Topographic data is some of the most sought after information that can be generated by drones. To ultimately derive this data, terrain contours, point clouds, and digital surface models are created using software like Pix4D and Autodesk Civil 3D. Mark Blacklin is Data Integration and CAD Supervisor at CGRS, a Colorado-based construction, engineering, and compliance service company that serves the petroleum industry. Mark and Ian discuss the complexities of high precision drone missions, drone hardware and software, GPS systems used (RTK, check points), tips for setting ground control points, and what types of deliverables high-end clients expect.
You can follow Mark on Twitter at @MBlacklin.
Further analysis of this episode:
Mark Blacklin is Data Integration and CAD Supervisor at CGRS, a Colorado-based construction, engineering, and compliance service company that serves the petroleum industry. The company has been providing environmental compliance management for fuel system owners and operators for more than 25 years, and as you might imagine, drones have changed a number of things around how they approach such tasks. Mark has been involved in determining how those changes can and should be approached.
On episode #29 of the Commercial Drones FM podcast – How To Conduct High Precision Drone Surveys: What To Use and Tips On Improving with Mark Blacklin – host Ian Smith sat down with Mark to discuss specific details associated with some of things he does at CGRS, which range from logistics to client management. I was able to catch up with Ian to further detail a few topics from the episode including why a multi-rotor can be more beneficial than a fixed wing drone even when there’s a large amount of area to over, what kind of confusion can arise when discussing precision vs. accuracy and much more.
Jeremiah Karpowicz: You mentioned that when you were first starting the podcast you were looking to secure Mark as your very first guest. What made him the ideal person to kick off your show?
Ian Smith: Mark is an extremely knowledgeable professional and takes a pragmatic approach to his commercial drone operations. His extensive experience in CAD software, photogrammetry, and surveying has translated to drones seamlessly. He is an active drone industry community member and was someone that I’ve always respected. Any time I’ve had a question or needed an opinion on the way to conduct an operation, what equipment to use, software, processing techniques—whatever—he always had great and thoughtful feedback. The podcast is all about information; specifically, transferring information to the audience. This is what made Mark an ideal first guest for the podcast and I’m so glad to have finally had him on the show at the Commercial UAV Expo.
It was interesting to hear you two talk about why a multi-rotor can be a better fit for a project than a fixed wing drone, even if that means multiple take offs and landings. Will the true cost benefit of fixed-wing only be able to be achieved with BVLOS operations?
Good catch. First of all, we need to be honest with ourselves—people and businesses are routinely conducting BVLOS operations with their drones—fixed-wing and multirotor alike—whether we or the FAA like it or not. It’s shockingly easy to get a drone into a position where you cannot see it with your own two, unaided eyes. For those who do operate fixed-wing drones, I am willing to bet that whether by accident or by design, they get into BVLOS conditions fairly often and shrug it off. It’s something that’s tough to avoid. I’m not saying that people are flying many multiple kilometers away from their position on the ground, but by the true definition of the term, even if your aircraft is behind a building briefly, you’re operating BVLOS. With that out of the way, from experience, I know that fixed-wing drones can be a terrible pain to work with. You have to find a takeoff zone, a suitable landing zone, respect the wind, and have a lot more operational consideration than just taking off vertically with a rotary aircraft. In many cases you also have to transport and assemble a full ground control station and even a physical, catapult launcher. By virtue of that extra workload, the payoff of increased endurance does not typically pay dividends unless your operation is over extremely large areas. With increased data link distances, more flexible regulations, and even better endurance capabilities, I think small fixed-wing drones will finally come into their own and generate indisputable ROI within the next 12-36 months.
In what ways have you seen the terrain totally change or impact the scope and logistics of a project?
