TLG Dan Inloes

Land Surveyor License Needed (Nuts and Bolts)

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Is This Legal?

This thread is intended to develop and discuss key points on whats needed to provide data to surveyors and engineers. The Nuts and Bolts of the question "Land surveyor license needed?" 

I've been involved in the thread "Licensed Surveyor License Needed" and my personal intro thread that discussed integrating drones into my day to day duties as a Survey Tech. I use an Inspire 1 Pro with an X3 camera with an Ipad Pro and have employed it on over 60 projects from 1 acre plots to a 21 mile by 2000' corridor project over the past year with great success. On my intro thread, I stated that if anyone had any questions regarding drones and surveying, to drop me a line or call me and I'd share any and all info I've accumulated over the past several years of experience as a drone pilot in the survey industry. That still stands and I am eager to help where I can. It turns out that a lot of you are interested in generating survey/engineering deliverable/products and have questions about all aspects of the process. Lately, I've received questions from several guys asking the same questions and I want to take the time to clear the air and give some input on the most common and most important questions I've fielded over the past year. Its also worth noting that everyone thats contacted me regarding this topic was not a licensed surveyor or a licensed photogrammetrist. Just regular guys trying to figure this out. Also worth noting, I am not a lawyer and my thoughts and opinions stated hereon are intended to be for reference only and is not intended to be legal advice. I'm wading through the same struggles that you are, I'm just a few years ahead of most and have a lot of insider experience. I tell the guys that call me, "if you want to live on the bleeding edge of technology, your going to bleed". I am no exception to that saying and hope this thread can be your proverbial band-aid to some of your issues.

In order to accomplish this task (producing products for surveyors and engineers) and maintain clients and grow your business, you must have a great understanding of state law, FAA Regulations and Authorizations, UAS Piloting, Weather Conditions, AutoCad, Photogrammetric Methods, and the most fun, Geodesy and Map Projections. Sure you can buy a Phantom, take some pictures, upload them to a cloud based processing firm, and deliver that, but I'm here to tell you that you're going to fall short and your data will be unreliable and not reproducible, which is a deal breaker for surveyors. Cloud based processing firms can serve as a useful tool for some products, but the products that pays the bills will come from in-house processing. Personally, I use a fire breathing processing machine and Pix4d to produce 100% of my deliverable. 

I'm just going to jump right in with the most important question you need to ask yourself.

Q: Is it legal to produce data for surveyors and engineers? 

A: This is a loaded question that does not have one answer. It depends on which state you intend on working. You need to research your states statutes and determine if there is a Photogrammetry license in your state. I live in Idaho and there is no such license. But, there is a Photogrammetry license in Oregon. This means that in Oregon, if you're caught producing "photogrammetric data that is intended to be used for measurements" (orthos, ortho-planes, contours, volumes, etc.), you can get sued for providing a professional service without being licensed. If you get sued, your drone insurance is not going to cover it. You need professional liability insurance, which is not available unless you are licensed by the state. So, first look up your state laws on photogrammetry and if you find nothing, look up the laws for surveying. In Idaho, the word "photo" is only mentioned a few times in the state code for surveying. A couple times for photo ID and once for photogrammetry. The one mention of photogrammetry basically says that surveyors can employing a variety of methods to generate measurements, one of which being photogrammetry.  That's it. This means that there are no state laws that prohibits or restricts what Billy Bob's Drone Services can provide, or to whom he can provide them to.  Oregon on the other hand is very different. This varies greatly from state to state, so do your due diligence. 

In the more strict states, the key phrasing that you need to be looking for is "responsible charge".

The best way of explaining this is to run a scenario.

The field guys that work for a PLS are "under the responsible charge" of the PLS because they are employees of the PLS. If you're providing a service or product that measurements are intended to be generated from as an independent contractor, your business, by nature, is not directly overseen by the responsible charge of a PLS, unless you have one on staff. In which case, you'd be providing a stamped product. But 99% of you are not licensed nor have a PLS on staff. That's why we're talking about this. 

