Quantities on Prairie Dog Piles

while i'm talking out the wrong end in saying this:?ÿ i would think this would be almost the ideal application of drones.

This is a perfect application, assuming a few things....

Before running out and buying a drone for this, make sure you can actually fly at the site. Any decent Surveyor friend who has a legal program should be willing to help walk you through it.

If it's a go learn the basics before you buy. Get a handle on the workflow and what parts you have staff to do. There are literally thousands of suppliers and hundreds of trainers. Use people with verified references. Learn enough to smell any bad stuff being shoveled and sold.?ÿ

Good luck, Tom?ÿ

LiDAR is the tool for this for sure.?ÿ The days of hiking up and down and around piles of material are over, or at least should be. Yea technology!?ÿ?ÿ

Let me rephrase the question. Given a surface that is all the same color and has a surface that looks like a Ski Mogul and using one of these online services that you send them the info and they send you the quantity. Would drone photography alone (no lidar) be sufficient to get an accurate surface?

I am not the one doing this. I don't want to be the one doing this. I am on the outside looking in. I just don't see how the software can pick out enough matching points to accurately represent a surface that has dozens, if not hundreds, of humps about the size of a dump truck bed. I am having this discussion with someone that did not come from a surveying background and thinks that if the computer spits out an answer, then it must be right.

I agree that lidar would work. I agree that scanning would work if you could get in a position to see in each hole. I just don't see that photography alone would do the same thing. I could be wrong, I hope I am.

James

I did a series of piles with about 2 inches of snow on them last year. Nothing but phantom 4pro photos and GCPs. We nailed the groundtruthing points.

Long before drones, before LIDAR, before digital photography even,?ÿ I was involved in photogrammetric mapping of slag piles at Oregon Steel Mill. We maintained ground targets (sprucing them up once a year or so, mainly), the mill had deal with the photogrammetrist to fly it regularly.?ÿ ?ÿ ?ÿThose piles were much larger than those in your picture but roughly the same shape.?ÿ

Was chatting with one of our construction supers this morning about drones. He'd gotten one into the budget for this year, not for mapping purposes but for carrying fishing line across long aerial spans for pulling aerial cables.?ÿSounded great, until they got a quote on the commercial liability insurance and saw the?ÿFAA's commercial drone operator requirements.?ÿ?ÿMust say though that I really don't see a better alternative for computing quantities out of piles of material like your prairie dog colony.

The operators requirements are not onerous at all. It was actuslly kind of fun. The insurance is also very reasonable even when underwritten by the big guys.

There are a lot of outfits that set you up with everything you need. Some are very good, some are horrible. We used Aerotas and it fit our needs well...

Lidar and drones would definitely be the way to go when measuring "prairie dog piles".

I am by no means any sort of expert?ÿwith in situ materials measurement, but I have a great amount of experience.?ÿ I?ÿinventoried the materials?ÿmonthly?ÿfor an asphalt producer with several plants for a good ten years.?ÿ I have tried (generally successfully) every kind of procedure known to man (and a few unknown) to estimate quantities with the help of proper measurements and tools.?ÿ Your "prairie dog piles"?ÿis a good example of a good "head scratcher" as to how to get it done.

I do remember a similar mess at?ÿon an airport job.?ÿ The quarry ran 18 wheel loads of rock for three days and left a five acre area of "prairie dog piles".?ÿ Suddenly everyone needed to know the cubic yardage of the mess even though we had a good stack of tickets from the scales.?ÿ I had a day to determine the volume of the mess.?ÿ

I took a number of samples an determined the average moisture content in the lab.?ÿ I then counted (eenie-meenie-minie-moe) on my fingers the number of "piles".?ÿ Since I had the scales tickets (most of them anyway....rock haulers are not a particularly detail oriented bunch of folks) I verified the number of loads.?ÿ I averaged the tonnage for all the loads and backed into a volume using the average moisture content.?ÿ I then had a pretty good "swag" as to the volume of each load.

Since the aggregate material was to be placed on well-graded modified subgrade we had a good idea of how much it would ultimately take to build the rock grade.?ÿ If I remember correctly my measurements were within 3% of what we actually had on hand.?ÿ None of the "piles" were actually 'surveyed' so to speak, but a good volume was derived using my noggin. ?ÿ

Would it be cost effective to have a decent equipment operator shape that mess ('08 photo) ? Thinking here, that if you shaped that quantity once, it would outweigh the average daily haul that changes it over shorter periods.?ÿ

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edit: you could always rtk the top of every pile, beforehand, to tally the number of hauls for a tossing-runes-and-chickenbones estimate.

Posted by: R.J. Schneider

Would it be cost effective to have a decent equipment operator shape that mess ('08 photo) ? Thinking here, that if you shaped that quantity once, it would outweigh the average daily haul that changes it over shorter periods.?ÿ

I think you are correct. That's what I would try and arrange.

To go back to the original question a UAV should be able to get good results on that sort of surface, depending on the software you use. Photoscan would have no problems. Adequate ground control to provide checks would give you confidence in the results.

?ÿA couple of years ago we did a demonstration for a local water company, flying a reservoir and the downstream slopes. (See pages 23-25

https://www.geomatics-world.co.uk/magazine/september-october-2017

for a general description of the demo.)

From the photography we contoured the downstream fields at 5cm. intervals and found, to our surprise a huge number of circular shapes. Looking at the photography we realised that some of the fields were full of molehills, but there were far more circles than molehills. On revisiting the site we realised that the "invisible" circles were actually last years molehills, which by now were grass covered. General size of the molehills was around 30cm. across, flying height was around 350 ft.

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You could fly it and generate quantities for less than the cost of a machine and operator for a day.

Posted by: R.J. Schneider

Would it be cost effective to have a decent equipment operator shape that mess ('08 photo) ? Thinking here, that if you shaped that quantity once, it would outweigh the average daily haul that changes it over shorter periods.?ÿ

Absolutely, and if I had an operator that worked for me, that is exactly what would have happened. You can't put a dozer on a pile because the tracks would potentially change the gradation of the rock. A rubber tired loader would work with a good operator that knows the limit of getting close to the edge.

Getting that to happen was always the problem and I didn't have enough stroke to make it happen.

James

I guess maybe I am just too much of a skeptic. This is being done with a minimum of ground control and no checks. I have no control over how it is done and the checks that go into it.

Chris said above "Adequate ground control to provide checks would give you confidence in the results."

What I would like to do is fly one of these prairie dog piles. Then paint a red + on top of the humps and in the valleys, and then fly it again. Comparing those two would satisfy my curiosity and skepticism.

Thanks for the help. I feel better about it now.

James