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"Spatially Speaking" is the official MAPPS blog providing information on topics related to the association and profession and MAPPS involvement with the issues.

 

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Just How Accurate is Your Drone?

Posted By Mike Tully, Tuesday, January 26, 2016

Unmanned Aircraft Systems (UAS) continue to influence the profession of remote sensing and mapping like few things ever have. Advances in computer technology, global positioning, and miniaturization have conspired to remove considerable barriers to entry. Many new practitioners are buying drones and providing these services and data for the first time. Much (not all) of the science and art of photogrammetry is now coded on a chip. These advancements enable new practitioners to provide a greater array of services to new and existing markets than ever before and fosters the misperception that “anyone can do it”.

 

New practitioners of drone-based remote sensing and mapping need to understand the fundamentals of remote sensing, mapping, photogrammetry. Typical deliverables like orthophotography, digital elevation models (DEM), contours, cross-sections, and 3D models depend on this understanding. Nescience of these fundamentals is certain to cause considerable pain, financial loss and compromises to public safety. This article introduces the fundamentals of positional accuracy to help new practitioners provide these services consistent with professional accuracy standards.

 

I have talked with several practitioners that did not know what “ground control” was or how to use it to establish positional accuracy. This lack of familiarity is not uncommon among novices. They may not know that positional accuracy requirements are needed, or that they are often assumed by the client. They may not know how to discuss positional accuracy with their clients, nor how to measure the positional accuracy of their data deliverables.

 

Professionals know that an accurate ortho (or DEM or 3D model) can look identical to an inaccurate one. Both are “pretty” pictures with lots of great detail but one has more intrinsic value for a greater number of uses than the other because it is more accurate.

It matters very little what the drone manufacturer says about the positional accuracy of its products. A combination of factors (and seldom a single factor) affects the positional accuracy of an orthophoto, DEM, or other derivative of remotely sensed data. Poor operation of the best drone can vitiate the positional accuracy of a deliverable. If a drone manufacturer claims their camera is accurate to two pixels for any given ground sample distance (GSD), the resultant positional accuracy for the orthophoto is dependent on each of the following factors. [The list below is not a comprehensive list of error sources but includes the major contributors of error.]

  1. the cameras inherent potential accuracy
  2. the stability of the flight
  3. the quality of the GPS data
  4. the quality of the inertial system (if the drone even uses one),
  5. the quality of the DEM used to make the orthophoto, and
  6. the type and quality of processing of the raw imagery into an orthophoto (this factor alone has several important sources of error from a “raw” to “finished” deliverable)
  7. the number and quality of ground control points

Each factor contributes some error to the ultimate positional accuracy of the final deliverable. The sum of all errors determines the measurable positional accuracy.

 

Understanding accuracy and accuracy standards sets your operations apart from others’. The American Society of Photogrammetry and Remote Sensing (ASPRS) is the major “standards body” for this profession. Their Standards for Geospatial Data reflect the realities of new sensors and digital data. They are “scale- and technology-agnostic”. That is, the standards apply to data produced at any scale using any kind of sensor today or tomorrow. They can be used to measure and report the positional accuracy of geospatial deliverables like orthophotography, DEMs, digital surface models, 3D models, contours, topographic mapping, etc.

 

Deliverables with good, consistent positional accuracy can be an important differentiator for your drone-based remote sensing business. Unfortunately, a main cost driver of geospatial deliverables is positional accuracy. More accurate data will generally be more

expensive than less accurate data. Profitability is highest when the required accuracy is not “over-engineered” and drives up costs.

 

What level of positional accuracy is achievable using today’s drone systems? Assuming “best practices” with a drone using a metric camera (most drones do NOT have a metric camera), high quality ground control, and solid production procedures (all difficult to achieve consistently) the best possible accuracy for orthos would have a root mean square error (RMSE) = 1 to 1.5 Pixels (GSD). Are these levels of accuracy achievable flying a drone with a non-metric camera and without any ground control?  Not a chance ... not today!

Because increasing accuracy comes at a premium it is imperative that the practitioner understand what accuracy is achievable from their drone “system”, what the client expects, and what is needed (this is often at odds with client expectations) to meet the deliverable's intended use. Because quality remote sensing data and services are difficult to deliver and need considerable expertise that is not yet programmed into the “easy button” many drone fliers are choosing to collect data and have established firms produce positionally accurate, irrefragable geospatial deliverables.

Mike Tully, Aerial Services, Inc., Cedar Falls, IA

Tags:  Drones  reality-check 

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MAPPS Minute - UAVs and Upcoming Events

Posted By Nick Palatiello, Friday, March 7, 2014


Check out this week's MAPPS minute to learn about MAPPS activities related to unmanned aircraft systems (UAS), recent news on the topic and upcoming MAPPS events.

court ruling announced March 6 may have a positive impact on the use small UAS/UAV. The FAA has appealed the decision. MAPPS is engaging stakeholders and partners and will provide education once more information becomes available on what this means for commercial use. MAPPS has recently engaged with the legislatures in Georgia, Iowa, Michigan and Maryland on legislative language regarding UAVs that would be harmful to the profession. 

