If you’re testing the amount of ammonia, nitrates, or just the pH of a pond, pool, or aquaculture setup, there’s two ways to do it. The first is with test tubes and chemicals: put some water in the test tube, add some chemicals, and match it to a color card. The second option is with expensive sensors.
[James] has a better idea. Since pumps, RGB LEDs, and light sensors exist, he’s building a reagent robot that will be able to measure ammonia, chlorine, nitrates, and pH without purely electronic sensors. The idea is to fill a clear container with water, add those fancy chemicals that come from aquarium supply stores, and measure the color of the water.
Right now, [James] has a bunch of stepper motors, valves, and solenoids all working together to pump water into his clear container. The next step will be to mount some RGB LEDs, a light sensor, and calibrate everything so colors can be measured.
It’s a great idea for electronic monitoring of aquaponics, ponds, and aquariums; those indicator chemicals are pretty inexpensive compared to electronic sensors, and once [James] has one measurement/reagent working, adding another is just a matter of putting in a few more tubes and pumps. You can check out a video of the progress so far below.
scans of large objects (including people) come out looking noticeably faceted. [Luis] came up with a work-around that results in a much finer detailed scan. Instead of scanning an entire person with one scan, he would do 4 separate scans. Since each individual scan can support 5,000 faces, the resulting merged model can be up to 20,000 faces. Check out the comparison, the difference between the two scanning methods is quite noticeable. 
