🎈 Public Lab: NDVI with Canon A2300, APM Hexacopter DJI550, Help

NDVI with Canon A2300, APM Hexacopter DJI550, Help

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:

The pink photos are infrablue photos taken with a camera that was not custom white balanced. It would probably help to do that procedure.
The pink photos were taken with a camera with a Rosco #2007 filter replacing the IR block filter. I guess you put the new filter on the inside.

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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Andres,

CHDK settings: It appears that you have the synchronous camera triggering working, so of the other CHDK settings for aerial photography the most important is probably shutter priority mode to keep the shutter speed high (~1/800 second). This is mentioned here and described here, but I think newer versions of CHDK work differently.
Having the Rosco filter on the outside is fine, but it is not protected and not shaded from the sun (that's okay for vertical shots).
The Rosco filter will give you a decent NIR image in the red channel. A piece of exposed, developed color print film (or unexposed developed color slide film) is a very good NIR filter -- it blocks most visible light and passes lots of IR. But it is not as optically clear and passes less NIR than a good Wratten 87 filter. I'm not sure whether Rosco 2007 or exposed film is a better NIR filter.
Fiji tutorials: That would be a great thing to have. Installing Fiji seems to be pretty easy, and installing Ned's photomonitoring plugin is described in Ned's guide. Using the plugin is also described in Ned's guide, but it would be really helpful to have a video tutorial for that (especially on making the text file of photo pairs). Fiji and Ned's plugin are incredibly powerful tools for processing VIS/NIR pairs or Infragram photos, so it is worthwhile taking the time to figure them out.

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Great, I have a lot to read ! I have Fiji and the plugin running,,, was able to run the plugin with one picture and with a directory with 2 pictures... but I´m doing something wrong...

I´m not getting nothing similar to the images that you show me... i try choosing red.red and red.blue as visible light and NIR... I also try making a directory with the 2 images from the 2 cameras, but on the output i get the same process for each file, so its not doing anything between the 2 pictures, just doing the same process for each of them

can you tell me the steps that you follow to process the image that you show me ? Did you use 1 or booth images ?

Thank you!

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The main reason your results differ from mine is that you did not have the home-made color lookup table I used. That lookup table is now available here (at the bottom). Here is the dialog box for processing the single (pink) displayed infrablue photo into NDVI and NRG:

Here is the dialog box for processing VIS/NIR image pairs into NDVI and NRG:

Changing some of the parameters in the dialog boxes can have dramatic effects on the results.

When you click OK in the box above, you will be asked for a text file of the image pairs. That file should be in this format:

L:\Infra\TestPhotos\Andresc4\NIR\IMG_0093b.JPG, L:\Infra\TestPhotos\Andresc4\VIS\IMG_0093a.JPG L:\Infra\TestPhotos\Andresc4\NIR\IMG_0152.JPG, L:\Infra\TestPhotos\Andresc4\VIS\IMG_0152a.JPG

One of the options of the plugin allows you to create a text file by inputting directory locations and other things. Sometimes I can figure out how to make that work.

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Sorry Chris, where are you getting the dialog box for processing VIS/NIR image pairs into NDVI and NRG menu from ? ( the second screen that you show me ) When i go to Plugins, PhotoMonitoringPluginMaster/src/ y have 4 options List images Register Images Create NDVI from image Create NDVI from Dir...

already save the lut file, now is listed

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NDVI with Canon A2300, APM Hexacopter DJI550, Help

Questions and next steps

23 Comments

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