Drones?

Well I have no Idea. But be careful up in the air. Some eagle or hawk or a kid like i use to be takes his kite and goes full dog fighting in the air. One day you will simply have fun flying all around for sure. Everyone is using drones these days. Farmers surveyors the kid down the road. What did you end up going with for hardware and software?

dumb thing just showed up in the office like magic, I have no idea about software, we shall see how it works. I've not had much luck with data from drones, they have always been lacking. But we've got over a 100 acre site hand topo to check it out. If it works.........

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Not all drones are equal. Is it a lidar or image. Is it fixed wing or not. We have one that is used for nothing but inspections on power lines. Its a high speed camera the positioning is not survey quality but is serves the purpose to get up close an personal for good photos of tops of wires transformers for inspection. It has all the safety features so it doesn’t crash into wires etc. we have others for different uses. Get your license to fly. Follow faa rules and state rules. And don’t fly it over @holy-cow house. I remember him stating something about that. If its lidar and you are looking to get elevation data. Understand the way to set ground control points and check points. Also vegetation. I don’t know what terminology they use now days but i say signatures so you can get good data and know what is suspect. If you need to know what signature a certain plant puts off use okra as a guide lol. Very close. I need to get spun up myself on this. I imagine a lots changed since i was doing any lidar from the air in a while. My crew loves it. He only gets a sore but and thumbs when working. Sitting in a truck flying.

It's the age old drone issue. We have about 100 acres of topo: ag land pushing into urban. There is 85 acres of open hay meadow, as usual all the action will be concentrated in the other 15 acres of drainages, ditches, paved and unsurfaced roads, utilities and hard features. So the hand topo is complete, It took 14 hrs more or less. That included the otherwise unnecessary task of setting drone targets. Probably at least 2 hours. So 12 hours for the hand topo and a couple of hours computer time to draw it field to finish. Those 12 hours also included time that would have been spent filling in for the drone survey such as inverts, meeting utility markers, tight locations of tie ins, TBOC, FL, ect locations the drone can't accomplish. Then there are the void areas, bottom of drainages, pipes, culverts, all that stuff.

We will have a nice picture I guess, although the new county 2023 photos are kinda awesome.

We will see, this project is a perfect example of if the drone is useful, I'm doubtful, the computing time, set-up time, field time and void survey time doesn't seem to pencil out on any other projects we've done.

The ability of on the ground GPS usually swamps the capabilities of drones. Unless it's something like a construction/mine survey, then a drone is a no-brainer. We had a client that left us for a drone company and I can't blame them one bit. Open pit mining is perfect for a drone, impossible for boots on the ground surveys to compete.

For 100 acres with 85 of that open natural ground, that's sort of a tossup for sUAS work around here. If mobilization and travel is not an issue (the drone crew is already in the area) and they're just looking to extract a grid of ground points to supplement the topo, and there are not any hoops to jump through with COAs, and the weather forecast is decent...sure, an sUAS flight might beat out a ground topo. But only barely, considering the respective rates and time allotments of field crew vs drone crew and post-processing team.

As @OleManRiver mentioned, not all drones are created equal, but just as important not all drone operators and post-processors are created equal...or I guess make that, adequately trained and experienced. If you don't have qualified personnel performing the work, it's generally going to be a crapshoot, with emphasis on the "crap".

If you do have qualified personnel, you can get very good datasets that merge more or less seamlessly with the boots-on-the-ground topo work, and sometimes can be very cost-efficient.

With a quality LiDAR unit, it's a no-brainer. With typical flight altitudes, you can get ground returns under canopy, curb and gutter breaklines, and clearly identify features that may or may not show up in a higher-AGL manned-aircraft dataset. But it also costs a lot more. There needs to be a good reason to get that much data.

Apparently this site is on a flight path. You can only fly 100' so it's taking lots of time.

Geo Zones will put a damper on your flight plans for sure. That's pretty low for a photo flight. It may have a tough time processing that. I use LiDAR for high vegetation sites and photo for hardscape heavy projects. I like to fly 150'-200' AGL for optimal LiDAR results and 250'-300' AGL for good photo results. Topos can be hit or miss as long as you do some ground truthing with it. But being able to buzz over a large grading site in a matter of minutes and then produce a cut/fill map and volume analysis is the cat's meow.

It's a good thing, there's good people here on this board, that are willing to help you!

I remember, back in the day, I got a lot of excellent responses about GPS, almost instantly!

Good luck, take it one step at as time...

If you haven't already done so, familiarize yourself with the ASPRS standards and apply them.

I've been using UAS photo and LiDAR for about a year now, mostly for the solid waste industry. I treated it similarly to my move to network RTK. I tested it against closed total station surveys. Since you'll be comparing it to field data, in addition to point to point comparisons, run a surface comparison.

Also, make sure to tell every photogrammetrist you meet how easy it is to do their job even with next to no technical knowledge relating to digital photography or aviation. You'll find out quick where you need to focus your studies.

