Owning a drone does not make you a surveyor or photogrammetrist.

[BigAl07]

Here is a good read for any/all of us but especially for those who are "doing it for hire" . . .

Owning a drone does not make you a surveyor or photogrammetrist.

Owning a drone does not make you a surveyor or photogrammetrist. A rant by the president of J.R. Canadian Mapping Ltd.

 

[aerialimagery]

I see the point of this article, but let's say all you do use the Maps Made Easy program and process with no ground control points, etc. How good is that data and isn't there a place for it even if it's not up to par with real surveying and photogrammetry?

 

[BigAl07]

I see the point of this article, but let's say all you do use the Maps Made Easy program and process with no ground control points, etc. How good is that data and isn't there a place for it even if it's not up to par with real surveying and photogrammetry?

That fully depends on the client and what type of data and accuracy they are looking for. Without the accuracy you're just making "neat" pictures IMHO.

 

[Outta Control]

This is what I faced on my last gig.

I look at myself as a data collector for the certified, licensed surveyor.

If any drone mapping is to be done with a stamp of approval. That surveyor will be near to help guide me to get his information.

 

[flockshot]

Technology challenging the statuesque. Who could have seen that coming?

 

[UAV_Mapper]

Almost all these pop-ups advertise DEM creation on their websites. When I have visited their websites and look at the samples provided they are usually digital surface models not elevation models. Not only do these pop-ups not know what they are doing they often do not even know the names of the products they are offering.

I mean, I can't blame them when there is no "official" definition in scientific literature and even the pros can't seem to agree.

Digital elevation model - Wikipedia
What is the difference between DEM, DSM and DTM?
DEM versus DTM versus DSM

With that said, I agree with the underlying sentiment of the article and can sympathize with his struggle to educate his clients as to what separates his professional services from a "pop-up". Every commercial pilot has come up against this, regardless of the type of work that we perform, be it videography, photography, surveying, or mapping. It's the Wild West at the moment, and when the dust settles, we'll be left with those of us that can produce a quality product and accurate data.

I feel the same way as the author when it comes to 3rd party and cloud software, but the client doesn't know what they're getting or if it's any good. There needs to be a vetting process and it should start with certification from a State Board or ASPRS. It has been pointed out before, but there are some states where you can't even sell an orthomosaic without a PLS stamp on it. I'm certain that enforcement is a difficult thing to do, but unless we all help to protect our turf, the streets will be overrun by bad data and bad practices. Through education and certification, I think we can build a better reputation and product for the future.

 

[UAV_Mapper]

use the Maps Made Easy program and process with no ground control points

Without checks or control, you're at the mercy of the on-board, recreational-grade GPS for location information. That data can easily be off in the horizontal by tens of meters and in the vertical by up to a hundred meters. The GPS may be reasonably good relative to itself, but can be off in the absolute, real-world location. (Of course, the more you talk to a geodesist, the less confident you become that anyone knows where anything is, in an absolute sense...)

Yes, there is some value in that, like, for volumes, general grading, and places where you don't need to match existing topographic elevations, but it can be dangerous to stir that data in with other topographic information. Even when a client says that they don't care about the accuracy, you still have to be careful because you never know where that map is going to wander once it leaves your control. The next thing you know is that it's being used for subdivision planning and you're getting sued because all of the sewer lines are flowing uphill.

 

[R.Perry]

When I do mapping all I"m doing is collecting the data, it is then sent to our corporate for processing, Our corporate office sets all the overlaps and conditions that must be met during mapping. One thing that is very obvious is that a map from one month can be overlaid with other months and the mapping track is identical, flight path, pictures taken, are all exactly the same. So it sounds like the GPS system is working pretty well unless I'm missing something.
The drone to me just seems to be a very good tool for mapping, as for someone doing mapping and attempting to process the data that doesn't know what their doing the article makes some good points. I also see it a little like the helo pilots getting worried about losing work to drones, but I may be wrong.

 

[UAV_Mapper]

One thing that is very obvious is that a map from one month can be overlaid with other months and the mapping track is identical, flight path, pictures taken, are all exactly the same.

Are you comparing maps that have been post-processed and have been aligned using ground control or some other georeferencing technique? I would hope that they would align and look the same!