If you find yourself trying to conduct business in a state where photogrammetry is blanketed by the survey license or a photogrammetry license, you've found yourself between a legal rock and a hard place. I am in a unique positions as I work for a PLS and am eligible to become licensed, as of last April. But for the vast majority of you, you are not a PLS and have no intent on becoming such. 

You might be saying, "well if I'm generating survey grade data, I'm going to be working very closely with the surveyor and he's going to be deeply involved in what I'm doing". That doesn't cut it in terms of the law. Its my understanding that by virtue of the fact that you are conducting business as an independent contractor, you are not under the responsible charge of the clients PLS. The only way I can see this working is if you become a temporary employee of the PLS. In essence, the PLS would be hiring you as a specialist field crew member that has all the authorizations and FAA requirements dealt with and has his own equipment to collect data for a specific project. Once the product has been developed, the terms of your employment would end. 

So...

First things first. Is it legal to do what you want to do in your state? This is the most important question you can ask yourself before you develop a business plan for your drone business. 

I look forward to continuing this thread with anyone thats interested in voicing their opinions and questions. Its my goal for this thread to cover specific questions as it pertains to this profession. As more questions arise, I intend on heading each question topic with a big, bold header like I've done on this on. (Is This Legal)

As always, I'm available and willing to talk to any and all regarding drones and surveying. Feel free to drop me a line. And above all, Safe Flying!

Best regards,

Dan Inloes

Dan@allproaerial.com

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Hi Dan,

Thanks for jumping in.

First question.

When Google provides orthoimagery in a state that prohibits photogrammetry without a license, how come they don't get sued or at the least a cease and desist?

Edited by Dave Pitman

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I searched the Revised Code of Washington (RCW) and could not find reference to a license requirement for photogrammetry.  This is the law regarding surveyors.

Relevant snippets below with the source here:

  http://app.leg.wa.gov/RCW/default.aspx?cite=18.43&full=true

Quote

18.43.010
General provisions.

In order to safeguard life, health, and property, and to promote the public welfare, any person in either public or private capacity practicing or offering to practice engineering or land surveying, shall hereafter be required to submit evidence that he or she is qualified so to practice and shall be registered as hereinafter provided; and it shall be unlawful for any person to practice or to offer to practice in this state, engineering or land surveying, as defined in the provisions of this chapter, or to use in connection with his or her name or otherwise assume, use, or advertise any title or description tending to convey the impression that he or she is a professional engineer or a land surveyor, unless such a person has been duly registered under the provisions of this chapter.
 
(6) "Land surveyor" means a professional land surveyor.
(7) "Professional land surveyor" means a person who, by reason of his or her special knowledge of the mathematical and physical sciences and principles and practices of land surveying, which is acquired by professional education and practical experience, is qualified to practice land surveying and as attested to by his or her legal registration as a professional land surveyor.
(8) "Land-surveyor-in-training" means a candidate who: (a) Has satisfied the experience requirements in RCW 18.43.040 for registration; (b) successfully passes the examination in the fundamental land surveying subjects; and (c) is enrolled by the board as a land-surveyor-in-training.
(9) "Practice of land surveying" means assuming responsible charge of the surveying of land for the establishment of corners, lines, boundaries, and monuments, the laying out and subdivision of land, the defining and locating of corners, lines, boundaries, and monuments of land after they have been established, the survey of land areas for the purpose of determining the topography thereof, the making of topographical delineations and the preparing of maps and accurate records thereof, when the proper performance of such services requires technical knowledge and skill.

With the above being the law.  What is your opinion about providing stockpile volume estimates that contain the disclaimer:

The provider of this estimate is not a licensed surveyor, and these volume estimates are not represented to be at any level of accuracy and should be used at ones own risk.

Edited by Dave Pitman

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On 1/19/2018 at 8:05 PM, Dave Pitman said:

I searched the Revised Code of Washington (RCW) and could not find reference to a license requirement for photogrammetry.  This is the law regarding surveyors.

