NDVI Imagery and Drones - Resources?


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Hi all, got a great email from someone in our community and wanted to crowdsource a response:

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Alan, we're interested in determining how a UAS can assist in managing vegetation for terrestrial and wildlife management programs and for linear (poles and wires) corridor management, and for dam safety moisture content tracking. I understand NDVI imagery may be an option, but am confused by the huge variety of info on the web from vendors.
 
Where would you recommend we start looking to determine the clearest info to help us determine how and if UAS can help with these management programs, and what assets / software are the best value?

Thoughts?

I know Sentera sells a DJI upgrade package. And I've heard about companies like Agrobotix and Drone Nerds, the latter selling add-on cameras, but I don't have direct experience with either company. 

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  • 2 years later...

Ive been using NIR cameras on drones to generate NDVI imagery for farm management for about 8 years, and have done about 100 000 ha of NDVI mapping. The short answer is that I haven't found a really great platform yet at cost effective price. NDVI is also quite an art in of itself and needs a fairly good eye and understanding of the crop you are looking at. Most of the NDVI work I have done has been with a Sensefly Ebee with Canon S110 modified NIR camera. I don't particularly like the ebee platform and its let me down many times but I still keep just because it the camera that goes with it good and generates good results. 

I generally process with PIX4D and then work in Global Mapper to  calculate the NDVI and adjust the shader to display the right colours for the and various values generated by the NDVI. remember that the NDVI is simply an NIR image that has undergone and algarythm which assigns each pixel a numeric value somewhere between -1 and 1, usually to 3-4 decimal places, that correlate back to photosynthetic activity. There are however many variables that effect the values, such light intensity, cloud cover, soil moisture, etc. This can to a certain extent be calibrated using calibration plates or light sensors integrated into the camera such as on the parrot sequoia, but I generally find it easier to simply adjust the colours and value ranges manually to suite the crop and conditions in the post processing. It's not very scientific, but i effectively calibrate the crop to itself and am able to highlight areas of good growth and areas of crop stress more clearly and in a way that will make sense the farmer. 

I have tried the Sentera on phantom and was hoping that it would be a good option to replace the ebee, but I was very unimpressed with the results. the values did not make any sense to me and I had to go through various different software programs to get a meaningful result that at the end of the day, I didn't actually trust. 

I also don't like the Parrot Sequoia, as the RGB side is really bad and the resolution on the NDVI is very poor. I have also heard that one of the online NDVI processing companies is sueing them because of the poor results they get from this camera. 

I think the Mica Sense camera is about the best off the shelf option for NDVI and generates some very good results, but it is very expensive at around $9-10 000. 

I have ordered an Xmission drone from Specialised Agricultural Services (www.specialisedagriculturalservices.com) who are the XAG guys in South Africa, and will be testing it out as soon as it gets here and will let you know what the results are like. it looks very impressive as it comes with a similar type camera to the Micasense but works of  a RTK base station, and you can use the imagery to plan and execute crop spraying operations with the XAG crop spraying drones. check out the video at 

 

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Ross, I'm a mapping remote pilot with the state of Nevada.  I found your nvdi post fascinating and really appreciated your equipment comments. I'm impressed with the extent of your knowledge and flight experience.  I'd really like to get your advice on some RGB camera settings. Would you please email me at kenforestry@charter.net 

Ken

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I have a modified camera to do NIR work from Aerial Media Pros for my DJI Matrice 100 and I'm not happy with the results. First, to do NDVI work with this camera you have to fly first with the RGB then again with the NIR. I use DroneDeploy for mission planning and it isn't capable of using two images to create the NDVI, To do that, I used ImageJ - the process was time consuming and ripe for errors. I've never been able to produce an NDVI image that's made any sense to me using this technique. I'm looking at the MicaSense camera, but the one without thermal as it's about half the price. I've had just a little bit of time to use that camera when doing some trial work with OSU - I was much happier with the results. They actually made sense. We used Pix4D to process the images.

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