Drones and Survey Accuracy

[LS7773]

I am looking into using drones for ALTA survey work. My big question is - is the data accurate to meet ALTA requirements. Most applications that I have read show drones being used for volume calculations over large areas. Any information would be greatly appreciated.

Thanks

[pls7809]

Following.

[Paul Goebel]

The Minimum Standard Detail Requirements For ALTA/NSPS Land Title Surveys address this in Table A, option 15. There is no specific accuracy requirement for "remote sensing and photogrametric mapping. The term "appropriate and acceptable accuracy" covers it.

If the surveyor (or their consultant) understands the accuracy they get from the drone, I see no problem with using it for an ALTA/NSPS survey. In my experience, the accuracy can be better than traditional airborne photogrametry.

The FAA has requirements that could prevent the legal use of a drone for an ALTA/NSPS. For example, drones can't be operated over humans not involved in the flight operation.

[pls7809]

If you're using a drone to show a building corner crossing a PL by a couple of tenths or less, I would say that you are using the technology for the wrong purpose. If you're using it for just background topography and to show surface utility locations and other items on the property and then using field survey data for locating possible encroachments, then I think that is a great application for it. It all depends on how tight the control is that is used to control the photography, same as any aerial mapping really.

[Seosurveyor]

Hi all,
We are in the process of developing a complete system for this exact purpose. You can visit our beta site at http://www.unifli.aero. This will be a field to finish tool for Surveyors to enhance productivity.
Like you we searched avenues to utilize UAV's to enhance our surveys but only encountered elaborate photo stitching software. Don't get me wrong the current offerings are amazing and revolutionary. This brought the birth of Unifli!
We are a bifold company. This meaning, (1) we custom build the UAV's with on board survey grade GPS. This is via Septentrio GPS solutions. Our PPK methods allow each photo to be processed and obtain a geocentering of 8-15mm accuracy ellipses. (2) our subscription cloud based service allows you to process your missions once uploaded. Once processed you have access to a variety of deliverables (I.e. orthphoto, 3D model via Sketchfab, NVDI, DEM, contours, quantities and GRP's). After that we have CAD processing.. simply highlight the area you would like mapped and agree to the price (based on area, topo, spot elevations and complexity) and the CAD planimetrics are typically produced within 24 hours. Pricing is a fraction of traditional aerials and reduced field time with higher resolution photos.
For accuracy we use GRP's (Ground Reference Points) rather than GCP's. Our processing does not adulterate or stretch the photos to fit control points. The GRP's allow you to pick ground points and receive relative errors between the photo points and actual shots. This helps to achieve ASPRS standards for residuals.
This is to complement your ground survey data and to enhance safety and reduce field time hours to help increase the bottom line.
We are about three out from official launch but exhibited at the CLSA conference and received amazing input from the attendees. Please let me know if you have any questions and I'll do my best to answer.
Cheers,
PLS 7526

[hellsangle]

Stop callin' 'em drones - that's what John Q. Public calls 'em!

Phil - Sonoma

[LS_8750]

So long as we know we are from a "known" point we are all good. A known point shakes out noise. What is a "known point" with GPS? There is always noise.

Drone photogrammetric point clouds aren't all that dense to say pick up a tight building corner when you might most critically need one. You might need some field verification. What critical components should you verify? There are office tasks that go with point clouds not consistent with typical cad.