Sorry for the late reply. Let me answer your questions in the following lines:
- Distance - Can the same software be used with one camera placed 6 inches above 1 plant, and another 24 inches above a dozen plants?
Yes! that is possible. However, in terms of computational cost detecting a dozen plants and following their growth would require more computer power, memory, etc. At the moment, this is still OK within the capabilities of the Raspberry Pi. Nevertheless, is something to think about when you design system with low-cost specifications.
- Hardware - Minimum megapixels, wide-angle, does it have to be a USB camera?
I have the impression that cameras with 1 ~ 2 Megapixels would work OK (didn’t test it though). However, cameras with 3 ~ 4 Megapixels would be able to detect more information, which is interesting when you are trying to analyse plant health, topology, etc. Wide-angle cameras are good when you have a big tray (rectangle-shaped) with plants. However, for the PFC a normal camera would work fine. In our case, we just wanted to have a consistency in the hardware we used for all our devices (PFC, Food Server, etc.). USB cameras are cheap and convenient. In addition, they are very easy to integrate with ROS. I am wondering what other types of cheap cameras are you considering?
How feasible is it to start using CV to tell us other things about the plants. I know these are all very far out dreams, but I'm curious if you think they have potential down the road.
- Lifecycle - Alert when seed germinates, flower formation.
There is already code in the openag_cv repo that would measure the plant width and count its leaves using an OpenCV “blob detector function”. It is a piece of code you can customise for your own plants. However, this is still experimental code. For instance, we need to integrate it in the “official” branch of the PFC code.
- Disease Detection - Notice changing colors on leaves, mold formation, perhaps even pests
Yes! The possibility exists. However, we are exploring novel approaches of how to solve this problem. You should take a look at this master thesis: http://scholar.colorado.edu/csci_gradetds/124/
- Sensor Replacement - I spoke with you at the Media Lab about this concept quite some time ago for measuring PH. I'm curious if we could ever use a camera to read the PH of a manual PH test/strip like in this studyhttp://www.iaeng.org/IJCS/issues_v38/issue_3/IJCS_38_3_11.pdf. I think this would be a really cool way a school who often times prefers to have some sort of manual interaction to also have a simple, and yet accurate method of data entry (leave strip in a specific spot on reservoir for camera to read later). I can elaborate more if this is confusing, I'd love to more about the direction you guys are going in and what you see the potential and quick wins to be especially in terms of the MVP because that will have minimal sensing abilities to begin with.
We started a project about how to measure pH with computer vision techniques. Right now, we are still evaluating the conclusions of this study. We took a different approach from the paper your mention. I can give you more details in a couple of weeks.