Sonar rendering systems and associated methods

• US 9,182,486 B2
• Filed: 12/07/2011
• Issued: 11/10/2015
• Est. Priority Date: 12/07/2011
• Status: Active Grant

• Current Assignee: Navico Incorporated (Brunswick Corporation)
• Original Assignee: Navico Holding A.S. (Brunswick Corporation)
• Inventors: Brown, Kevin, Coleman, Aaron
• Primary Examiner(s): Alsomiri, Isam
• Assistant Examiner(s): Baghdasaryan, Hovhannes
• Application Number:
  US13/313,574
• Publication Number:
  US 20130148471A1
• Time in Patent Office: 1,434 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 15/50 Systems of measurement, based on relative movement of the target
• CPC Class Codes: G01S 15/86 Combinations of sonar systems with lidar systems; Combinations of sonar systems with systems not using wave reflection
• CPC Class Codes: G01S 15/8902 Side-looking sonar
• CPC Class Codes: G01S 7/6281 Composite displays, e.g. split-screen, multiple images
• CPC Class Codes: G01S 7/629 the display being oriented or displaced in accordance with the movement of object carrying the transmitting and receiving apparatus

Abstract

Sonar rendering systems and methods are described herein. One example is an apparatus that includes a transducer element, position sensing circuitry, processing circuitry, and a display device. The processing circuitry may be configured to receive raw sonar data and positioning data, convert the raw sonar data into range cell data based at least on amplitudes of the return echoes, make a location-based association between the raw sonar data and the positioning data, plot the range cell data based on respective positions derived from the positioning data and rotate the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data. The processing circuitry may be further configured to convert the adjusted range cell data into sonar image data, and cause the display device to render the sonar image data with a presentation of a geographic map.

Claims

1. An apparatus comprising:

a transducer assembly configured to emit a sonar beam, receive return echoes of the sonar beam, and convert the return echoes into raw sonar data, wherein the transducer assembly is configured to be affixed to a watercraft;

position sensing circuitry configured to determine positioning data, the positioning data being indicative of a position of the watercraft;

processing circuitry configured to;

receive the raw sonar data and the positioning data,

convert the raw sonar data into range cell data based at least on amplitudes of the return echoes;

make a location-based association between the range cell data and the positioning data,

plot the range cell data based on respective positions derived from the positioning data and rotate the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data, and

convert the adjusted range cell data into sonar image data; and

a display device configured to render at least a portion of a sonar image over a geographic map at a position and oriented in the direction of movement of the watercraft, wherein the sonar image is based on the sonar image data, wherein the position of the sonar image on the geographic map corresponds to the position of the watercraft associated with the sonar image data;

wherein, in an instance in which at least two sets of range cell data are associated with a same location, the display device is configured to render the portion of the sonar image at the same location corresponding to one of the at least two sets of range cell data, wherein each set of range cell data of the at least two sets of range cell data comprises an amplitude value at the same location, and wherein the amplitude value for the one of the at least two sets of range cell data that corresponds to the rendered portion of the sonar image is larger than any of the other amplitude values of the other sets of range cell data of the at least two sets of range cell data.

2. The apparatus of claim 1, wherein the transducer assembly includes a rectangular transducer configured to emit a fan-shaped sonar beam, and wherein the transducer assembly is further configured to be positioned on the watercraft to operate as a side scan sonar transducer assembly.

3. The apparatus of claim 1, wherein the display device is configured to render the sonar image as one of a plurality of selectable layers.

4. The apparatus of claim 1, wherein when the watercraft turns, the processing circuitry is configured to spread the range cell data on the outside of the turn.

5. The apparatus of claim 3, wherein the plurality of selectable layers includes a weather layer, a radar layer, or a depth sounding layer.

6. The apparatus of claim 1, wherein the display device is configured to render the sonar image as a semi-transparent layer.