Relevant snippets below with the source here:

  http://app.leg.wa.gov/RCW/default.aspx?cite=18.43&full=true

With the above being the law.  What is your opinion about providing stockpile volume estimates that contain the disclaimer:

The provider of this estimate is not a licensed surveyor, and these volume estimates are not represented to be at any level of accuracy and should be used at ones own risk.

Just as reference, here is Oregons ORS 672.002

(1)"Board" means the State Board of Examiners for Engineering and Land Surveying.

(2)"Engineer," "professional engineer" or "registered professional engineer" means an individual who is registered in this state and holds a valid certificate to practice engineering in this state as provided under ORS 672.002 (Definitions for ORS 672.002 to 672.325) to 672.325 (Civil penalties).

(3)"Engineering intern" means an individual enrolled by the board as having passed an examination in the fundamental engineering subjects.

(4)"Geodetic survey" means a determination of the size and shape of the earth or the position of any point on the earth.

(5)"Land surveyor," "professional land surveyor" or "registered professional land surveyor" means an individual who is registered in this state and holds a valid certificate to practice surveying in this state as provided by ORS 672.002 (Definitions for ORS 672.002 to 672.325) to 672.325 (Civil penalties).

(6)"Land surveying intern" means an individual enrolled by the board as having passed an examination in the fundamental land surveying subjects.

(7)"Photogrammetric mapping" means an evaluating and measuring of land that is limited to the determination of the topography, area, contours and location of planimetric features, by using photogrammetric methods or similar remote sensing technology, including but not limited to using existing ground control points incidental to the photogrammetric or remote sensing mapping process.

(8)"Photogrammetrist" means an individual registered with the board and holding a valid certificate to practice photogrammetric mapping.

(9)"Responsible charge" means to have supervision and control of:

(a)The engineering design of works with responsibility for design decisions;

(b)Land surveying work for the purpose of ensuring conformance to the relevant requirements of law and sound surveying practice; or

(c)Photogrammetric mapping project work, which may include, but need not be limited to, work regarding the extent of coverage, location of ground control, aerial photography or similarly remotely sensed data, the measurement of features detected by remote sensing equipment, quality control for compliance with standards and specifications and the presentation of findings.

(10)"Supervision and control" means establishing the nature of, directing and guiding the preparation of, and approving the work product and accepting responsibility that the work product is in conformance with standards of professional practice. [1971 c.751 §1; 1983 c.614 §1; 1995 c.33 §1; 1997 c.210 §1; 2005 c.22 §475; 2005 c.445 §6; 2009 c.259 §1; 2015 c.576 §9]

Further more.

(1)A person may not practice photogrammetric mapping in this state unless the person is registered and has a valid certificate to practice land surveying, engineering or photogrammetric mapping issued under ORS 672.002 (Definitions for ORS 672.002 to 672.325) to 672.325 (Civil penalties).

(2)A photogrammetrist shall, upon registration, obtain a seal of the design authorized by the State Board of Examiners for Engineering and Land Surveying. The registrant shall sign and stamp with the seal of the registrant each final document, including drawings, specifications, designs, reports, narratives and maps issued by the registrant. The signature and stamp of a registrant constitute a certification that the document was prepared by the registrant or under the registrant’s supervision and control.

(3)A photogrammetrist may perform services defined as photogrammetric mapping under ORS 672.002 (Definitions for ORS 672.002 to 672.325). A photogrammetrist may not engage or offer to engage in an act constituting the practice of land surveying other than photogrammetric mapping. [2005 c.445 §2; 2009 c.259 §3]

and last but not least.

In addition to any other penalty provided by law, any person who violates any provision of ORS 672.002 (Definitions for ORS 672.002 to 672.325) to 672.325 (Civil penalties) or any rule adopted thereunder shall forfeit and pay to the State Board of Examiners for Engineering and Land Surveying a civil penalty in an amount determined by the board of not more than $1,000 for each offense.

