Setting up for filming
Experiment Setup - Video
To start an experiment, we have a few steps as illustrated in the video,
• Put tank into reservoir,
• Put fish into tank,
• Lift tank out of reservoir,
• Start videotaping.
The purpose of the tank is to house fish for videotaping. The size of the tank has to be large enough to let fish display normal swimming motion. The tank should contain only water, without any air on the top because water wave will distort the camera view on the fish. The tank should also be capable of water recycling, i.e. let fresh water pump into the tank and old water drain out, to guaranty the oxygen level in the tank water. General Configuration
(1) Tank Top, (2) Bottom Holder, (3) Lifting Handles, (4) Draining Channel
The tank top is made of glass and measures 42.3cm×17.3cm×18.6cm. A piece of blue colored material is attached on the back plane to form a unique colored background. The color of the material is chosen to be the furthest away from the fish body color (yellow swordtail in our experiment). This makes the image processing part easier. Eight black plastic straps are attached on each edge except the edges on the bottom. The function of the straps is to make a clear boundary of the tank area in the camera footage.
The bottom holder is made of a number of different materials. The purpose of the bottom holder is to support the tank top and the water in it. The bottom holder can carry shadow water, and the bottom of the tank top is immersed in the water. This can seal the water in the tank top. We attached some insulation foam on top of the bottom holder and a piece of blue colored material on the insulation foam to make the background. The bottom holder also has a “water pumping in gap” and a “water draining out gap”. In an experiment, fresh water is pumped into the tank through a tube and the “water pumping in gap”, at the same time old water drains out from the other side of the tank through the “water draining out gap”. Then, the water drains into the boundary area and leaves the bottom holder via a small notch (see the following figures).
To carry the tank top and the bottom holder easily, we made a pair of lifting handles. The handles are made of aluminum material and connected with two wires. To carry, the bottom holder is seat on the wires and we lift the two handles by hand.
The draining channel is to carry the old water drained out from the tank, and lead it to a water reservoir.
Part of the design can be further improved. In our experiment, putting fish into the tank is somewhat tricky, especially when putting multiple fish into the tank. The fish already in the tank may swim out into the reservoir when we work on other fish. Also in the video, we have two reservoirs instead of one. This is because we didn’t consider the water recycling problem at the beginning. We added in another reservoir to hold the recycling water and the water pump. In future designs, we think using a particularly designed reservoir can solve the both problems. The reservoir has two L shaped boards on the bottom. To put a fish into the tank, we incline the tank (as shown in the figure) and the fish can go in through the gap between the boards. Then we put the tank back to level position and work on other fish. After all fish are put in, we lift the tank out of the reservoir. Here, note that the boards do not have to be fixed on the bottom plane. Removing the boards before lifting the tank may make the process easier.
The following video shows a sample result captured by the system. Sample Video
Sample Video Frame
The following image shows a single frame from the sample video.