7. The apparatus of claim 1, wherein the transducer assembly is configured to repeatedly emit the sonar beam at a scan rate to generate, and upon generation transmit to the processing circuitry, incremental sets of raw sonar data including a given incremental set of the raw sonar data;

wherein the processing circuitry is configured to, in response to receiving the given incremental set of raw sonar data, process the incremental set of raw sonar data to generate a sonar column of range cell data, and generate a given incremental set of sonar image data based on the sonar column of range cell data; and

wherein the display device is configured to, in response to the generation of the given incremental set of sonar image data, render the sonar image based on the given incremental set of sonar image data.

8. The apparatus of claim 7, wherein the processing circuitry is configured to scale the sonar column of range cell data based on a zoom level of the geographic map.

9. The apparatus of claim 7 wherein the processing circuitry is configured to orient the sonar column of range cell data relative to a coordinate system of the geographic map.

10. The apparatus of claim 7 wherein the display device is configured to render the sonar image at the position on the geographic map that is associated with an area that the transducer assembly captured the return echoes of the sonar beam.

11. The apparatus of claim 7, wherein the position sensing circuitry comprises a global positioning system (GPS) device and wherein the position sensing circuitry is configured to determine the positioning data of the watercraft as GPS coordinates;

and wherein processing circuitry is configured to plot and rotate the sonar column of range cell data using the GPS coordinates.

12. The apparatus of claim 7, wherein the processing circuitry is configured to generate a respective sonar column of range cell data for each incremental set of raw sonar data;

and wherein the display device is configured to render the sonar image based on the sonar columns of range cell data.

13. The apparatus of claim 7 wherein the processing circuitry is configured to discontinue rendering an oldest sonar image upon rendering the sonar image.

14. The apparatus of claim 7, wherein the transducer assembly includes a rectangular transducer element configured to emit a fan-shaped sonar beam and configured to be positioned on the watercraft to operate as a side scan sonar transducer assembly;

and wherein the processing circuitry is configured to rotate the sonar column of range cell data based on the direction of movement of the watercraft such that the sonar image is rotated to extend in a direction that is substantially perpendicular to the direction of movement of the watercraft.

15. The apparatus of claim 7, wherein the processing circuitry is configured to determine a horizontal extent of the sonar column of range cell data, and wherein the display device configured to render a visual indicator of a position indicating the horizontal extent of the sonar column of range cell data.

16. The apparatus of claim 15, wherein the display device is configured to render the visual indicator without also presenting information representative of the echo returns.

17. The apparatus of claim 15 further comprising a data storage device and wherein the processing circuitry is configured to store the sonar column of range cell data in the data storage device.

18. The apparatus of claim 7, wherein the processing circuitry is configured to determine a horizontal extent of the sonar column of range cell data based on the positioning data generated by the position sensing circuitry.

19. The apparatus of claim 1, wherein the processing circuitry is configured to analyze the range cell data to identify a water column portion of the range cell data, wherein the water column portion of the range cell data is a portion of the range cell data describing the echo returns from the transducer assembly to the seafloor based on an angle of the sonar beam;

and wherein the processing circuitry is configured to remove the range cell data in the water column portion.

20. The apparatus of claim 19, wherein the processing circuitry configured to analyze the range cell data to identify the water column portion includes being configured to identify the water column portion of the range cell data based on a quantity of echo returns in a given area exceeding a relative threshold.

21. The apparatus of claim 19, wherein the processing circuitry is configured to determine seafloor depth data, and wherein the processing circuitry configured to analyze the range cell data to identify the water column portion includes being configured to identify the water column portion of the range cell data based on the seafloor depth data.

22. The apparatus of claim 1, wherein the processing circuitry is configured to analyze the range cell data to identify a water column portion of the range cell data and a seafloor surface portion of the range cell data, wherein the water column portion of the range cell data is a portion of the range cell data describing the echo returns from a volume extending from the transducer assembly to the seafloor based on an angle of the sonar beam, and wherein the seafloor surface portion is a portion of the range cell data describing the echo returns that interact with the seafloor;

and wherein the processing circuitry is further configured to remove the range cell data in the water column portion and expand the range cell data of the seafloor surface portion to maintain a width of the range cell data despite the omission of the water column portion.

23. The apparatus of claim 1 further comprising a memory device, and wherein the processing circuitry is configured to store the range cell data as a sonar log file in the memory device.