When conducting mapping missions in hilly or mountainous areas, terrain changes can alter the overall level of resolution in a data set. Ideally, a given data set has one static resolution value (i.e. 2 centimeters per pixel across the entire result). If the drone maintains a static altitude above sea level when operating over varying terrain and capturing imagery, the distance from the camera to the ground constantly changes. This creates inconsistent data because the ground (the subject) gets closer and further away from the static camera, causing varying changes in resolution. Alternatively, if the drone “hugs” the terrain and follows the contours of the ground at a constant altitude as it flies, the data’s resolution maintains consistency and thereby is much more desirable. This typically all comes down to the software you use. Professional drone pilots will opt for more robust software which allows options for terrain following/hugging or meticulously setting waypoints at the desired heights over the entire area of operations. Hilly terrain is also difficult due to variable wind and weather conditions and dictates where the takeoff/landing points are for maintaining visual line of sight and good quality radio link.
How often do you see people talking about accuracy when they should be talking about precision, or vice-versa?
This happens fairly often when people and businesses who are new to drone technology begin to experiment. The case that I see this come up often in is regarding photogrammetric volume calculations and deals with relative vs. absolute accuracy. Keep in mind that precision is independent of accuracy. Imagine you use photogrammetry to create a 3D model and point cloud of a large mound of dirt, about the size of a dump truck. You fly the drone around the pile of dirt, take a bunch of pictures from all angles, then upload those images into photogrammetric processing software and get your results—the 3D model and point cloud. Then, using more software you want to calculate the volume of this pile of dirt since it has been recreated in 3D. Due to the way that photogrammetry software reconstructs the dirt, it actually has excellent proportional reconstruction—meaning that the real-life volume of that dirt pile will be very similar (typically within 1-5%) to the 3D generated version of the pile. That means that there is great relative accuracy compared to the original. What if, from the same set of data, you want to know exactly where that same pile of dirt is located on the planet and get the GPS coordinates, within centimeters. That level of absolute accuracy is difficult to obtain due to common drone on-board GPS systems not being as accurate as other methods like ground control points. Resolution vs. accuracy is also something that comes up fairly often—but let’s save that for a later date.
ROI is a huge issue for operators of all sizes, but I thought it was a great point by Mark to mention that while they might not see a drone make something faster, cheaper or safer in everything it does, they can see those differences across a project. Do you think an issue that some operators run into is thinking or believing they’ll be able to see those sort of increases in efficiency with everything a drone does?
Totally. I say it at least once a week but really there’s a ton of hype around drones. Just by having one doesn’t pay for itself. When you utilize the drone in calculated, specific ways, you can achieve the ROI you’re looking for. Whether it’s intangible by increasing safety and eliminating the need for a human to get into a dangerous situation or tangible where you can literally attribute hours (and thereby dollars) saved by decreasing the amount of time it takes to conduct a wide area survey, the ROI you look for is related to your objective. This can also be why it’s sometimes difficult for a company to give you the exact numbers on what drone technology does for them. Looking at the big picture and comparing a drone to traditional methods is a great way to fully realize all of the benefits that drones provide. But in the end, a drone is not always the best tool for the job. A successful business already identifies with that and the drone becomes another tool in the toolbox for accomplishing the overarching goal—finishing a project within budget or increasing gains otherwise.
