Question: what are the requirements of a camera for Filter replacement and NDVI imaging?

This is a good question, and not an easy one to answer.

Preferred characteristics of cameras to be converted to pure NIR or full spectrum (NIR + RGB):

Top priority

• The factory IR cut filter can be removed without doing damage to camera.
• The camera can be focused well after the conversion.
• Removing the IR cut filter does not introduce exaggerated lens flare (a hot spot).

Medium priority

• The camera is easy to disassemble in order to access the IR cut filter.
• The camera can be tested for focus without a long process of reassembly after removing the IR cut filter (because this might have to be done multiple times).

Preferred characteristics of cameras to be converted to single camera NDVI (NIR + VIS):

Top priority

• Same as above
• A custom white balance can be set on the camera (required unless some form of NDVI calibration will be done).

Medium priority

• Same as above
• There is an easy place to install a new filter in front of the sensor.
• If the new filter is installed internally, it does not introduce unacceptable optical artifacts.
• If a calibration procedure for NDVI is planned, recording RAW file format might be required.
• The camera is not a small CMOS camera like many webcams. These often don't work well, especially with blue filters.

Unfortunately, it is not possible to know most of these things without attempting to perform a conversion on a camera. Therefore, Public Lab encourages people attemping conversions to record their experience here: https://publiclab.org/wiki/infragram-convertible-cameras. This is a good list of cameras that have been successfully converted to IR and some that were not successfully converted. The list is aging and few cameras have been added in the last year.

It would be good if each of the entries on that page included a minimum set of particulars related to the above list.

Chris