Learning new stuff is awesome!

So, the drone survey was completed, got some nice pictures. Comparing the drone survey surface to the 4-wheeler survey brought up some discrepancies. Imagine that.

Went to the field and got actual rod shots on the 4-wheeler points for a couple of dozen locations. The greatest error between rod and 4-wheeler is .15', basically what I always see, most of them were less than a tenth and many were within hundredths.

The drone survey drifts to about .4', which I would consider not bad for a drone, however, not good enough for this survey.

Lots of drone surveys are just like this, almost good enough, but not quite.

Sounds like we may get a school campus add on next.

Again, we will have hand topo compared to drone surface, I'm guessing the hand topo will be better, this time much better cause it will be a walking one.

Yeah, if you have a decent side by side or ATV setup I think that makes it even harder to make the drone jump. I've got some decades to go in my career so I'm expecting to see the day where drone mapping is considered the conventional way of doing things.

Honestly, I was impressed by the photos and those will be useful for the client.

Where the drone did ok was in open ground, dirt roads, but in the hay meadow, grass, ground cover areas, it struggled.

Horizontally, it also had some issues where there were actual shots on visible points such as water valves. The water valve was visible but slightly shifted in the photo from the rod shots. Checked them the rod shots were good, the photo "just a bit" off.

I chuckled when the drone computer guy showed me the "least square closures" of the drone on the photo control points.

All you gotta say is Least Squares and everyone is happy.

Never mind that the GIS lines are 300' from the fences. 😉

Deliverable quality varies with flight altitude, number of targets, platform positioning (RTK? PPK? GNSS + IMU? Just targets?), and camera quality. If flights were as low as you suggested upthread, that can definitely affect post-processing performance.

Concerning LSA...how else would you suggest performing QC/QA and adjusting a flight to control? (Also - how many targets were control and how many were checks? If they're using them all as control and forcing things to fit, of course the numbers are all going to look good. But that's not a problem with LSA, that's a problem with the operator.)

Generally, for planimetric features over a moderately sized or larger design topo, if the photogrammetry is within a tenth or so of ground truth checks...it's the same. Unless this is a dense downtown urban area with packed-in utilities, a civil design team wouldn't care, or even notice for that matter.

The ASPRS publishes standards and specifications for remote sensing, and they are not quite as simple as "if the surveyor takes an RTK shot and doesn't like it, the data are bad".

For instance, vegetated areas are evaluated differently than non-vegetated areas. The former not being as perfect as the latter is not grounds for declaring photogrammetry insufficient for surveying purposes. It would probably help for someone to review the standards and the methodology for proving them out before declaring that sUAS is somehow "not good enough".

How can you tell? If the features in the photo match the locations from the survey.

That's how photogrammetry has worked since I've been doing it, for some 45 years now.

Least squares statement for the targets doesn't resolve the </font>inaccuracies inherent through the photos. Least squares has a place of course, but I've also seen it used as a "math wash" of poor data. I once asked a senior surveyor how his data was imputed into his organization's GIS files and he said it was sent off to the GIS "guru" and that department used "least squares" to adjust it in "correctly" from historical data. He couldn't have rolled his eyes any harder as he told me. Maybe that's why the parcel polys are so far from the actual property lines.

And I don't really care much about slips in these photos horizontally, it's the vertical that's critical. How much of the 100 acres will have dirt moved? Hard to say, but even if it's 60% that's 60 acres and .4' across 60 acres is a huge volume and cost. Horizontally a few tenths is nothing, vertically it's huge.

Would more targets resolve it? Possibly, but at what cost/benefit to the client?

If it takes more time to panel a project than to hand topo it, then the drone isn't worth it.

There are lots of fresh photos that I can import into any job for a small fee or even free, so the photo itself is nice but of limited value.

I'm also seeing some of my bigger clients nixing their photogrammetry department topos for vehicle scanning, maybe they are seeing improved accuracy. We will see going forward, but the scanning data looks really good so far. What little I've worked with it.

But forward to the next one, we will try it one more time, this time without the airport limits and on a more industrial site, the entire site will be a hand walked topo with the drone as a supplement. Going to try and sell the drone photos to the client as a big deal; sometimes I feel a little like a prostitute.😉

No doubt they'll like it, cause it looks so good. See what I did there?

Wrong tool for the job. Photos work great for hardscape and mowed lawns. You need LiDAR for hayfields and tree canopy.

Or my 4-wheeler 😉

I would try and count up the topos we've done over the years that way but there isn't a chance I could figure out how many, thousands for sure.

100% Correct, drones are great for any surface you can see like dirt, gravel, concrete, etc...but terrible with anything like grass, weeds, brush, etc.... We use them to 1 degree or another on every project we do nowadays with accuracies much higher than the 0.4' mentioned above. It's just another tool in the tool box. Know when to use it when not to.