24. The apparatus of claim 23, wherein the processing circuitry configured to plot, and rotate the range cell data is configured to plot and rotate the range cell data in the sonar log file.

25. The apparatus of claim 24, wherein the processing circuitry configured to convert the adjusted range cell data includes being configured to:

determine a geographic area covered by the adjusted range cell data;

based on the geographic area, apply a first grid system to the adjusted range cell data to group the adjusted range cell data into one or more tiles; and

separately store the groups of adjusted range cell data within respective tiles of the one or more tiles.

26. The apparatus of claim 25, wherein the processing circuitry configured to separately store the groups of adjusted range cell data within the respective tiles includes being configured to separately store the groups of adjusted range cell data at a first resolution within the respective tiles as one resolution layer of a data structure comprising a plurality of resolution layers.

27. The apparatus of claim 26, wherein the processing circuitry is configured to apply a second grid system to the adjusted range cell data at a second resolution.

28. The apparatus of claim 27, wherein the processing circuitry is configured to generate a node tree indicative of an architecture of the resolution layers and tiles of the data structure.

29. The apparatus of claim 26, wherein the sonar image data is the derived from range cell data of a tile associated with one of the plurality of resolution layers of the data structure.

30. The apparatus of claim 26, wherein the processing circuitry is configured to select one of the plurality of resolution layers based on a resolution of the geographic map.

31. The apparatus of claim 26, wherein the processing circuitry is configured to select one of the plurality of resolution layers based on a resolution of the presentation of the geographic map and a node tree indicative of an architecture of the resolution layers and tiles of the data structure.

32. The apparatus of claim 26, wherein the processing circuitry is configured to scale and orient the range cell data of a given tile based on an orientation and zoom level of the geographic map, and color the range cell data of the given tile by applying a color palette to the range cell data of the given tile;

and

wherein the sonar image data is derived from the range cell data of the given tile that has been oriented, scaled, and colored.

33. The apparatus of claim 12, wherein the processing circuitry configured to color the range cell data of the given tile includes being configured to color the range cell data of the given tile to impart information indicating a density of echo returns at a location of the range cell data of the given tile.

34. The apparatus of claim 25, wherein the processing circuitry configured to apply the first grid system to the adjusted range cell data to group the adjusted range cell data into tiles includes being configured to define each tile based on characteristics including a tile center point, and a tile width.

35. The apparatus of claim 1, wherein the processing circuitry is configured to receive depth sounding data and associate the depth sounding data with a location based on the positioning data;

and wherein the display device is configured to render indications of the depth sounding data with the sonar image.

36. The apparatus of claim 7, wherein the processing circuitry is configured to dynamically adjust the scan rate based on a speed of the watercraft such that the transducer assembly is configured to repeatedly emit the sonar beam at a first scan rate when the watercraft is traveling at a first speed and a second scan rate when the watercraft is traveling at a second speed, wherein the first scan rate is greater than the second scan rate and the first speed is greater than the second speed.

37. A method comprising:

emitting a sonar beam by a transducer assembly affixed to a watercraft;

receiving return echoes of the sonar beam;

converting the return echoes into raw sonar data;

determining positioning data by position sensing circuitry, the positioning data being indicative of a position of the watercraft;

receiving the raw sonar data and the positioning data by processing circuitry;

converting the raw sonar data into range cell data based at least on amplitudes of the return echoes;

making a location-based association between the range cell data and the positioning data;

plotting the range cell data based on respective positions derived from the positioning data and rotating the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data;

converting the adjusted range cell data into sonar image data; and

rendering, by a display device, at least a portion of a sonar image over a geographic map at a position and oriented in the direction of movement of the watercraft, wherein the sonar image is based on the sonar image data, wherein the position of the sonar image on the geographic map corresponds to the position of the watercraft associated with the sonar image data;

wherein, in an instance in which at least two sets of range cell data are associated with a same location, the display device is configured to render the portion of the sonar image at the same location corresponding to one of the at least two sets of range cell data, wherein each set of range cell data of the at least two sets of range cell data comprises an amplitude value at the same location, and wherein the amplitude value for the one of the at least two sets of range cell data that corresponds to the rendered portion of the sonar image is larger than any of the other amplitude values of the other sets of range cell data of the at least two sets of range cell data.

