Hi Roolark -

This sound like an interesting project. I hope you keep us posted with your progress. I think there is a lot of value in pairing Landsat imagery with DIY aerial photography. There is no doubt that DIY aerial cameras can be used in scientific research if rigorous methods are used. Effectively what you are trying to do is downscale or disaggregate the information in the Landsat signal to get information at a finer scale. If you accept that the Landsat data is of high quality then your task is to determine how the energy in a pixel is distributed within a pixel. As you mention, an important step in this process is to accurately align the aerial images so they are coincident with the Landsat image. In addition to using automated classification on the photos you might want to try visual/manual interpretation.

In my experience it is still quite cumbersome to use automated classification methods with uncontrolled aerial photos. If you want to try automated classification it will be best if you can constrain as many image acquisition variables (flying height, camera orientation, time of day/solar angle, exposure settings...) as possible. The low spectral resolution of the PLOTS system is (nearly) the least of the limitations.

All the best,

Ned

Ned,

Thank you for your interest and input. There are some details I'm still working on putting together, to include in the research note. I haven't been able to obtain reasonable imagery yet because the wind has been uncharacteristically calm here in Albuquerque (for kites) and I don't yet have a balloon.

I plan to collect my aerial imagery around the same times and dates as the Landsat 8 imagery I will be using. I will also be performing the appropriate dark-object-subtraction atmospheric correction on the Landsat imagery.

The reference vector point/polygon classification file I plan to use, for comparison to both the Landsat and kite/balloon imagery will consist of both heads-up digitizing AND in situ observations. With the field observations, I may be able to borrow our department's field spectrometer too, which would be very useful in measuring the spectral accuracy of the NDVI (and NDSI) infragram on vegetation and snow for features large enough to be discernible. Alternatively, I could use a portable (offline) implementation of the PLOTS desktop spectrometer for this purpose... although that may require an accuracy assessment of that product, in order to use it for accuracy assessments of the others?

I have a reasonably accurate GPS device that I will be attaching to my imaging rig, and I can coordinate the seconds between measurements to closely match the CHDK image intervals, in order to discern location and elevation of the rig. Unfortunately, I don't know a really great way to determine exactly what the flight altitude of each picture will be, but the GPS should give me at least a rough estimation.

If you have any other suggestions, please let me know, I'm all ears. This is for my departmental honor's thesis, and as I mentioned in my research note, my ultimate goal would be to use these tools (if practicable) for conducting further environmental research for graduate school.

Collecting you imagery so it coincides with Landsat 8 imagery is a good idea. MODIS acquires images at roughly the same time as Landsat so that's another good reference source for calibrating the Landsat and aerial images. Using a field spectrometer to calibrate you camera for reflectance measurements is also a good idea. I'm not sure how you could use the PLOTS spectrometer for that since it only provides relative measurements but maybe someone else has pointers.

For the camera height the absolute height isn't as important as taking all of your photos from roughly the same altitudes above ground level. Geotagging your photos with a GPS is a good idea though. If you take a photo of your GPS receivers clock on the screen you can use a program like gPicSync (https://code.google.com/p/gpicsync/ to geotag your photos.

When you go out and take photos I expect you'll make some new discoveries and will have additional questions. Feel free to post your questions to this forum or contact me via email.