We went out flew it one morning for them, took us I think right around an hour to fly it captured all the imagery as well as the Toppo data, they had PLS set the benchmarks on the site about six or seven of them for us. And we you know had great results on that high accuracy quick turnaround of the data and the client was really really happy with with what we were able to provide and in the timeframe that we were able to provide it as well.[00:06:28] IAN: When you say toppo, so a lot of people say that and so some of the listeners might not know fully what the toppo means. So what exact when you say when you refer to something is a toppo like data set. What exactly is that? [00:06:40] MARK: So for our clients most of the time what they’re looking for is our contours, vector contours of the ground surface. Sometimes we’ll send off a point cloud of the data that’s getting – that’s not as common these days just because of the bulkiness of that dataset. It’s so many points on these projects that this software is are able to create nowadays we don’t typically send those unless it’s specifically requested. [00:07:13] Digital surface model digital terrain model is another format as well but most commonly we’re seeing that the clients want contour data you know in either the 6 inch or the one foot interval. [00:07:24] IAN: Ok cool. So contours are those kind of lines that yeah wIll be in intervals as the terrain rises there’ll be a line every six inches. And then if you look at that from a 2-D perspective you can kind of tell the lay of the land. [00:07:37] MARK: Exactly. [00:07:38] IAN: So what do what or why are the contours actually important, like what kind of usage is that? You know what value is that for the end user and client in these projects? [00:07:50] MARK: So the contours enable the client to compare it to existing. They probably went out ahead of the project with a conventional survey went in checked the ground conditions and now they can go back in and see from the contours are able to in civil computer aided design packages, build three dimensional surfaces of what the real world is. [00:08:16] So they’re able to replicate that if you will in a digital sense and then do all sorts of analysis on that. They can check where water is flowing. They can check the volume calculations on piles – you know elevation differences between where it was the ground originally was versus where they were either cut or filled into that area and just make sure that the grading plan is as they designed. [00:08:44] IAN: Yeah at my my full-time job over at DroneDeploy, yeah we’ve seen a lot of I guess demand for contour. [00:08:53] MARK: Yeah. [00:08:53] IAN: So those are very very important. You did mention I think you said that mission that we were talking about earlier was kind of on the side of a mountain or something like that steep terrain. [00:09:05] MARK: Yeah. [00:09:06] IAN: You’re in Colorado.So maybe what are some of the lessons learned. Actually I think this is interesting. First of all the UAV Expo I met about four people in the span of I don’t know a few hours and all of them are from Colorado. So I don’t know if it’s because the flights from Colorado to Vegas are cheap but there’s a lot of Colorado folks here and a lot of – there’s a lot of, maybe you have aspirations to operate a drone and you do live in hilly terrain or mountainous terrain. What are some lessons learned when operating a drone for mapping missions in that type of terrain. [00:09:39] MARK: Be careful first off because that that terrain will come up on you really fast before you know it. No it’s a tricky one and it really requires some forethought on the mission planning side of things as to how you’re going to handle the flight whether you’re going to take off from the low end of the project, the high end of the project if you’re going to stop the missions if you’re flying it just in one mission or multiple. There’s a lot of different parameters that come into play and what you need to be looking at in order to have a successful mission. [00:10:11] IAN: And ideally you want to have all of the images taken if you’re using this for photogram injury all the images taken at a uniform altitude above the ground or as the ground is undulating beneath the drone. The drone should ideally be following the terrain correctly and adjusting its altitude. [00:10:29] So sometimes that can be hard to accomplish if you don’t have the correct software that tells the drone what to do. [00:10:36] MARK: Just flIES flat a lot of the time. [00:10:38] IAN: And then you have alternating resolution on your final data. So that’s not desirable but I’m sure sometimes that happens. [00:10:47] MARK: Exactly. [00:10:48] IAN: OK cool. So what kind of hardware do you guys use at CGRS to accomplish these drone missions. [00:10:54] MARK: We’re currently flying the DJI inspire one pro with the larger camera on it and we’ve had really good results out of that platform for the types of needs that we have. [00:11:08] IAN: And the yeah it’s the X5 or X Factor. [00:11:11] MARK: Correct the X5. No, no it just shoots in RAW format. [00:11:15] IAN: That’s more for like video and stuff. [00:11:16] MARK: Exactly. Yeah, high bit rates. [00:11:18] IAN: Nice, So what else do you guys use? You guys use any type of like total station or like GPS stuff for ground control? [00:11:27] MARK: Yes, our