38. The method of claim 37, wherein emitting the sonar beam includes emitting a fan-shaped sonar beam, wherein the transducer assembly is configured to be positioned on the watercraft to operate as a side scan sonar transducer assembly.

39. The method of claim 37, wherein rendering the sonar image includes rendering the sonar image as one of a plurality of selectable layers.

40. The method of claim 37, wherein the method further comprises spreading the range cell data on the outside of a turn when the watercraft turns.

41. The method of claim 39, wherein the plurality of selectable layers includes a weather layer, a radar layer, or a depth sounding layer.

42. The method of claim 37, wherein rendering the sonar image includes rendering the sonar image as a semi-transparent layer.

43. The method of claim 37, wherein emitting the sonar beam includes repeatedly emitting the sonar beam at a scan rate to generate, and upon generation transmit to the processing circuitry, incremental sets of raw sonar data including a given incremental set of the raw sonar data;

wherein the method further comprises, in response to receiving the given incremental set of raw sonar data, processing the incremental set of raw sonar data to generate a sonar column of range cell data, and generating a given incremental set of sonar image data based on the sonar column of range cell data; and

wherein the method further comprises, in response to the generation of the given incremental set of sonar image data, rendering the sonar image based on the given incremental set of sonar image data.

44. The method of claim 43 further comprising scaling the sonar column of range cell data based on a zoom level of the geographic map.

45. The method of claim 43 further comprising orienting the sonar column of range cell data relative to a coordinate system of the geographic map.

46. The method of claim 43, wherein rendering the sonar image includes rendering the sonar image at the position on the geographic map that is associated with an area that the transducer assembly captured the return echoes of the sonar beam.

47. The method of claim 43, wherein determining the positioning data includes determining the positioning data of the watercraft as GPS coordinates;

and wherein plotting and rotating the range cell data is performed using the GPS coordinates.

48. The method of claim 43 further comprising:

generating a respective sonar column of range cell data for each incremental set of raw sonar data; and

rendering the sonar image based on the sonar columns of range cell data.

49. The method of claim 43 further comprising discontinuing the rendering of an oldest sonar image upon rendering the sonar image.

50. The method of claim 43, wherein the transducer assembly is configured to be positioned on the watercraft to operate as a side scan sonar transducer assembly;

and wherein the method further comprises rotating the sonar column of range cell data based on the direction of movement of the watercraft such that the sonar image is rotated to extend in a direction that is substantially perpendicular to the direction of movement of the watercraft.

51. The method of claim 43 further comprising determining a horizontal extent of the sonar column of range cell data, and wherein rendering the sonar image includes rendering a visual indicator of a position indicating the horizontal extent of the sonar column of range cell data.

52. The method of claim 51, wherein rendering the visual indicator includes rendering the visual indicator without also presenting information representative of the echo returns.

53. The method of claim 51 further comprising storing the sonar column of range cell data in a data storage device.

54. The method of claim 51 further comprising determining a horizontal extent of the sonar column of range cell data based on the positioning data.

55. The method of claim 37 further comprising analyzing the range cell data to identify a water column portion of the range cell data, wherein the water column portion of the range cell data is a portion of the range cell data describing the echo returns from a volume extending from the transducer assembly to the seafloor based on an angle of the sonar beam;

and removing the range cell data in the water column portion.

56. The method of claim 55, wherein analyzing the range cell data to identify the water column portion includes identifying the water column portion of the range cell data based on a quantity of echo returns in a given area exceeding a relative threshold.

57. The method of claim 55 further comprising determining seafloor depth data, and wherein analyzing the range cell data to identify the water column portion includes identifying the water column portion of the range cell data based on the seafloor depth data.

