Method and apparatus for counting underwater objects using an ultrasonic wave

A fish counting method for counting a number of fish by emitting an ultrasonic wave to a predetermined area where fish pass in a body of water and receiving reflected waves from fish bodies,

• wherein, an ultrasonic wave fish shade image is produced for showing changes of fish shades as a pixel signal by periodically storing said reflected waves received from a cross section of said predetermined area,
• an area of a group of crowded pixels in said ultrasonic wave fish shade image is calculated, and when said calculated area is not larger than a predetermined area an image processing in a fish shade unit is carried out to said group of pixels of said ultrasonic wave fish shade based on a fish shade decision rule and the number of fish is counted, and
• when said calculated area exceeds said predetermined area, a shape estimation is carried out on the basis of the calculation of a feature including number of holes in a group of said pixels in such a manner that when the number of holes is smaller than a predetermined value, it is estimated as a large-type image of one fish and when the number of holes is larger than the predetermined value, it is estimated as a small-type fish crowded image, relational data between an area value of a group of pixels and a number of fish stored in advance based on past actual data is referred to and the number of fish corresponding to said area value of said corresponding group of pixels is estimated.

A fish counting method for counting a number of fish by emitting an ultrasonic wave to a predetermined area where fish pass in a body of water and receiving reflected waves from fish bodies,

• wherein, an ultrasonic wave fish image for showing changes of fish shades is produced by periodically storing said reflected waves received from a part of area of a cross section of said predetermined area, said image showing a presence or absence of said reflected wave by a presence or absence of a pixel signal, an image processing in a fish shade unit is carried out to said ultrasonic wave fish shade image based on a fish shade decision rule in which adjacent pixel signals are merged into the same fish shade if a distance between adjacent pixel signals is not larger than a predetermined distance, and adjacent pixel signals are separated from each other as different fish shades when a distance between adjacent pixel signals is larger than said predetermined distance, and the number of fish and a fish density distribution of fish passing said part area of said cross section of said fish pass during a predetermined period is counted based on said fish shade decision rule utilizing the merging and separating processes effected in accordance with the distance between adjacent pixel images, and
• a fish density distribution of a whole area of said fish pass cross section stored in advance based on past actual data and said counted number of fish are referred to, and the number of fish of a whole area of a fish pass corresponding to said counted number of fish is estimated from a correlation between said part area fish density distribution and said whole area fish density distribution.

A fish counter for counting a number of fish by emitting an ultrasonic wave to a predetermined area where fish pass in a body of water and receiving reflected waves from fish bodies, comprising:

• an ultrasonic wave sensor installed in a depth direction or a width direction of a cross section of said fish pass, having at least one oscillator laid out for transmitting an ultrasonic wave and receiving reflected waves,
• ultrasonic wave image producing means for periodically storing reflected waves from said ultrasonic wave sensor based on a pixel signal corresponding to said depth direction or said width direction and for producing an ultrasonic wave fish shade image for showing a fish shade and changes of said fish shade,
• fish shade count image producing means for taking in one scene for counting from said ultrasonic wave fish shade image, producing a fish shade count image of said scene by carrying out an image processing for discriminating the image for each fish shade unit and counting the number of fish according to this image,
• fish shade decision rule storing means that merges adjacent pixel images into the same fish shade when a distance between adjacent left and right and/or up and down pixel signals is not larger than a predetermined distance in said one scene, separates said adjacent pixel images from each other as different fish shades when a distance between said adjacent left and right and/or up and down pixel signals is larger than said predetermined distance, and erases said adjacent pixels when said pixel signal is a noise pattern, and carries out an image processing in said fish shade unit by referring to said decision rule in which said predetermined distance has been set, and
• output means for statistically processing the number of fish counted by said fish shade count image producing means and outputting a result.

A fish counter for counting a number of fish by emitting an ultrasonic wave to a predetermined area where fish pass in a body of water and receiving reflected waves from fish bodies, comprising:

• an ultrasonic wave sensor installed in a water depth direction of said predetermined area, having a plurality of oscillators laid out for transmitting an ultrasonic wave and receiving reflected waves,
• ultrasonic wave image producing means for periodically storing reflected waves from said ultrasonic wave sensor based on a pixel signal corresponding to said depth direction and producing an ultrasonic wave fish shade image for showing a fish shade and changes of said fish shade passing a detecting area of said sensor at a cross section of said predetermined area,
• fish shade count image producing means for carrying out a processing of taking in one scene for counting fish from said ultrasonic wave fish shade image, producing a fish shade count image of said scene by carrying out an image processing in fish shade unit, and counting fish in said sensor detecting area, and
• fish number correcting means for storing a fish number correction coefficient of said sensor detecting area to be determined by a relation between a whole-area fish density distribution of said cross section of said predetermined area and number of fish stored in advance based on past actual data and said whole area of said predetermined area, correcting a counted fish number in said sensor detecting area by said correction coefficient, and estimating the fish number in said whole area of said predetermined area.