The question was "How good is that data" when it hasn't been corrected and that's what I was referring to. I think we're all familiar with handheld GPS units and we take their accuracy (especially the vertical) with a grain of salt. These are the same receivers that are in the UAVs, unless you have a really expensive one, so you're looking at meters of error in the horizontal and dozens of meters in the vertical. Here's a table that shows the accuracies when you have a complete GCP set and when you take them all away. When you have 0 GCPs, this project showed 2-4 feet of error in the horizontal and up to 62' of error in the vertical. Those values can swing wildly, depending on the satellite configuration and other factors. I've seen "pop-ups" fly overlapping missions hours or days apart and the satellite configuration changed enough to cause a 90-foot vertical change in where the drone thought it was. When they tried to compile the data, they didn't give the software enough "wiggle room" to correct for that and the point cloud had huge steps where the missions crossed. The point is that you can't trust the on-board GPS for anything other than relative values, at that time, and the way that data is collected is very important to the resulting maps.

Take the time to get yourself familiar with how your data collection can affect the final product and how accuracies are generated:
How Accurate is My Map?
How accurate is your drone survey? Everything you need to know.

 

[R.Perry]

Are you comparing maps that have been post-processed and have been aligned using ground control or some other georeferencing technique? I would hope that they would align and look the same!

The question was "How good is that data" when it hasn't been corrected and that's what I was referring to. I think we're all familiar with handheld GPS units and we take their accuracy (especially the vertical) with a grain of salt. These are the same receivers that are in the UAVs, unless you have a really expensive one, so you're looking at meters of error in the horizontal and dozens of meters in the vertical. Here's a table that shows the accuracies when you have a complete GCP set and when you take them all away. When you have 0 GCPs, this project showed 2-4 feet of error in the horizontal and up to 62' of error in the vertical. Those values can swing wildly, depending on the satellite configuration and other factors. I've seen "pop-ups" fly overlapping missions hours or days apart and the satellite configuration changed enough to cause a 90-foot vertical change in where the drone thought it was. When they tried to compile the data, they didn't give the software enough "wiggle room" to correct for that and the point cloud had huge steps where the missions crossed. The point is that you can't trust the on-board GPS for anything other than relative values, at that time, and the way that data is collected is very important to the resulting maps.

Take the time to get yourself familiar with how your data collection can affect the final product and how accuracies are generated:
How Accurate is My Map?
How accurate is your drone survey? Everything you need to know.

Please correct me if I"m wrong, but I use the exact same programmed mapping each month, the mapping is done at 300 feet, does 147 acres, and returns 606 pictures. If what you are saying is correct shouldn't I be getting a different picture count each month if my vertical (altitude) isn't accurate each month, also if the horizontal is off wouldn't the pictures from one month to the next be off?
I"m not a surveyor, I'm not even a construction person, what I do know is the engineers at the job site rave about how good the mapping is each month. Here again, we aren't surveying the job site but documenting the progress of construction and that includes how much dirt was moved each month since they are still doing a great deal of excavation.
I do know the surveyors on the job site does use or at least review the mapping each month, I've never had feedback from them, but I will be asking them this week.

 

[embayweather]

Being surveyor or a photogrammetrist does not make you a drone pilot. That is why we can work in harmony together to get the best results for the client.

 

[LUIS MARTINEZ]

I see the point of this article, but let's say all you do use the Maps Made Easy program and process with no ground control points, etc. How good is that data and isn't there a place for it even if it's not up to par with real surveying and photogrammetry?

The key issue is what the customer wants AND droners passing themselves as surveyors (a licensed profession) or providing "survey quality" imaging w/o the foggiest idea what that means.

Two years ago, out of curiosity, I completed an introduction to surveying course at a local college. I am now officially aware and declare how ignorant I was as to the topic and I'd never presume to know anything about surveying, ever! Not in a million years would I ever utter the term "survey" in my work. I do a lot of construction work (geomaps and panoramas) customers use to monitor progress. The companies utilize licensed surveyors on site before the first shovel is turned. There is room for non-surveyor drone work in construction, must know our limits of expertise. Licensed surveyors go through years of training and apprenticeship to get their licenses.

Are surveyors using drones in the $50-$70K range in their work? Yes, they understand the value of drones and their limitations. Some are even cheaper.

"...isn't there a place for it even if it's not up to par with real surveying and photogrammetry?
Can your setup produce centimeter precision? If not then the answer is NO.

 

[aerialimagery]

What if that kind of accuracy isn't needed or desired? I did a photo map of a cemetery for $200. They can use it to make at least approximate measurements. If they don't trust the measurements they get from the map, they have some known measurements on the ground they can use to make adjustments. It serves their purposes anyway. Could they get one centimeter precision for $200? No, and they wouldn't pay it. I don't think it's reasonable to assert that there is no place for it because it's not as accurate as real surveying.

Also, the mapping process generated a very detailed image that was made into a large print and is used for planning.