58. The method of claim 37 further comprising analyzing the range cell data to identify a water column portion of the range cell data and a seafloor surface portion of the range cell data, wherein the water column portion of the range cell data is a portion of the range cell data describing the echo returns from a volume extending from the transducer assembly to the seafloor based on an angle of the sonar beam, and wherein the seafloor surface portion is a portion of the range cell data describing the echo returns that interact with the seafloor;

and

wherein the method further comprises removing the range cell data in the water column portion and expanding the range cell data of the seafloor surface portion to maintain a width of the range cell data despite the omission of the water column portion.

59. The method of claim 37 further comprising storing the range cell data as a sonar log file in a data storage device.

60. The method of claim 59, wherein plotting and rotating the range cell data includes plotting and rotating the range cell data in the sonar log file.

61. The method of claim 60, wherein converting the adjusted range cell data includes:

determining a geographic area covered by the adjusted range cell data;

based on the geographic area, applying a first grid system to the adjusted range cell data to group the adjusted range cell data into one or more tiles; and

separately storing the groups of adjusted range cell data within respective tiles of the one or more tiles.

62. The method of claim 61, wherein separately storing the groups of adjusted range cell data within the respective tiles includes separately storing the groups of adjusted range cell data at a first resolution within the respective tiles as one resolution layer of a data structure comprising a plurality of resolution layers.

63. The method of claim 62 further comprising applying a second grid system to the adjusted range cell data at a second resolution.

64. The method of claim 63 further comprising generating a node tree indicative of an architecture of the resolution layers and tiles of the data structure.

65. The method of claim 62, wherein the sonar image data is the derived from range cell data of a tile associated with one of the plurality of resolution layers of the data structure.

66. The method of claim 62 further comprising selecting one of the plurality of resolution layers based on a resolution of the geographic map.

67. The method of claim 62 further comprising selecting one of the plurality of resolution layers based on a resolution of the presentation of the geographic map and a node tree indicative of an architecture of the resolution layers and tiles of the data structure.

68. The method of claim 62 further comprising:

scaling and orienting the range cell data of a given tile based on an orientation and zoom level of the presentation of the geographic map;

coloring the range cell data of the given tile by applying a color palette to the range cell data of the given tile; and

wherein the sonar image data is derived from the range cell data of the given tile that has been oriented, scaled, and colored.

69. The method of claim 68, wherein coloring the range cell data of the given tile includes coloring the range cell data of the given tile to impart information indicating a density of echo returns at a location of the range cell data of the given tile.

70. The method of claim 61, wherein applying the first grid system to the adjusted range cell data to group the adjusted range cell data into tiles includes defining each tile based on characteristics including a tile center point, and a tile width.

71. The method of claim 37 further comprising:

receiving depth sounding data;

associating the depth sounding data with a location based on the positioning data; and

rendering indications of the depth sounding data with the sonar imaging data.

72. The method of claim 43 further comprising dynamically adjusting the scan rate based on a speed of the watercraft such that the transducer assembly is configured to repeatedly emit the sonar beam at a first scan rate when the watercraft is traveling at a first speed and a second scan rate when the watercraft is traveling at a second speed, wherein the first scan rate is greater than the second scan rate and the first speed is greater than the second speed.

73. A non-transitory computer-readable medium comprised of at least one memory device having computer program instructions stored thereon, the computer program instructions being configured, when executed by processing circuitry, to:

cause transmission of a sonar beam via a transducer assembly affixed to a watercraft;

determine positioning data by position sensing circuitry, the positioning data being indicative of a position of the watercraft;

convert received raw sonar data into range cell data based at least on amplitudes of return echoes of the sonar beam received by the transducer assembly, wherein the raw sonar data is based on the return echoes;

make a location-based association between the range cell data and the positioning data;

plot the range cell data based on respective positions derived from the positioning data and rotate the range cell data based on a direction of movement of the watercraft to generate adjusted range cell data;

convert the adjusted range cell data into sonar image data; and

render at least a portion of a sonar image over a geographic map at a position and oriented in the direction of movement of the watercraft, wherein the sonar image is based on the sonar image data, wherein the position of the sonar image on the geographic map corresponds to the position of the watercraft associated with the sonar image data;

wherein, in an instance in which at least two sets of range cell data are associated with a same location, the portion of the sonar image that is rendered at the same location corresponds to one of the at least two sets of range cell data, wherein each set of range cell data of the at least two sets of range cell data comprises an amplitude value at the same location, and wherein the amplitude value for the one of the at least two sets of range cell data that corresponds to the rendered portion of the sonar image is larger than any of the other amplitude values of the other sets of range cell data of the at least two sets of range cell data.