ground control units we’re a trimble fan we use a unit a called GO7. It’s centimeter accuracy, so highly accurate. Not as good as a RTK unit perhaps but still high enough that it gets us the data that we need and the accuracy that we need on these projects and our clients have been really happy with it. So that GPS is definitely a requirement. As far as setting ground control on these projects. [00:11:59] IAN: And what could one expect to spend on such a GPS unit? [00:12:05] MARK: I think you know the prices are coming down every day but on a on a GO7 I think you’re looking in the neighborhood with the antenna and everything probably close to $20,000. [00:12:17] IAN: Ok cool not too cheap but if you want if you want to get accuracy then you’ve got to you have to pay the piper. So I do know that in some areas you can rent those on a daily basis correct. You know if you are starting to get into this. But actually I should advise if you’re going to start using ground control points and start calling this survey work you better be careful what you call your success in your business because there are actually laws state laws right. I don’t know prohibit you basically calling yourself a surveyor. [00:12:48] MARK: Surveyor. [00:12:48] IAN: Because you have to be a licensed surveyor to do that. [00:12:51] MARK: Right, yup. [00:12:51] IAN: So anyways. [00:12:52] MARK: It varies state by state. [00:12:53] IAN: Yeah. So be careful with how you represent yourself and just be cognizant of the fact that there are professional land surveyors out there that might not be taking too kindly to that. Okay great, and so what kind of, what kind of software. Well actually no. Let’s switch over, so you mentioned accuracy that you have to get this accuracy. Why is the accuracy important and when you say accuracy what do you mean. [00:13:18] MARK: So it’s important to note that there’s a difference between accuracy and precision accuracy is accurate to the real world as to what an elevation. And this is you know most important for us is the vertical control be the elevation component. We can already get really good accuracy in the horizontal and the x y with the imagery but the vertical the contour data the digital surface models that’s where really comes into play. It’s more difficult to get that accuracy. And so having a good survey unit having good ground control point lay out is critical to ensuring that that accuracy is there in the project. [00:14:05] Speaking of ground control flights we’re kind of taking this theme of accuracy and running with it now but I think I remember so you’ve learned quite a bit I think from your usage of drones and doing photogram atry from the air with with GCP. [00:14:19] Ground control points what how like I hear this question a lot it’s like how many ground control points do I need. And I think there’s a point of diminishing returns. You know if you set like 50 ground control points on an area you’ve just wasted a lot of time. You might as well do a conventional survey at that point. Yeah exactly. So what have you found is there like a sweet spot. I mean like for a given area how do you go about figuring out where I need to set ground. [00:14:47] We look at the lay of the land how much terrain is there. And as far as determining what ground control you need I liken it to a blanket flapping in the wind. The more points that you can help to tie that down within reason the closer you are going to replicate the ground underneath it. So if you can do four corners and that center point you’re probably in pretty good shape if you sprinkle a few more the middle of that blanket you’re going to be really really good. Now if you put like you’re saying 50 of them across that blanket you’re diminishing return. You don’t need that many but each project is different and there’s no no good way to say OK well on one hundred acres you need six ground control points. Every project is different. Accuracy needs vary. Projects vary and it’s it’s really impossible to say you know exactly how many you need on on any given project. [00:15:47] I’m really digging that metaphor. I’m like smiling and nodding profusely. On the other end of the mike over here that was really good. So I think that’ll help. [00:15:57] Some people might not even be actually familiar with ground control points so. Would you mind telling us like what’s the process of setting ground control. We did talk about that GPS unit very aggressive GPS GPS unit. Maybe I’ll just let you take that and run with it like sure if you’re if you’re explaining to someone who’s very new how would you kind of tell them about ground control points. [00:16:18] So ground control is a method of tying the photograph metric image processing to the real world known coordinates. So in the typical workflow what we would see happen is you go out before you even fly any any area you go out and you choose the ground control point locations you lay an aerial target something that’s visible in the drone or the UAV imagery when you’re flying preferably a high contrast target of one form or another. Again before you fly or go out and you’ll survey those points so that you know exactly where are they where they lie. [00:16:58] Then you can go ahead flights and make sure that GPS you are correct. So you drop the point on the ground and then you come with that stick out the really expensive stick