So, as you can see, states rules and regulations regarding photogrammety can vary considerably. I looked up the rules in Washington and as you found, there is no mention of photogrammety. Like not even once. 

As to answer your question. 

On 1/19/2018 at 8:05 PM, Dave Pitman said:

What is your opinion about providing stockpile volume estimates that contain the disclaimer:

The provider of this estimate is not a licensed surveyor, and these volume estimates are not represented to be at any level of accuracy and should be used at ones own risk.

I'd say if you are providing volumetric data in Washington, theres nothing in the Washington code that says you cant. If you want to put a disclaimer on your data, you can totally do that, if not to just cover your bases in terms of liability, but to clarify what the accuracy actually is. I plan on going over this in my next post. 

Great question. 

 

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On 1/19/2018 at 7:27 PM, Dave Pitman said:

Hi Dan,

Thanks for jumping in.

First question.

When Google provides orthoimagery in a state that prohibits photogrammetry without a license, how come they don't get sued or at the least a cease and desist?

My first thought is that the imagery thats available by google is not orthoimagery. Its a compilation of stitched satellite imagery. If you look carfully at the google imagery, you can almost always see the sides of trees, buildings, light poles, etc. If overlay google imagery underneath survey linework, you can see that there is significant distortion (significant in survey land) in the imagery. With out diving into a big search on this topic, I'd say that google has an army of attorneys and I'm sure theres language somewhere that says that they release all liability as to how their imagery is used. 

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11 minutes ago, TLG Dan Inloes said:

My first thought is that the imagery thats available by google is not orthoimagery. Its a compilation of stitched satellite imagery. If you look carfully at the google imagery, you can almost always see the sides of trees, buildings, light poles, etc. If overlay google imagery underneath survey linework, you can see that there is significant distortion (significant in survey land) in the imagery. With out diving into a big search on this topic, I'd say that google has an army of attorneys and I'm sure theres language somewhere that says that they release all liability as to how their imagery is used. 

I agree.  But disclaimers do not make any difference if someone needs a lic according to state law, correct? 

I'm guessing it has more to do with the army of attorneys that is the deterrent to state associations raising a stink.  The sole proprietor uas operator on the other hand is easy pickings. 

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26 minutes ago, TLG Dan Inloes said:

I looked up the rules in Washington and as you found, there is no mention of photogrammety. Like not even once. 

As to answer your question. 

I'd say if you are providing volumetric data in Washington, theres nothing in the Washington code that says you cant. If you want to put a disclaimer on your data, you can totally do that, if not to just cover your bases in terms of liability, but to clarify what the accuracy actually is. I plan on going over this in my next post. 

Great question. 

 

Thanks for having a look at Washington's RWC.

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RTK/PPK GPS Equipped Drones

Another questions that I'm asked almost every time I'm contacted by guys looking for guidance is about strapping a PPK GPS system or a RTK GPS system on to their drone. This topic usually arises after we discuss how to create survey grade data and what it really takes to pass the QC of a surveyor.

Basic principle: Unless you have a survey grade GPS system ($$,$$$.$$), can set your own ground control points (GCP's), and understand how to process GPS data and assign a coordinate system to your points (horizontally and vertically), you will need the assistance of a surveyor in order to create survey grade ground data from drone photography. Bottom line. GCP are required to create survey grade ground data. 

Survey Grade: The combination of the internal relative accuracy of your data (the distance between two points) and the geospatial accuracy (are the coordinates of those two points accurate and tied to a known coordinate system). 

GPS 101 - All GPS is created equal. All GPS systems collect and log positions in Lat/Long and ellipsiod height, also know as grid heights. Sometimes its referred to as HAE, Height Above the Ellipse.  And just FYI, the ellipse is a mathematical representation of the earths gravity as a given location. Most commonly the coordinate system GPS units collect data in is WGS84, World Geographic Coordinate System as defined in 1984.

