Hello, I'm new on the community, i have been reading the site for a few weeks and i just decided to join the community to share the project that I'm working on, basically i want to start using areal photography to control some fields. I have experience in UAV Drones ( multirrotors, and now im working on a small plane ). I work with APM2.5 + Mavlink. The drone its working just fine, I was able to complete successful missions, now Im stuch with the NDVI calculations
I bough 2 Canon A2300, i remove the Ir filter and added a Rosco2003 Infra Blue, bouth with CHDK and a remote usb trigger. I have some photos that i took from my firtst mision,,, im not over a real field, so there is no much vegetation to analyze
https://www.dropbox.com/sh/zvtyke3wpdtw4pt/9SyAeR6sF8 ( UAV folder )
I follow the steps on this video.... https://www.youtube.com/watch?v=Sfic43qRHqk
but im not quite happy with the results... and i having a hard time to align the images in photoshop! The cameras are new, same settings, same picture from the same angle, and the lens distorcion seems quite different. I thougth I made a mistake and I left one of the camera with more zoom, but i double check and still, cant align the images. Already try using PTgui, but still no success.
I would like to request some help regarding this topics...
A) Is there any opensource software to align the 2 images one over the other one ? B ) Is my NDVI calculation correct ? i don´t see the results ... is there any software that realizes this task easily ?
Questions and next steps
Regarding new steps on the project,,, im would like to use 2 exact RF cameras used for FPV, and use 2 different Vtx and Rtx to receive the video on a laptop, with 2 different usb capure card i think it will be possible to write a shader and to get the calculation in realtime... im a vvvv user (vvvv.org)
Well thats all, i hope to get some help from the forums, if any of you need help on vvvv or APM please let me know, or write me on my persona email ( mynewpixel.com <-- here is my email )
23 Comments
Andresc4,
Your UAV photo pairs are great quality. They are sharp and rectify with each other easily. I used Ned's Fiji plugin to align the pairs and make NDVI images which look biologically meaningful.
Above: NDVI using the red channel from the normal RGB photo for visible light and the red channel from the infrablue photo as NIR.
Above: NDVI from the single infrablue image using the blue channel as visible light and the red channel as NIR.
I made some assumptions about your photos:
Fiji and Ned's Fiji plugin are free and can process single camera infrablue (Infragram) photos as well as dual camera (VIS and NIR) pairs into NDVI and false color IR images. It's too bad you were led to the Photoshop procedure, which is way harder and less precise than Ned's plugin.
If you are going to use two cameras (one for VIS and one for NIR), you will get a more pure NIR channel if you replace the IR block filter with an IR pass filter like the Wratten 87. But then you will not be able to get NDVI from one camera. For a one camera system that provides a pure NIR channel, use a Wratten 25A instead of Rosco #2007 and the blue channel will be very pure NIR (use the red channel for VIS).
The FPV video cameras you plan to use might have CMOS sensors which handle NIR light very differently than CCD sensors. So be prepared to do some testing. For example, I have not heard of anyone using a Wratten 25A filter in a CMOS camera. It's wide open territory.
It looks like you are off to a good start.
Chris
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Hey Chris thank you for the quick reply! , the photo looks great! , and you were right, i did not use white balance I have the camera just with CHDK,,, can you point me some links on which are the best CHDK settings for NDVI ? I read that i need to use manual White balance with Dayligth settings, but I´m sure that are many other things to set ( ISO, Focus, Raw... )
I'm using 1 layer of Rosco 2007 on the external side of the camera,,, it should be inside ?
I'm planing to use 2 cameras, one for visible ligth and the other for NIR, on the NIR camera i have the rosco... to be honest if i order another filter i need to wait 2 months until the mail delivers the package to my house, we have a huge crisis in Argentina regarding shippings and packages from other countries.
Regarding the FPV video setup, I ask a friend to help me with the vvvv code to compile the images, he will give me an update soon... the good news is that we have CCD cameras with and without IR filer... i guess we will get 2 cameras without IR filter and add the spare filter that we have from the Canon one,.,,, i will keep this post updated on this topic.
Regarding Fiji... can you show me some tutorials regarding the steps to install the plugin and get the NDVI final results ?
Andres
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