Scientists Wield Wiimote To Measure Evaporation

Consumer technology is advancing at such a rate that it is becoming increasingly common for such technology to find its way into various scientific applications. One of the more obvious examples is seen in the benefits high-performance computing has received from consumer graphics cards. We have also seen laptops used to measure earthquakes, and accelerometers such as those found in the Wiimote, iPhone, and other consumer electronics used to measure the flight patterns of the Malayan colugo.

In a recent paper in Water Resources Research, a team reports on the use of the Wiimote to measure evaporation. Natural evaporation rates are an important part of the water cycle; estimates of evaporation are required for weather forecasts, flood forecasts, and water resource planning, among other things.

One of the common means of measuring evaporation is simple enough: you set out a pan of water and measure the change in water level over time. Unfortunately, automated measurement typically requires a pressure transducer to accurately measure the water level, and those costs hundreds of dollars. The use of the Wiimote has the potential to substantially reduce the cost of measurement.

The methodology is simple enough. The Wiimote tracks the four brightest points in a near infrared image. Ordinarily, these four points will be the four Wii IR LEDs used to determine where the Wiimote is pointing. However, by affixing IR reflectors to a float in the water pan, the researchers were able to track the water level. This sounds simple enough, but these pans are often themselves floating in natural water bodies, and the combination of the two is likely to make waves.

To test the sensitivity of their technique to waves, the team used a small wave generator. A low-flow pump was used to change the water level. They found that even with substantial wave activity, they were able to measure changes in the average water level to within one millimeter.

However, they did find a slight bias in their absolute estimate of water level during wave activity. They hypothesize that this is due to a lag in the rates of rise and fall of their float that could be fixed with a modification. Using the Wiimote’s accelerometer to measure motion of the entire pan could also improve accuracy.

While I have to admit that I found this paper a bit mundane for what it was, the idea of using cheap sensors to measure environmental fields is one I find fascinating. For example, I wonder if the XBox 360’s depth-sensing Kinect camera could be used to measure particles such a large snowflakes in a wind field.

A first-order calculation suggests that its depth pixels are a few millimeters across for nearby objects, but it is not clear that the method it uses to calculate depth will work for small, fast-moving objects. Still, a $150 3D Particle Imaging Velocimeter would be a huge win. Environmental problems are prone to high time and space variability, and anything that can lower the cost of measurement has the potential to increase the number of measurements one can make.

The scientific community isn’t alone in getting excited about this tech. Its promise is also consistent with IBM’s recently-released Next 5 in 5 YouTube video: their prediction for the five innovations that will change our lives in the next five years. IBM predicts that simple sensor networks based in cell phones and laptops will be increasingly used to map environmental events. In addition, a large Department of Transportation project called IntelliDrive envisions using embedded sensors in cars to monitor environmental conditions.

Chime in below with your own ideas for scientific usage of consumer technology.

This story was written by Ethan Gutmann and originally published by Ars Technica on Dec. 28.