RTK/PPK vs. Non-RTK/PPK: RTK (real-time kinematic) and PPK (post-processed kinematic) enabled drones use the same GPS as the GPS that comes stock in your drone except the GPS on the drone is receiving correction data from a base station that you set up on site. The base station is collecting GPS readings as you're flying, getting more and more accurate as the reading are collected and averaged, and sends correction data to the drone, adjusting in real time the GPS readings of the drone. These reading are then used to tag the location of the drone on to each image. These corrected positions are stored in the form of EXIF data on the images. One reading/location per image. 

Depending on the software your using, the EXIF data on each photo can then be converted to state plane coordinates during post-processing by means of the correction data from the base station. The EXIF data is used during the first process of your data processing. The photogrammetry software uses the EXIF locations to orient the images in the pattern you flew so that it knows which photos to compare against to create tie points between all the photos to tie them all together. It also uses the elevation of the photo to calculate the vertical component of ground coordinates. 

This then leaves you with images that have fairly accurate WGS84 coordinates or a fairly accurate state plane coordinates, but the positions represent the location of the drone, not the ground. True ground coordinates are calculated and generated during the processing of the images by means of triangulation between a collection of photos and by using the EXIF data of the image as a reference point. Utilizing PPK or RTK on your drone can produce better results than if you were to not use GCP's at all, but it can also incorporate errors into your project because your relying on the correction data from one point on the site, as apposed to using several GCP's that are strategically place around your site. The error will grow the further away from the base station you get, guaranteed. 

If your software does not allow you to convert the image locations to state plane, your stuck with WGS84 coordinates. By virtue of the fact that raw GPS locations are WGS84 coordinates with grid heights and that the surveyor will most likely want the data in some other coordinate system, likely State Plane Coordinates with ground heights, there is a significant distortion factor between the two coordinate systems that needs to be accounted for. The distortion that I speak of can be imagined as a move, scale, rotate, with a vertical offset and a touch of stretching.

In order to adjust for all these factors, you have two options. You will either need GCP's in the desired horizontal and vertical coordinate system or a combined scale factor with a geoid separation (which are generated when post processing survey grade GPS data). This distortion is accounted for by using one of these two methods when processing your data, not by use of a more precise location of the drone. So, in short, solely utilizing a drone that's equipped with PPK or RTK will get your raw data closer to actual WGS84 coordinates or state plane coordinates, but will not be accurate enough to be accepted by a surveyor.

You might ask, well cant the surveyor adjust the data after the fact to get the data onto state plane? No. This correction must be accounted for during the processing of the imagery by using GCS's. Using GPS's is the more effective and hands down the best way to generate accurate and reproducible drone data.  

The one advantage of utilizing RTK or PPK enabled drones is that it greatly stabilizes the drone during fight, horizontally and vertically. More importantly, vertically. If there's significant vertical relief on your site and you have the ability to maintain a constant height above the ground as you're flying, this can help maintain the Ground Sample Distance (GSD) of the photos. GSD is the size each pixel represents on the ground in each photo. Maintaining a constant GSD is important when striving to create the most accurate ground data from images. 

So... PPK or RTK on a drone. Does this make your data Survey Grade accurate? No. Does it make your data more accurate? Yes.

A quick recap of WGS84 and State Plane. WGS84 covers the entire world. Its goal in life is to flatten out a round earth and allow us to represent geographic locations with a number. Sanity check: lines of latitude are constant, lines of longitude converge at the poles. Therefor, if you take a square that's 10 degrees of latitude by 10 degrees of longitude, depending on where you are in the world, the north line and the south line are going to be different lengths. It'll look like a square with the top or bottom corners smashed together slightly. State Plane Coordinates are not like this. There is an x axis and a y axis, both constant. State Plane Coordinate Projections are broken down by state. Some times a state will have several state plane zones. Like state plane west zone, state plane central zone, and state plane east zone. These projections are much smaller than the WGS84 projection as to restrict on the effect of convergence. If you are to understand the reason why PPK enables drones does not directly relate survey grade ground positions, you must first understand this basic concept.  