with this little disc on the top that you have to be really accurate GPS. So the reason why you use that stick of course as well is because it’s so much more accurate than the GPS that’s on those drones correct. OK cool and you see get the stick and then you stick it on the ground control target and then you record the GPS GPS data onto the SD card exactly X Y Z location where that target is in the real world. [00:17:31] And then when you go to process the data after the you know it after you’ve flown the mission you can go ahead and assign those ground control points to known places so you pick out an image and say OK I can see that that target in this image and I know that this image is at this exact location in the real world and that is essentially that pan on the blanket if you will and helps tie the digital model down to the real world coordinates with high accuracy like you’re saying it’s not as good. The GPS on board the UAV is not as good as what that survey grade unit can can get and can obtain for us through that. [00:18:11] So are you excited to eventually use and I know that these are pretty expensive now but some drones do you have Artie cage onboard which in some cases can not necessarily negate the need for ground control points but actually make it so. If your accuracy tolerances are a little bit more loose loose or others like I mean you can get five centimeters of accuracy. Are you guys planning on maybe using any AR T.K. equipped drone systems in the future. [00:18:42] Our workflow at the current time says that we we use ground control points known surveyed ground locations because what we do is we’ll include checkpoints on all of our projects as well which are points that are surveyed but not used in image processing. So they are T.K. on board can help speed up the image processing because it knows precisely where each picture was taken. But as far as the data we always want to ground truth as it were where the data is on the ground make sure that we have known locations and verify that against the process data. So the T.K. on board I think it’s a powerful tool. And like you say used in the right circumstance it’s going to be helpful. It’s going to be beneficial. But for us and our workflows we always want that ground truth happening. [00:19:36] Sue about software then. So we talked about hardware now and it was really just awesome explanations across the board. [00:19:43] What kind of software do you guys use to accomplish your missions. I mean maybe from like a to z like starting the mission. I mean what is the software suite kind of resemble CGI us. [00:19:55] Do we want to get into specifics here or just I guess like whatever you want to talk about like OK we kind of use this for flight planning sometimes or we use this for processing and then like maybe what you finally do with you know once you get the data and you have to like post-process that or if you don’t like that yeah so typically our flight planning app that we’re using with the inspirers drone deploy we’ve found them to be the definitely the most robust and most reliable flight planning app out there. We’ve tried a lot of the other ones and just can’t get the stability that we get with drone deploy. [00:20:33] That did not plan this by the way. [00:20:35] You know this isn’t a shameless plug for drone boy. It’s just the way the way our work flow is what you actually use. Right. Right. Next up for for image processing we actually use picks 40 in a house. And that’s really just for ease of including ground control points at this point. We’ve used drones deploy online and had good results there but we don’t have the control with ground control it’s a little little trickier to have that data included it’s not that it’s impossible it’s just a little little more leg work if you will. [00:21:08] Yeah and you guys really need as much flexibility and control as possible exactly for your operation. It’s just the way expense to speak to you of course. [00:21:17] Once we have the the data outputs from 640 40 which most commonly Like I said earlier is the the aerial imagery and the contour data we bring that into a package called Autodesk civil 3D which is a computer aided design program and do our final work and grading plans and Watershed analysis all that kind of stuff. Your domain. Yes. And that’s my world. That’s civil civil design that’s where I’m I’m happiest. Been doing that now for almost 15 years. [00:21:47] Do you have like a super crazy workstation computer that you use. [00:21:52] Yeah we’ve I’ve got pretty high end laptop that I actually do most of my work on a Dell DELL laptop that’s. Well last year it was one of the biggest baddest ones they made. And then our processing computer is pretty robust as well. All liquid cool and fancy that way. So nice set up for sure. [00:22:11] Very nice. Cool. Great. So let’s see we’ve talked. [00:22:16] We have we’ve covered a lot of these topics here so maybe we can talk about specific or as specific as we can get our own eyes. So the return on the investment that you guys have seen I mean there’s about I mean there’s three general ways that I kind of think about it like OK time saved money saved and then increased safety. Right. [00:22:38] Have you experienced any of those three while using drones on the job we’ve seen in some form or another we’ve seen all three of them maybe not simultaneously