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A Digital Image Processing System to
Characterize Frazil Ice

Mike Morris

Frazil ice has a significant economical and social impact in northern regions around the world. The ability to predict the evolution and behavior of frazil ice based on environmental conditions, such as air temperature and water velocity, is an important step in minimizing its impacts on society. One method of advancing our understanding is through frazil ice research. An important aspect of frazil ice research is the ability to accurately detect and measure frazil ice. A number of instruments have been developed that can indirectly measure frazil ice concentration using electrical conductivity, laser Doppler velocimetry, acoustics, calorimetry, or time-domain reflectometry. Although frazil ice concentration is an important characteristic, a more detailed feature necessary for the advancement of frazil ice research is the particle size distribution. Photography is an excellent method of obtaining this information. Successful attempts have been made at using photography to capture images of frazil ice in the laboratory, but due to the labour intensiveness manual analysis, only a limited number of images could be captured and analyzed. In an attempt to improve the speed of image analysis and collect larger quantities of data, a digital image processing system was developed.

Frazil ice particles were produced in a counter-rotating flume housed in a large cold-room. Digital images of frazil ice were recorded under a cross-polarized light technique allowing the normally transparent ice crystals to be clearly distinguishable. A digital image processing system was developed to digitally manipulate and systematically analyze the images to extract the number, size, and location in the water column of every ice particle. This data could then be analyzed to reveal the temporal and spatial variation of frazil ice.

After the digital image processing algorithms were developed, a series of experiments were conducted and analyzed to test and validate the frazil ice generation and image processing procedures. The results indicated that the production and analysis of frazil ice particles were very reproducible. The results of the experiments were also compared to reveal the effects of air temperature and water velocity on the evolution of frazil ice.

Click Images To Enlarge

Counter Rotating Flume

Cameras Used to Capture Frazil Ice Images

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