Final Thoughts. I can tell you that I'm not just regurgitating info that I've researched. I've flown a site with a drone that had PPK GPS and utilized a base station. I've flown the same site with the same drone with the same light conditions with out the PPK GPS while utilizing well placed, highly accuracy GCP's. In survey lalaland, there no comparison. They were close, but distortion grew the further away you got from the base station when relying on the PPK system solely. In the extreme, the worst variance I found was over 2 feet at the furthest point away from the base station, about a quarter mile away. 

Thats my 2 cents on the topic. This is a hairy topic and I encourage your input. 

More to come, and as always, fly safe!

Dan Inloes

Dan@allproaerial.com

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This is a great topic of discussion.  I appreciate that most surveyors are engineers and have followed a path of education and professional licensing to get there.  But does the greens/turf manager for golf course need survey grade data to compute his fertilizer requirements?  Being 3 inches off on a fairway and a one bag of fertilizer miscalculation going to matter?  A drone can do it quicker and provide photos of the turf as well.  My point is, if it is not needed for measuring accuracy for construction, actual land surveying boundaries or other legal reasons, drone businesses should have some leeway to let the user of the data make a decision if the data is accurate enough.  I think some surveyors see drones as an intrusion into their business and this is an effort to protect their turf :)

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@Cyclops55 loved the protecting your turf pun.  As we all work together to figure these types of issues out it’s important to acknowledge our standing in the conversation.  In other words I’m not a surveyor or attorney either but I share my opinions in the hopes of gaining a better understanding so that I can begin to ask a professional the right or relevant questions.  

This is a great conversation, @TLG Dan Inloes thanks for the great explanations and sharing your experiences.  This type of thread helps provide the layperson a great place to start from.  

2 hours ago, Cyclops55 said:

drone businesses should have some leeway to let the user of the data make a decision if the data is accurate enough.

I think they do.  Context of the application of the term “survey” is important. In your example even if your using a drone to survey an area of a golf course and your using the data to determine the amount of fertilizer needed for the “surveyed” area, the application of the data is for precision agriculture.  In your example you’d have to determine the restrictions of using drones for that application, for example you could probably use a drone to determine the amount of fertilizer required but probably not use a drone like a crop duster to apply it.  

 

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Clients:

@Av8Chuck brings me to my next point. As I've said above, this will vary from state to state, but my general rule for drone businesses is that you have two client audiences: Those that are surveyors and every body else. In some states, it could be surveyors, engineers and everyone else, but you get the picture. If your data falls under the category of land surveying or engineering, meaning that the work is blanked under work that requires civil standards, your working for a surveyor or an engineer. Period. Not a developer, not a construction company, a surveyor. 

If your calculating the area of a golf course to figure out a quantity for fertilizer, or the area of a sand trap, or you want to map out the course for pamphlets to give the golfers, or create an ortho of a property for a real estate agent, or calculate the volume at a gravel pit or a land fill, this type of work does not have standard associated with it. Is the 3d surface or ortho you create of the land fill going to be used to design a school or a bridge? Is the golf course owner going to take the ortho and use it to design a subdivision? Is the real estate agent going to use an ortho to design a detached garage or an underground pool? No. These are all tasks that fall under engineering and surveying and they know that. What your basically providing is an updated, super high-res google image, from that day, not 6 months ago when google flew over last. They can use an ortho as they would use a google image ripped off of google earth.  Or, like in my land fill example, your providing them a volume calculation, a number, not a map. 

To put it even more clearly into focus, if the coordinates mater, if the project is being tied to an actual coordinate system, your using ground control and you need a surveyor to do that. You can't create survey grade data with out the help of a surveyor. This means that if the client doesn't care about the coordinates, its not survey grade data and the need to set ground control points is void, thus not being held to any standards and in the eyes of a surveyor or engineer, you've create a "pretty picture", not a map.