MAPPS announced this week a Member-Guest breakfast to take place at the ASPRS Annual Conference in Louisville, KY. Members are encouraged to register and bring a prospective member to attend the breakfast. Our guest speaker will be Denise LaDue, U.S. Army Corps of Engineers - Louisville District, where she is Production Manager for the Inland Electronic Navigational Chart (IENC) initiative.  Ms. LaDue will discuss the Louisville District's surveying and mapping program and the IENC initiative. Register Here.

The early registration deadline is March 14 for the 2014 MAPPS Federal Programs Conference. Save on your registration today! A limited number of hotel rooms still remain in the MAPPS block. The Federal Programs Conference is a Members Only event.

Don't forget to educate yourself on the four issues MAPPS will take to Congress April 2 as part of the Federal Programs Conference. MAPPS will review Government and University Competition and Highway Bill (MAP-21) Reauthorization in the remaining two episodes of the "Legislative Issues" webinar series. 

Tags:  ASPRS  Drones  Federal Programs  Geospatial  UAVs  Unmanned Aircraft Systems  USACE 

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Thoughts from the AUVSI Convention

Posted By John Palatiello, Thursday, August 15, 2013



This year, for the first time, MAPPS had a presence at the annual convention of the Association of Unmanned Vehicle Systems International (AUVSI), held August 12-15 at the Washington, DC convention center.

Our participation stems from a lunch meeting MAPPS President Jeff Lower, Assistant Executive Director Nick Palatiello and I had with AUVSI President Michael Toscano, Government Affairs Manager and General Counsel Ben Gielow and State Government Affairs Manager Mario Mairena at which a liaison between our respective organizations to work collaboratively on legislation and policy issues was discussed.  As a result, Mairena spoke at the MAPPS Summer Conference in Maine in July and I was invited to speak this week at the meeting of the AUVSI government affairs committee.

MAPPS has opposed restrictions on civil, commercial use of unmanned aerial systems (UAS), which are likely to soon become a commonly used platform for aerial geospatial data acquisition.  While working with AUVSI to defeat onerous anti-UAS legislation, MAPPS has also sought and in some cases succeeded in securing exemptions for mapping operations.  (See, for example, in Congress S.1057, Georgia SB 200, and Idaho SB 1134.)

A Congressional staff panel discussed UAV issues with MAPPS members on Aug. 14

MAPPS also hosted a policy luncheon at Microsoft’s beautiful technology and innovation center, just one-half block from the DC convention center.  Government Affairs Manager John Byrd assembled an outstanding panel of key Congressional staff with direct involvement with UAS-related legislation and policy.

There were a number of "hot topics” discussed during the conference. I attended a session on privacy that was broadcast by C-SPAN.  I was able to comment on the MAPPS membership and our interest in UAV and privacy issues, which can be seen at 1:23:30.

There was discussion at the MAPPS luncheon and in other venues that the word "drone” should be stricken from our vocabulary.  This may be a difficult term to overcome. However, we can paint a better picture for the practical uses of UAVs for surveying and mapping. If your firm is working with a UAS outside of the United States or with a domestic partner with a COA and  have examples of how systems are used for agriculture, oil and gas, or other applications that highlight the safe and responsible benefits of the emerging technology, MAPPS would like to know.

Another topic that attracted considerable attention is the ever-present specter of unfair competition, manifesting itself in various forms.   Several MAPPS members and others in attendance at the conference expressed frustration that certificates of authorization (COAs) are being granted to government agencies and universities while the private sector awaits the Federal Aviation Administration plan for civil, commercial COAs for UAS, as required by Congress in sections 332-336 of the Federal Aviation Administration Modernization and Reform Act, Public Law 112-95. There is concern that agencies and universities are acquiring UAS and utilizing them on projects that can otherwise be accomplished by the private sector. Many MAPPS members recall a Predator from the Customs and Boarder Patrol being diverted from its core mission guarding the U.S.-Canadian border to capture data on a flood in the Red River in North Dakota and Minnesota, resulting in a loss of business for private geospatial firms under contract to the Corps of Engineers, USGS, and other federal mapping agencies. Moreover, while current law and regulation permits private citizens and firms to operate UAS for a "hobby”, there is no effective enforcement to prevent abuse of such authority for commercial purposes.  Finally, several conference attendees see an emerging problem – the "dumping” of an estimated 7,500 surplus military UAS to government agencies in the U.S. resulting from the draw-down of combat missions and activities in Iraq and Afghanistan.

At the MAPPS luncheon, Congressional staff presented views on the competition issue, including the need to assure agency conformance with the Economy Act and the Federal Acquisition Regulations (FAR) that regulate agencies’ authority to perform services for other agencies.

In preparation for the AUVSI Government Affairs Committee meeting, John Byrd reminded me the first presentation on UAS at a MAPPS meeting was at the Winter Conference in Palm Springs, California in 2008.  Our association has continuously kept the membership appraised of UAS policy, technology and opportunities for more than five years.  
 
It goes to show that "in an economy where you are counting every dollar, it is good to know you can count on MAPPS” is not just a slogan, it is a fact.

Tags:  Drones  Economy  FAR  Government Competition  Privacy  UAV 

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