74. The computer-readable medium of claim 73, wherein the computer program instructions are configured to cause transmission of a rectangular sonar beam, wherein the transducer assembly is a member of a transducer array and the transducer assembly is configured to be positioned on the watercraft to operate as a side scan sonar transducer assembly.

75. The computer-readable medium of claim 73, wherein the computer program instructions are configured to render the sonar image as one of a plurality of selectable layers over the geographic map.

76. The computer program product of claim 73, wherein the computer program instructions are configured to spread the range cell data on the outside of a turn when the watercraft turns.

77. The computer-readable medium of claim 75, wherein the plurality of selectable layers includes a weather layer, a radar layer, or a depth sounding layer.

78. The computer-readable medium of claim 73, wherein the computer program instructions are configured to render the sonar image as a semi-transparent layer over the geographic map.

79. The computer-readable medium of claim 73, wherein the computer program instructions are configured to cause repeated transmission of the sonar beam at a scan rate to generate, and upon generation transmit to the processing circuitry, incremental sets of raw sonar data including a given incremental set of the raw sonar data;

wherein the computer program instructions are further configured to, in response to receiving the given incremental set of raw sonar data, process the incremental set of raw sonar data to generate a sonar column of range cell data, and generate a given incremental set of sonar image data based on the sonar column of range cell data; and

wherein the computer program instructions are further configured to, in response to the generation of the given incremental set of sonar image data, render the sonar image based on the given incremental set of sonar image data.

80. The computer-readable medium of claim 79, wherein the computer program instructions are further configured to scale the sonar column of range cell data based on a zoom level of the geographic map.

81. The computer-readable medium of claim 79, wherein the computer program instructions are further configured to orient the sonar column of range cell data relative to a coordinate system of the geographic map.

82. The computer-readable medium of claim 79, wherein the computer program instructions are configured to render the sonar image at the position on the geographic map that is associated with an area that the transducer assembly captured the return echoes of the sonar beam.

83. The computer-readable medium of claim 79, wherein the computer program instructions are configured to determine the positioning data of the watercraft as GPS coordinates;

and wherein the computer program instructions are configured to plot and rotate the range cell data using the GPS coordinates.

84. The computer-readable medium of claim 79, wherein the computer program instructions are further configured to:

generate a respective sonar column of range cell data for each incremental set of raw sonar data; and

render the sonar image based on the sonar columns of range cell data.

85. The computer-readable medium of claim 79, wherein the computer program instructions are further configured to discontinue rendering an oldest sonar image upon rendering the sonar image.

86. The computer-readable medium of claim 79, wherein the computer program instructions are further configured to rotate the sonar column of range cell data based on the direction of movement of the watercraft such that the sonar image is rotated to extend in a direction that is substantially perpendicular to the direction of movement of the watercraft, wherein the transducer assembly is configured to be positioned on the watercraft to operate as a side scan sonar transducer assembly.

87. The computer-readable medium of claim 79, wherein the computer program instructions are further configured to determine a horizontal extent of the sonar column of range cell data, and wherein the computer program instructions configured to render the sonar image by rendering a visual indicator of a position indicating the horizontal extent of the sonar column of range cell data.

88. The computer-readable medium of claim 87, wherein the computer program instructions are configured to render the visual indicator without also presenting information representative of the echo returns.

89. The computer-readable medium of claim 87, wherein the computer program instructions are further configured to store the sonar column of range cell data in a data storage device.

90. The computer-readable medium of claim 87, wherein the computer program instructions are further configured to determine a horizontal extent of the sonar column of range cell data based on the positioning data.

91. The computer-readable medium of claim 73, wherein the computer program instructions are further configured to:

analyze the range cell data to identify a water column portion of the range cell data, wherein the water column portion of the range cell data is a portion of the range cell data describing the echo returns from a volume extending from the transducer assembly to the seafloor based on an angle of the sonar beam; and

remove the range cell data in the water column portion.