If the client wants survey grade data, hire a surveyor to set ground control and convince him that you know what your doing and that your data falls within his tolerance levels and comfort levels. It will cost more, but you get what you pay for. The PLS is putting their career on the line and he only signs and stamps data that's true and correct. My recommendation is that if you want to be creating survey grade data exclusively, you need to partner with a surveyor, or, like a talked about in my previous post, become a temporary employee on a project by project basis so that your covered under the PLS's "responsible charge", or in other words, his professional liability coverage. 

But I digress. Most of your clients don't care if the data has correct geospatial coordinates or coordinates in the middle of the Atlantic. They don't care. It doesn't need to be that accurate for what they're doing. Thus, you do not have to uphold a standard of accuracy and should be on the right side of the law if your data is ever questioned. To cover your bases on this, I wouldn't put a north arrow on it or a scale bar. Do not impersonate a map or a survey. Do not imply that the data has any coordinates at all. You can provide a volume with units, but you will also be providing the accuracy of said volume, like +/- ten cubic yards or feet or, pick your units. 

Now, not being "survey grade accurate" doesn't mean that your data isn't good, it just means that its not good enough to be considered "survey grade" or "engineering grade" data. The internal accuracy of your data will most likely be very tight in relation to itself regardless of weather its tied to real world ground coordinates or not. Like a said before, your creating pretty pictures with lines on them. If your client needs data that they will be making measurements on that need to have a tighter tolerance than you can provide with out GCP's, they need coordinates and they need a surveyor. 

I hope this sheds some light on the questions regarding who your clients area and what kind of data you're going to providing them. This is still a fuzzy topic and I don't claim to be stating law. You need to do your due dilligence with your own states laws before you get too far into your business endeavors. This is just my opinion from doing local research, talking to surveyors, talking to the state board, and talking with clients in the state of Idaho and Oregon. 

Please let me know your thoughts on this because the more minds working together, the more educated we all get. 

Again, that's my 2 cents. 

Cheers for now!

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On 1/21/2018 at 11:55 PM, TLG Dan Inloes said:

If your calculating the area of a golf course to figure out a quantity for fertilizer, or the area of a sand trap, or you want to map out the course for pamphlets to give the golfers, or create an ortho of a property for a real estate agent, or calculate the volume at a gravel pit or a land fill, this type of work does not have standard associated with it. Is the 3d surface or ortho you create of the land fill going to be used to design a school or a bridge? Is the golf course owner going to take the ortho and use it to design a subdivision? Is the real estate agent going to use an ortho to design a detached garage or an underground pool? No. These are all tasks that fall under engineering and surveying and they know that. What your basically providing is an updated, super high-res google image, from that day, not 6 months ago when google flew over last. They can use an ortho as they would use a google image ripped off of google earth.  Or, like in my land fill example, your providing them a volume calculation, a number, not a map. 

@TLG Dan Inloes That brings me back to my original post.  You don't need a surveyor to sign off on how many bags of golf course fertilizer you need if you get the data from drone mapping.  As drone data is used for more things there will have to be new laws and standards developed on how the data can be used. 

Dan, curious to. know what you think of Propeller Points.  Basically GCP type GPS reference points that have GPS in them.  I don't know much more about them, but Drone Base sent out something asking pilots if anyone had them.

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49 minutes ago, Mike Cumbie said:

Dan, curious to. know what you think of Propeller Points.  Basically GCP type GPS reference points that have GPS in them.  I don't know much more about them, but Drone Base sent out something asking pilots if anyone had them.

Hey Mike, 

My thoughts on this is that if you're needing ground control to get more accurate data, you'd be working with a surveyor which will be setting GCP's for you with his survey equipment. The internal accuracy's of the data is already very accurate in relation to itself. If you introduce GCP's to the project, you then introduce real world coordinates. If you're working in real world coordinates, the likelihood that your data will then be used to "measure" stuff goes way up. The fact that your data has been corrected to reflect georeferenced ground coordinates is enough to be considered survey grade. Unless you''re working directly for a surveyor, you run the risk of stepping on the toes of surveyors which could in turn get you sued. 

