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Can anyone advise me about the problem with vertical GPS values on DJI units? The horizontal values seem to be just fine. We have an Inspire 1 and an Phantom 4 Pro. We have been using them, along with DroneDeploy and Pix4D, to map wetland vegetation for wetland restoration projects in Florida. The problem arose when we started combining imagery with survey to create and deliver 3D models to our engineering colleagues. Both UAVs report accurate altitude to the RC, but the EXIF tags tell an entirely different story: A photo taken at ground level (let's say, 65' above sea level), is tagged with an elevation of -88.0 (no indication of what the units are, but .5 units represents about 100'). If we fly 100' into the air and take another picture, it now reports an altitude of -87.5 units. Per the DJI helpline folks, we've tried recalibrating the unit right before flight, and that doesn't seem to make a difference. Unfortunately, the images captured indicate that, rather than 200' over the levee (which is about 70' on the NAVD88 datum), the image thinks that it was captured from a position 20' or so below the roadbed. Flying another 100' or 200' up still doesn't get us above ground level. So Pix4D and Simactive both have trouble resolving this, and even manually editing the GCPs (at least in Pix4D) doesn't seem to fix things. DroneDeploy does a decent job of creating a model, but it's not georeferenced, and that's part of scope. Plus, 1) I'd like a more detailed model than they generally provide, and 2) my management will not support the subscription upgrade necessary to use GCPs, especially since we already purchased a license of Pix4DMapper. Dishing out $20K for an RTK unit is not on-budget for a few more years, so let's just assume that's not a solution. Besides, we don't need centimeter accuracy for the flight, just for the solution after the GCPs are incorporated. Just being within a few meters of reality (as advertised) during flight would be fine. We could probably write a python script to write pressure altitude values to the GPS field, but that seems like kind of a sloppy workaround. Any other ideas? Does anyone have a buddy at DJI who might fix this? Kindest regards, - Bill William E. VanSickle Professional Geographer, Commercial Remote Pilot GIS Analyst III, Office of Information Technology St. Johns River Water Management District P.O. Box 1429 ● Palatka, FL 32178-1429 Office: (386) 329-4580 Email: firstname.lastname@example.org Website: www.sjrwmd.com Connect with us: Newsletter, Facebook, Twitter, Instagram, YouTube, Pinterest
Hi students! Just finished listening to this podcast episode and thought you'd enjoy. Feel like I have a much stronger sense of what Drone Deploy is about...small team, about 20 people, doing some great work in the mapping / modeling part of this industry. http://droneradioshow.com/three-things-we-learned-from-ian-smith-of-drone-deploy/ @Trevor - Icarus + @Lewis@IcarusAerials think you guys would enjoy in particular.