When UAV\drone data is collected and post processed properly it can generate highly accurate elevation data that can often rival LiDAR. The problem is that many providers of drone data actually do not have the knowledge or skill in either data collection or post processing to create a survey grade digital elevation model or other photogrammetric products.

Over the last five years J.R. Canadian Mapping has been confronted with what some perceive as our competition. It seems that every other month someone purchases a DJI Phantom and is starting up a UAV company within our service region offering surveying or mapping services. These pop-ups are offering their services at a meager cost and claim to be offering the same products as my company. I am constantly defending my company's services and costs against pop-ups which potential customers perceive as our competition. I perceive these pop-ups as nothing more than a nuisance muddying the industry and confusing potential customers of quality photogrammetric data. Owning a drone does not make anyone a surveyor or photogrammetrist and it does not give one the ability to produce survey grade products.

Let us be clear on one thing; a drone does not do any mapping! A drone is a tool that collects data, usually photography or LiDAR, during a pre-programmed flight; nothing else. If the operator is unfamiliar with the requirements for data collection for a project the collected data may not even be useful. The data must be collected at the proper elevation with the proper overlaps at the correct time of day to get optimal data required for post processing. Data collection is the simplest process in photogrammetry but because someone owns an off the shelf quad-copter does not mean that they have any knowledge or skill in collecting data let alone processing it.

A drone is a tool like any other. Owning a hammer does not make someone a carpenter, owning a stethoscope does not make someone a doctor. Owning a drone does not make someone a surveyor or photogrammetrist and does not mean they know how to collect or process aerial data.

Once data is collected it must be post processed. Mapping products are only derived from the post processing of the aerial data. Having the understanding and the tools for post processing is the key difference between a professional surveying and mapping company and these pop-ups.

All pop-ups, known to me, use either automated software or hire external companies to process their data. Most of these pop-ups usually have no way of checking the integrity of their data nor do they even know how to check their data. I have seen data collected and post processed by these pop-ups and their data providers over the years and to date I have only seen some photography, a few orthophotos (most automated orthos are quite bad with raggedy edges around buildings and gross distortions all through vegetation and structures), and some digital surface models that were acceptable. 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.

In defense of these pop-ups they are buying into the marketing by drone manufacturers and photogrammetric software developers offering push button solutions for surveying requirements. Of course drone manufacturers and software developers are promoting their products as a push button solution; it is in their best interest to increase their bottom line. I believe advertising by these providers in this manner is blatantly false with the advertising aimed at non-professionals to sell their products and make a profit. Anyone with surveying or photogrammetry expertise knows that these claims are false. We have drones in use in our office as well as several of the close range photogrammetric software solutions but we knew when we purchased them that they were not push button solutions no matter what was advertised.

I have personally never used nor seen an automated photogrammetric software or process that will produce a survey grade bare earth digital elevation model in most scenes. The only times I have seen an accurate automated DEM is when the ground is already bare earth or very close to bare earth. However if the bare earth is monotonous in color and texture the software will fail. A fresh earth pile, a worked quarry, or an open pit mine would be some good examples of a bare earth surface. With a few weeks of study and training most people working within these areas could go out, buy a cheap drone, and the cheapest processing software and get excellent results. Even with a few buildings and other minor obstructions I have seen accurate results in the above described areas using the simplest of tools and software.

If there are many obstructions on the ground (vehicles, buildings, brush, trees, grass) automated processes fail miserably. In my company we have tested and performed trials with most major close range photogrammetric software packages and to date none of them can create an accurate DEM in an automated process in non-bare earth scenes. JRCanMap has tested Pix4D, Menci, AgiSoft PhotoScan, AeroHawk, PieNeering, and Sure; just to mention a few. The company SimActive which offers the software Correlator3D at a cost of almost $50,000 produced such horrific products in our trials it is hard to believe that they are still in business. I have not seen any of the companies offering processing services create a good bare earth DEM from these scenes as I suspect they are also using automated processes. Any software company that wishes to dispute this claim is welcome to contact me and we can set up a trial on an open platform available to anyone qualified to evaluate the software. If we find the data accurate we will post your accuracies, retract this statement, offer an apology, and praise your software. Honestly, I am not too worried that any company will accept my challenge as the software vendors all know the shortcomings of their software.

The post processing reports generated by these automated software often claim to have accuracies within a couple of centimeters. I am uncertain exactly how these numbers are generated, where they come from, or what they are supposed to mean. When I take some automated surfaces (both DSM and DEM), with cm level accuracies in the post processing report, and view them on a stereo photogrammetric workstation with a network of RTK surveyed check points the data can be in error by several meters depending on the ground. Thick grass, shrubs, trees, and monotonous textures and colors are the greatest obstacle to automated processes producing accurate results. The only place where accuracy is usually guaranteed is around the ground control points which should be placed in open easily viewed areas. Adding to the problem, pop-ups often do not even collect ground control points. Move away from the ground control points and quite often the surface begins to wobble or wave. An easy check for this is to find a very large puddle or a small pond which is a natural level and see if the shoreline is the same elevation around the entire water body. To date I have never seen a level shoreline around a water body in any automated surface.

I have been creating 3D models and processing aerial photography for almost 25 years; long before it was a fad with drones. I possess a B.Sc in Physical geography specializing in remote sensing as well as a technical diploma in surveying and photogrammetry. I have personally completed hundreds, perhaps over a thousand, photogrammetric projects over the years ranging in size from a few hectares to hundreds of thousands of hectares. I began my photogrammetric career operating an analogue Wild B8 and saw the advancement of digital systems from their inception. During my career I have used most full scale and close range digital photogrammetric software. Needless to say I am no newbie. Only in the most perfect situations have I seen any software create a survey grade DEM from total automation. In most cases a skilled photogrammetrist must take an automated DEM into a stereo environment on a photogrammetric workstation and manually edit the data to create a surface that meets survey standards. The hardware and software to complete such a task can easily run over $100,000. The education and experience needed to complete an aerial survey properly and the cost of the software and equipment to post process and check the data justifies the higher costs of quality products. If you are a pop-up and you are not doing the above procedures then your data is not survey grade and should not be sold as such. If you are offering pretty pictures then that is what you should be advertising.

Software companies making false claims and pop-ups offering poor products are destroying the reputation and validity of the fledgling drone industry before it really gets off the ground (pun intended, I just could not help myself). To the software and hardware companies offering push button survey solutions, add some disclaimers to your marketing pointing out the limitations of your software and equipment. To all the pop-ups out there, please stop offering services for which you do not even know the proper names. Spend a few years to educate yourselves in surveying and photogrammetry before running around making claims that you do not know how to accomplish nor support.

To all of the potential customers out there looking to use drones and their products...Caveat Emptor.



