I have a project that requires measuring very large stockpile volumes. Measuring from over head with some type of UAV appears to be the way to go. I have virtually no practical experience with UAVs. What do you guys think might be the best approach, purchasing a UAV and learning to use it, subcontracting the service, etc.?
Sub it out. Have real airplane pilot 'fly' the site with a UVA on a routine basis. I think you will find the cost affordable.
@oldpacer Agree... Sub it out. Get an understanding of the workflow before jumping in. Once you get a feel for it, you can decide if you want to purchase.
Maybe have the sub do the flying and data collection and you do the control part. That way it's collaborative and it's part of the learning process.
Do you have the ground before the stockpile was created?
I'd also sub it out for the field/data collection portion only, and I would at least go to the field the first day to see the workflow. The process is simple and the drone takes care of the rest in a couple of minutes, depending how many stockpiles there are.
Besides that, it would be good to have each stockpile sparsely located and on a relatively flat surface without any grass surrounding them (hopefully!). This will ensure a much better triangulation and 3D reproduction in the computer.
How many stockpiles and how big are you talking?
A million cubic yards or so? Maybe you don't know since it hasn't been measured yet.
I'd lean toward subbing it out like the others say but make sure you go along with them to see how it's done. More importantly, I suggest you watch how they process it. Make note of the software being used and if you have time, you can possibly get a copy of the software and try to duplicate what the sub did, as a learning experience as well as a check of sorts.
Most of the software is pretty easy to use.
Do you have the ground before the stockpile was created?
Been burnt by that, I've assumed a flat plane beneath the stockpile?ÿ & it turned out there was much less gravel because of a grade hump underneath it or a sump condition where there was much more gravel.?ÿ You'd think it doesn't matter much but a small grade difference at the pile's base is much more significant than surveying errors concerning height/slope/shape.
I've surveyed maybe three dozen stockpiles usually under contract on a quarterly basis so the client can bill it and quickly learned I can certify how much +-?ÿ is in the stockpile since last survey but to certify how much total is in the stockpile is a different egg.?ÿ I'll not do it if I haven't surveyed the bare ground or am provided?ÿ with a topo showing it with benchmarks signed by a PLS.
UAVs of course cannot detect OG so are no better than traditional surveying.
Thanks for the input. These stockpiles are not accessible to walk on, but I think I can get on stable enough ground on each side of them to use my reflectorless TS to get shots. In the mean time I will be looking into how a drone setup might work.
I think I can get on stable enough ground on each side of them to use my reflectorless TS to get shots.
A scanning total station will be far, far faster and get you better results. Not that RL is necessarily bad, but if these stockpiles are sufficiently large and your client is looking for relatively accurate (accurately precise?) results, that's what I would use if UAS were off the table.
I would wager that you'd still make more profit over reflectorless even if you had to rent an MS60 or SX12 for a day or two.
@mike-marks I don't have any information on the area of the stockpiles other than they have been cleaned out. No idea how flat the base is after that. How is it that getting a quantity since last survey is much harder than calculating the total of entire stockpile?
@rover83 I might check on a scanning TS. Haven't even considered that. Downside to renting might be the frequency I will need it. The contract states quantities will need to be checked about 10 times thru the duration of the project.
I have a project that requires measuring very large stockpile volumes. Measuring from over head with some type of UAV appears to be the way to go. I have virtually no practical experience with UAVs. What do you guys think might be the best approach, purchasing a UAV and learning to use it, subcontracting the service, etc.?
Calcing volumes 10 times on a single project may be enough of an incentive to get your Part 107 and a Drone. You could purchase a $1500 DJI P4 Pro 2.0 and use many ground control points. Or purchase a $6500 Phantom P4RTK with a few checkpoints. Someone like myself can teach/ help you with setup and post-processing. Getting your FAA Part 107 in a timely manner may be your biggest hurdle.
@leegreen Thanks, Lee. At this point I have only bid the project. If I knew it was mine I'd jump on the FAA Part 107 right away. I was just reading thru the remotepilot101 site. Do you recommend a particular training service for Part 107?
How is it that getting a quantity since last survey is much harder than calculating the total of entire stockpile?
I think he was saying it is the other way around. To get a change in quantity takes before and after surveys.?ÿ To get the total quantity you have to either have measured the base before the material was piled, or else assume a flat surface. He was saying he wouldn't assume.
Interested to know if anyone has made a results comparison between UAV photogrammetry, lidar and conventional TS computations? I know from experience that the UAV photogrammetry is less reliable of the 3 methods when I was able to compare a previous client's results using UAVP and my lidar volume computation. But that was more than 5 years ago. Maybe camera and UAV position recording have improved since then??ÿ