all on one project but to some degree we’ve seen them all. We’ve seen the cost savings definitely as far as speed that we can gather data on on a site. We’ve seen the safety when doing volumetrics on large piles where we’re not sending somebody scampering up the side of a loose pile doing volumetric analysis and trying to survey a pile where we’re really seeing it seeing it all in one form or another. [00:23:20] Do you guys see how old is C-G. [00:23:22] The company we are 29 years this year we started in 1987. [00:23:28] Are you guys a startup. It’s funny because like when do you stop being a startup. I don’t know anyway. So do you see the point of that was DC or drone usage rising as time moves on. [00:23:41] Definitely our drone use is in its infancy right now as I think it is across the board not just for us but the entire industry obviously is is in its infancy and growing every day. I can definitely see the day when drones become a nother tool in the toolbox where they are basically checked out or you know used. Okay I’ve got a project coming up next week and we’ve got all sorts of different equipment at our company that we check in check out. And the drone is going to be another tool in the toolbox. You know much like a shovel is these days you’re going to sign out a drone and take that to the field and do your work with it. [00:24:21] Nice. And what’s the. To you what’s the most exciting thing happening right now in the drone industry. I mean we’re past part 1 0 7. I think when we initially recorded that first I was just counting never aired. Yeah we talked about oh I’m excited for tomorrow seven and everything ok now. OK whatever who cares. Part one of seven they did a great job. So looking forward I mean what’s the most exciting thing happening right now. [00:24:46] The drone industry to you gosh there’s so many different facets right now that are moving forward at lightning speed. It seems like you know sensor size is a big one. I’m seeing these LIDAR pucks coming down in size getting getting more to the point where you don’t need a big ass 1000 to haul things around. That’s going to be an interesting progress to see that happening. And that is used LIDAR currently or. No we don’t but we’ve definitely had requests for it. And typically what’s happening is our clients request it and then they say no thanks when they hear the price. You know the cost cost benefit just isn’t there yet. But as these sensor sizes shrink typically the cost is coming down with that. So it becomes more and more realistic to try and start using those in a way the platform. [00:25:44] And so those the the the appeal of LIDAR is because it’s like ridiculously accurate right. Right on. [00:25:51] Yeah. And you get multiple returns on the on the data whereas with photogram tree you only get the first returns you only get the top of a building or the or the top of a tree with LIDAR you can get first and last return which is the bottom. The ground underneath the tree as well which is really helpful when it comes to doing digital terrain models or digital surface models. [00:26:14] So it penetrates like the fingers actually. OK. That’s really cool. Nice. That sounds cool. You’re going to say something else I think before I cut you off about LIDAR I wanted to touch on that before I forgot. Oh gosh. [00:26:28] I’m not sure I’m not excited about anything else except a light. Well what are you. So you’re attending the show as a I guess an end user of right. OK. [00:26:39] Yeah we’re we’re in rest see the sessions and really learn how other people are applying them. You know we know in our own little world what’s happening and how we do things we talk with the customers who are wanting to get going and wanting to fly their own. But this is really an industry that we want to check out how other people are doing things. What are we missing or what can we share with our process and learn from each other here. [00:27:05] Awesome. That’s awesome. Cool. Well it looks like it’s going to be a great UAD Expo. So Mark thank you. [00:27:12] Thank you so much for joining me here. I’m so glad we got to do this in person. We’re finally going to get to air conversation. This is one of the ones I was just so excited for because if I ever have any questions or need to pick someone’s brain that’s an expert on surveying and using CAD software and stuff like that my first person I turned to is Mark. So really appreciate you being here. It’s been a great great chat. [00:27:36] I think a lot of people are going to learn some stuff on this and you can go ahead and as a listener you can go ahead and check out CGRS.com/UAV and you can kind of see the web page that CGRS has set up for their clients to see how they operate and what kind of stuff that they do and offer. And you can follow Mark on Twitter at msblackline. That’s Mike Sierra. B A C K L I N. And of course while you’re at it you can go ahead and follow the podcast. [00:28:08] MARK: Definitely. [00:28:09] IAN SMITH: @dronespodcast on Twitter and Facebook.com/dronepodcast. Go ahead and leave a review or a comment or send us an e-mail, tweet us find out. Maybe some more questions that we can get answered by Mark. So Mark thank you once again. [00:28:24] MARK BLACKLIN: Thank you Ian, thanks. [00:28:25] IAN SMITH: All right. Fly safe everyone. Cheers.
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