 

[LUIS MARTINEZ]

What if that kind of accuracy isn't needed or desired? I did a photo map of a cemetery for $200. They can use it to make at least approximate measurements. If they don't trust the measurements they get from the map, they have some known measurements on the ground they can use to make adjustments. It serves their purposes anyway. Could they get one centimeter precision for $200? No, and they wouldn't pay it. I don't think it's reasonable to assert that there is no place for it because it's not as accurate as real surveying.

Also, the mapping process generated a very detailed image that was made into a large print and is used for planning.

Apples and oranges my friend. I do a lot of geomaps for customers like your cemetery. But that is geomapping not surveying in the strictest sense of the definition. If it's making you $$ you are golden.

I began my reply with "The key issue is what the customer wants..."

 

[aerialimagery]

OK, but that's what I meant by "there is a place for it." I didn't mean to imply that it's anything like real surveying.

 

[LUIS MARTINEZ]

We agree, it is not surveying . My pet peeve are guys buying a Phantom and going into the "construction survey" business, w/o any awareness of what any of this means; WGS84, Bench mark, GCP, Datum, Cadastral, total station, POI, and that's just a bit I remember from my intro to surveying class.

 

[UAV_Mapper]

If what you are saying is correct shouldn't I be getting a different picture count each month if my vertical (altitude) isn't accurate each month, also if the horizontal is off wouldn't the pictures from one month to the next be off?

Not really... a Phantom uses the barometer for the altitude settings for a flight, so you'd have to compare the exif data between your flights/photos to see their approximate relation. The horizontal is going to be reasonably close, so I imagine that your mapping area is going to be about the same.

Basically, you need to compare the raw data to see the discrepancies that I'm referring to. When comparing volumes, you can use uncorrected data and get good readings because you're using the relative location data.

 

[R.Perry]

Not really... a Phantom uses the barometer for the altitude settings for a flight, so you'd have to compare the exif data between your flights/photos to see their approximate relation. The horizontal is going to be reasonably close, so I imagine that your mapping area is going to be about the same.

Basically, you need to compare the raw data to see the discrepancies that I'm referring to. When comparing volumes, you can use uncorrected data and get good readings because you're using the relative location data.

I'm using the Inspire 2 not the Phantom, but that isn't important. After my post I did corner one of the surveyors and he did enlighten me as to why they could not use our mapping for surveying, he did say he reviews the mappings and they are helpful to an extent, he didn't elaborate on what he gained or used the mappings for.
Thank you for your feedback.

 

[Jim Dow]

Regardless of what your client wants or what equipment you use (GPS/RTK/Cameras/Ground Control), you can improve your accuracy and product quality by using curved, non-traditional (non-linear/non-parallel) flight lines to mitigate the well-known systematic SfM doming (elevation) error produced as a result of the accumulation of lens calibration error when image blocks are processed using the SfM workflow - with images collected using traditional (linear/parallel) flight lines. Google "Gently Curved, Convergent, Non-traditional Drone Flight Paths". Justification for using curved flight lines is found in the following research:

Minimising systematic error surfaces in digital elevation models using oblique convergent imagery
Rene Wackrow

Jim H. Chandler
First published: 16 March 2011

https://doi.org/10.1111/j.1477-9730.2011.00623.x

Results of the simulation process, the laboratory test and the practical test are reported in this paper and demonstrate that an oblique convergent image configuration eradicates the systematic error surfaces which result from inaccurate lens distortion parameters. This approach is significant because by removing the need for an accurate lens model it effectively improves the accuracies of digital surface representations derived using consumer‐grade digital cameras. Carefully selected image configurations could therefore provide new opportunities for improving the quality of photogrammetrically acquired data.

I hope this helps. Compare traditional vs non-traditional flight lines shown in the attached files.

Jim Dow

 

[R Martin]

Not really... a Phantom uses the barometer for the altitude settings for a flight, so you'd have to compare the exif data between your flights/photos to see their approximate relation. The horizontal is going to be reasonably close, so I imagine that your mapping area is going to be about the same.

Basically, you need to compare the raw data to see the discrepancies that I'm referring to. When comparing volumes, you can use uncorrected data and get good readings because you're using the relative location data.

Your horizontal without control can be within 30 feet or so. The vertical is always questionable and needs to be truth-checked with other means and independently corrected if necessary. Our initial testing on the Inspire returned results without control with a roughly 5 foot shift to the southeast on all our test runs. With plywood control shot in in the field with a Geo 7X we closed the gap to within 2-5cm. With the addition of the Aeropoints, that improved even more horizontally. We always have problems with elevation data but we do the best we can based on numerous shots compared against benchmarks. You can always go back in to the EXIF file data and correct elevation based upon independent shots. And I am not a surveyor either but I do the best I can as a mapping tech/GIS analyst.