Hello everyone.
We are looking to develop a UAV for crop surveying where the stress identification will be performed mainly by an infrared camera. We are not looking to spent too much money on the sensor and have been considering modifying a normal RGB camera. Are there any major advantages for using an off-the-shelf infrared camera vs getting a normal camera converted?
Thanks!
Replies
What region of the infrared are you working?
NIR(700-900nm), SWIR(900-2500nm), MWIR(2.5um-7um), LWIR(7um-14um)
There are integrated solutions for all regions, with Visible sensors, Including Image Fusion.
You say you don't want to spend too much? Well that may be a real issue. To be successful, the imaging system is of the utmost importance.
The issue at hand is that off the shelf consumer grade cameras used are not designed for data analysis, they are made for taking pretty pictures. The senors used in consumer grade cameras are the lowest grade of sensor, Grade 3. These sensors have the most bad pixels and are made to the lowest of standards in quality and quality control.
There are Grade 2, Grade 1, and Military/Space Grade(probably more expensive for a single sensor than the house you live in?) Most good industrial cameras use Grade or Grade 2, never a Grade 3.
As well, the Grade 3 sensors are usually of poor low light ability, have noise in the images, have high Dark Current & Dark Noise, Small pixel wells, and low Dynamic Range, just to mention a few issues.
I have seen the consumer cameras converted using Dual Bandpass filters. A region of Visible up to around 600/650nm and a region of NIR from 700-850nm. Beyond 850nm Silicon based sensors drop off quickly in QE and spectral response, usually terminating around 1100nm. They all perform horribly even with such software from Pix4D and others. Again the sensors are not designed for this and will perform poorly. Seen it a number of times.
So, I guess it depends, do you want to do this professionally or are you doing this as a hobby?
Have a look at the attached images. This are prism cameras, designed for UAV use and for Agricultural data collection. There are also hybrid Multi-Spectral/Hyper-Spectral, and Hyper-Spectral available.
telecamere-multicanale02.jpg
telecamere-multicanale10.jpg
telecamere-multicanale01.jpg
Could you please provide a link where these prism cameras for UAVs are sold ? Because what you provided is the sensor only..
Thanks
Michal,
You are correct. One prism was without imaging sensors, the other two had the sensors attached to the output faces.
The prisms in the images were designed and manufactured by Optec, SpA(www.optec.eu). Complete prism cameras using Optec, SpA's arrays are integrated in to cameras built by Quest Innovations(www.quest-innovations.com). Currently every one is at the Stuttgart Vision Show in Germany.
Along with Aphesa(www.aphesa.com) and Awaiba(www.awaiba.com).
Contacts: Aphesa - Arnaud Darmont, Awaiba - Martin Waeny & Stephen Voltz, Optec - Giuseppe Cilia, Quest Innovations - Richard Meester.
I am a distributor in the US for all four companies. Since you are in Europe, you are are welcome to contact each direct.
I've been having good luck with Tetracam, if you don't need the ability to change lenses I highly recommend the ADC Micro (not the snap as you pay more for quicker shooting but lower res images). Also worth looking into is the set of sensors Fourthwing is starting to produce, they have a pretty nifty combined two camera sensor package that is tiny, (NIR, plus RGB) and I've heard rumors they are working on a four sensor camera package that includes a microbolometer (unconfirmed).
My current Agbot rig I'm running an ICI 9640 for Thermal and a Tetracam ADC Lite both triggered off a single pololu micro switch (had to add an optocoupler for the Tetracam but happy to describe the very simple circuit for that if you need help).
We're currently experimenting with analytics on IR and NDVI processed image layers. That I can't give you help on :D
The other thing to consider is that you need to do some calibration for different lighting (or the ability to do it in software) as the sun reflectance changes from day to day (depending on cloud cover and conditions. Especially if you are going to use the images like we do for measurement of changes over time.
I use a an off white queue card for each run I do (it came with the Tetracam) and I feed that in as a calibration image when I do the NDVI processing.
Hope that helps. For pics of my agbot see my build blog here:
http://eaglesviewaerial.com/?p=90
and here:
http://eaglesviewaerial.com/?p=103
Hi Paul,
Yes the Tetracam ADC is a nice piece of kit but it tends to be expensive. You are spot on about the calibration requirements.
Take care
My take is that there is a significant difference between a converted camera and something like a Tetracam. The Tetracam will give you 3 clean, calibrated (relatively) narrow bands. The converted camera will give you (typically two if one of them is NIR) broad overlapping bands that are not calibrated unless you go through the trouble to do that. The converted camera image is also recording through a Bayer filter. Most people seem to be interested in seeing how vegetation vigor varies across an image and if that sort of relative image is good enough for your application then the converted image is fine. If you go with a converted camera I suggest you use a red filter like a Wratten 25.
Dear Benjamin,
I have done some trials both with modified canon and Nikon.
The best result was obtained with Nikon Coolpix P6000. Removing the IR blocking filter is only one part of the work.
You must work quite a lot on a correct calibration and choosing a correct filter to put in front of your camera objective (or inside replacing the IR -best solution). Tetracam offers a quite expensive out of the shelf solution, but basically uses the same principle (Delgado).
See some results obtained: www.agriculturaluav.eu
Best
Marco
You can get quite far with converted normal cameras - the advantage is that all the r&d that goes into "regular" cameras works of you, if you go that route. If you compare the converted cameras that you get, for example, at MaxMax, to a dedicated solution, such as those offered by Tetracam, there also is a significant price difference. Something like a Tetracam product, on the other hand, might integrate better with your platform, but many people are happy with just dropping a modified Canon into their Fuselage.
The real question is the quality of the spectral data - how well does the filter harmonize with the imager. Don't know if the expensive solutions actually do have an edge or not.
Knut
-
1
-
2
of 2 Next