to do the same work, like they used to do before GPS.
Sorry for the thread Hijack?ÿ "Frozen Fleming", keep us posted on how they get their points laid out, and if the results actually present the answers they were after.
Oh, and even though the sketch we gave you shows a 20 x 20 grid - we really need a 10 x 10 grid.?ÿ So while you're remarking the 109 points, how about setting another 280.?ÿ
A?ÿ 10x10 grid is 100 points, a 20x20 is 400 points, a change in scope so quadruple your fee.?ÿ
The logic is good for some situations, but the numbers aren't right for this project.?ÿ
If they are talking about 20x20 being densified to 10x10 that must be the spacing in feet or meters and not a point count or an indication of the overall project size.?ÿ To have 109 points or 109+280=389, prime numbers, it must not be a completely rectangular area.?ÿ Without knowing the shape you can't exactly compute the count for densification.?ÿ Mr. Fleming seems to have already computed that.
The more rain the better.
All the depressions will be full of water.
Easy Peasey..........lol