If you need your data more accurate than what the raw images can create without GCP's, your working for a surveyor. Why drop $6k on Drone Base Propeller Points when you're going to be working with a surveyor that has a $60k GPS that can set better GCP's? Thats my point. If you need GCP's, you're going to be working with a guy that can set your GCP's for you. If you don't need GCP's, you're not working with a surveyor so why spend $6k on equipment that would constitute survey grade data when you're not a licensed survey? 

See where I'm going here? Its unnecessary. Maybe give me an example of when you think you'd need GCP's when the client is not a surveyor?

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1 hour ago, TLG Dan Inloes said:

Maybe give me an example of when you think you'd need GCP's when the client is not a surveyor?

Dan, 

One example,  DJI's uavs rely on the barometer to determine it's height above  take-off point.  This relative elevation is saved in the image exif data for where the image was taken.  The barometer tends to shift over time and the result is usually that he drone starts loosing altitude gradually as it flies a grid capturing images.  However,  the elevation recorded to the exif data in the images remains constant.  So,  you end up with a DSM that slopes from one end to the other where no slope exists.  Not a big deal if you just want an ortho.  But if you want to measure stock piles, it can obviously make a difference.  

If the property already has fixed monuments that can be used, or if the uas service provider sets some less than perfect ground targets either with Aeropoints or Reach modules (as examples) to overcome the known deficiency in the dji uav.  The resulting DSM can gain a descent improvement over using no ground control.  Even though "survey grade" results are not expected.

RTK_alt_vs_DJI_alt.png.52643118042f1162fbc80f9be2ad3b61.png

Edited by Dave Pitman

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1 hour ago, Dave Pitman said:

But if you want to measure stock piles, it can obviously make a difference.  

I agree that it would make a slight difference. Very slight. Keep in mind that most photogrammetry software packages calculates an error percentage when calculating volumes. I've never seen an error accuracy greater than ±3% from pix4d and I've done about a dozen stock piles. Its very common to see a surveyor note ±10% on volume calculations on stock piles, especially big, illformed piles when they're collecting data with a GPS system, which is most common. Unless your using a laser scanner, photogrammetric methods derive a more accurate data set then the means a typical surveyor would employ. Typically a GPS system. 

So, you might see a difference of 0.1inches in your ground sample distance (GSD) with a 10' altitude difference from one side of the site to another, but with an overall error of ±3%, if you take into account a 0.1" GSD variance, you might be looking at a different of 1 cubic yard or less between using GCPs and not using GCPs. Usually the client wants to know a volume to the nearest dump truck load or so, not a tablespoon. Again, is it necessary to drop 6k on GCPs to dial it in that much? In my opinion, no. Furthermore, Why give a surveyor an excuse to call you out? He's already pissed that he's didnt get the job, but now he has a foot to stand on in terms of accusing you of providing survey grade data without being licensed. 

Also, from what I've read, the barometer on DJI drones are backed up by the internal GPS and corrected in real time as you fly to account for pressure variances. 

Edited by TLG Dan Inloes
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So far, the volume estimates I have done are with no ground control.  To your points, the clients so far are not at all interested in absolute accuracy. 

My point, I guess is that I am hesitant to basically say that I will not try to make my data as accurate as I can within the budget restraints of the particular project solely on the basis that if I try to do my job better, that means I'm trying to be a surveyor.  Even though I have no interest in crossing the line into what the law defines as deliverables requiring a surveyor's lic doesn't, IMHO mean I must not try to do the best I can with what I am doing.

I'll give you another example.  I provide ortho imagery for auto accident recreation.  I place ground targets and use a tape to measure between them.  I don't even do the processing on these jobs.  Just send in the image set with the target distances.  The client uses the targets and their relative distances to fine tune the ortho so that they can measure horizontal distances within the ortho to be used in court.  Pix4D calls these "scale bars".  So, while not GCPs, this is clearly going beyond just flying around and taking what you get.

The graph in my last post was a comparison of the elevation track as recorded by a dji P4 and an Emlid Reach module while flying a typical grid.

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