92. The computer-readable medium of claim 91, wherein the computer program instructions are configured to identify the water column portion of the range cell data based on a quantity of echo returns in a given area exceeding a relative threshold.

93. The computer-readable medium of claim 91, wherein the computer program instructions are further configured to determine seafloor depth data, and wherein the computer program instructions configured to identify the water column portion of the range cell data based on the seafloor depth data.

94. The computer-readable medium of claim 73, wherein the computer program instructions are further configured to analyze the range cell data to identify a water column portion of the range cell data and a seafloor surface portion of the range cell data, wherein the water column portion of the range cell data is a portion of the range cell data describing the echo returns from a volume extending from the transducer assembly to the seafloor based on an angle of the sonar beam, and wherein the seafloor surface portion is a portion of the range cell data describing the echo returns that interact with the seafloor;

and

wherein the computer program instructions are further configured to remove the range cell data in the water column portion and expand the range cell data of the seafloor surface portion to maintain a width of the range cell data despite the omission of the water column portion.

95. The computer-readable medium of claim 73, wherein the computer program instructions are further configured to store the range cell data as a sonar log file in a data storage device.

96. The computer-readable medium of claim 95, wherein the computer program instructions are configured to plot and rotate the range cell data in the sonar log file.

97. The computer-readable medium of claim 96, wherein the computer program instructions are configured to convert the adjusted range cell data by:

determining a geographic area covered by the adjusted range cell data;

applying, based on the geographic area, a first grid system to the adjusted range cell data to group the adjusted range cell data into one or more tiles; and

separately storing the groups of adjusted range cell data within respective tiles of the one or more tiles.

98. The computer-readable medium of claim 97, wherein the computer program instructions are configured to separately store the groups of adjusted range cell data within the respective tiles at a first resolution within the respective tiles as one resolution layer of a data structure comprising a plurality of resolution layers.

99. The computer-readable medium of claim 97, wherein the computer program instructions are further configured to apply a second grid system to the adjusted range cell data at a second resolution.

100. The computer-readable medium of claim 99, wherein the computer program instructions are further configured to generate a node tree indicative of an architecture of the resolution layers and tiles of the data structure.

101. The computer-readable medium of claim 98, wherein the sonar image data is the derived from range cell data of a tile associated with one of the plurality of resolution layers of the data structure.

102. The computer-readable medium of claim 98, wherein the computer program instructions are further configured to select one of the plurality of resolution layers based on a resolution of the presentation of the geographic map.

103. The computer-readable medium of claim 98, wherein the computer program instructions are further configured to select one of the plurality of resolution layers based on a resolution of the presentation of the geographic map and a node tree indicative of an architecture of the resolution layers and tiles of the data structure.

104. The computer-readable medium of claim 98, wherein the computer program instructions are further configured to:

scale and orient the range cell data of a given tile based on an orientation and zoom level of the presentation of the geographic map; and

color the range cell data of the given tile by applying a color palette to the range cell data of the given tile; and

wherein the sonar image data is derived from the range cell data of the given tile that has been oriented, scaled, and colored.

105. The computer-readable medium of claim 104, wherein the computer program instructions are configured to color the range cell data of the given tile to impart information indicating a density of echo returns at a location of the range cell data of the given tile.

106. The computer-readable medium of claim 97, wherein the computer program instructions configured to define each tile based on characteristics including a tile center point, and a tile width.

107. The computer-readable medium of claim 73, wherein the computer program instructions are further configured to:

associate received depth sounding data with a location based on the positioning data; and

render indications of the depth sounding data with the sonar image.

108. The computer program product of claim 79, the computer program instructions configured to dynamically adjust the scan rate based on a speed of the watercraft such that the transducer assembly is configured to repeatedly emit the sonar beam at a first scan rate when the watercraft is traveling at a first speed and a second scan rate when the watercraft is traveling at a second speed, wherein the first scan rate is greater than the second scan rate and the first speed is greater than the second speed.