Log evaluation using cylindrical projections
First Claim
1. A defect structure for a log, comprising:
- a two-dimensional array of data values, the data values corresponding to respective values of a first coordinate Z indicating distance along the log and a second coordinate θ
indicating an angle around the log, wherein each data value indicates a property of the log that is evaluated along a ray that originates at a center point corresponding to the value of the first coordinate Z for the data value and extends in a direction corresponding to the value of the second coordinate θ
for the data value.
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Accused Products
Abstract
A three-dimensional density distribution of a log is reduced to a two-dimensional structure that provides a convenient image or visualization of defects like knots or voids in a log, to facilitate grading and/or optimization of a sawing strategy for the log. The two-dimensional data structure is based on cylindrical or modified cylindrical coordinates Z and θ. To provide a more compact identification of defects, modified cylindrical coordinates use a Z-axis that follows the growth center in the log and determines data points by evaluating properties of the log along rays at an upward angle corresponding to limbs in a tree. A process for identifying the growth center at any distance Z along the length of the log examines or accumulates the gradient of density along lines through a cross-section of the log. Manual grading and sawing optimization can employ viewing of an image based on the two-dimensional data structure with superimposed marks indicating the boundaries of faces cut from the log. Automated grading and sawing optimization employs the two-dimensional data structure to reduce processing time when compared to processes that manipulate three-dimensional data structures.
50 Citations
32 Claims
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1. A defect structure for a log, comprising:
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a two-dimensional array of data values, the data values corresponding to respective values of a first coordinate Z indicating distance along the log and a second coordinate θ
indicating an angle around the log, whereineach data value indicates a property of the log that is evaluated along a ray that originates at a center point corresponding to the value of the first coordinate Z for the data value and extends in a direction corresponding to the value of the second coordinate θ
for the data value.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for generating a description of a log, comprising:
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for a set of locations along the length of the log, finding at each location a center point of the log;
for a set of rays that extend from the center points, evaluating a property of the log along each ray to generate a data value corresponding to a value of a first coordinate Z identifying the location for the ray and a value of a second coordinate θ
identifying a direction of the ray; and
constructing a two-dimensional data structure that describes the log, the two dimensional data structure including the data values at positions in the two-dimensional data structure according to the respective values of the first and second coordinates. - View Dependent Claims (12, 13, 14)
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15. A system for evaluating a log, comprising a program code that is computer executable for manipulating a data structure for the log, wherein the data structure comprises:
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a two-dimensional array of data values, the data values corresponding to respective values of a first coordinate Z indicating distance along the log and a second coordinate θ
indicating an angle around the log, whereineach data value indicates a property of the log that is evaluated along a ray that originates at a center point corresponding to the value of the first coordinate Z for the data value and extends in a direction corresponding to the value of the second coordinate θ
for the data value.- View Dependent Claims (16, 17, 18, 19)
a display device; and
a processor capable of executing the program code, wherein in executing the program code the processor controls display of an image on the display device, the image including pixels that correspond to the data values of the data structure and have shades defined by the respective data values.
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17. The system of claim 16, wherein executing the program code further superimposes marks in the image, the marks indicating boundaries of one or more faces of the log that results when sawing the log.
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18. The system of claim 17, wherein executing the program code further permits user controlled shifting of the marks relative to the image.
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19. The system of claim 15, wherein the program code manipulates the data structure to generate a grade value for the log.
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20. A method for grading a log, comprising:
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determining a computer tomography (CT) data structure representing the log; and
processing the CT data structure to arrive at a grade for the log, wherein processing the CT data comprises;
creating a two-dimensional array of data values indicating a defect structure of the log, each data value indicating presence or absence of a defect in a portion of the log corresponding to the data value, wherein each data value in the two dimensional array corresponds to values of a first coordinate Z indicating a position along the length of the log and a second coordinate θ
indicating an angle around the log;
evaluating the two-dimensional array to determine sizes of blocks in the two-dimensional array, that are free of data values indicating defects; and
assigning the grade to the log according to the sizes. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
creating an image having pixels that correspond to the data values and have shades according to the data values; and
viewing of the image by a grader, wherein the grader recognizes the sizes of the blocks through evaluating areas of the image having a shade indicating an absence of defects.
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22. The method of claim 21, wherein the grader assigns the grade to the log qualitatively based on the viewing of the image.
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23. The method of claim 21, further comprising superimposing on the image, marks indicating boundaries of one or more faces of the log that results from a sawing strategy for the log.
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24. The method of claim 23, further comprising shifting the image relative to the marks to minimizes defects within the boundaries of the one or more faces.
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25. The method of claim 24, further comprising selecting an orientation of the log according to positions of the marks that minimize defects within the boundaries of the one or more faces.
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26. The method of claim 20, wherein evaluating the two-dimensional array comprises executing a computer program that manipulates the two-dimensional array.
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27. The method of claim 26, wherein executing the computer program comprises:
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(a) determining a number N of data values that are consecutive in a direction of the second coordinate θ and
correspond to a desired width of defect-free wood;
(b) scanning the two-dimensional array in the direction of the second coordinate until identifying N consecutive data values that indicate absence of a defect;
(c) scanning the two-dimensional array in a direction of the first coordinate to determine a size of a block that is defect free;
(d) increasing the grade value for the log by an amount corresponding to the size of the block that is defect-free;
(e) repeating steps b, c, and d to account for defect-free blocks in the two-dimensional data structure.
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28. A method for grading a log comprising:
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(a) creating a two-dimensional array of data values indicating a defect structure of the log, each data value indicating presence or absence of a defect in a portion of the log corresponding to the data value, wherein data values in the two dimensional array correspond to values of a fist coordinate Z indicating a position along the length of the log and a second coordinate θ
indicating an angle around the log;
(b) selecting a sawing strategy for the log;
(c) selecting an orientation of the log for the sawing strategy;
(d) identifying a sub-array of the two-dimensional array, the sub-array corresponding to a face of the log resulting from the sawing strategy and the orientation;
(e) evaluating the sub-array to determine sizes of blocks in the sub-array, that are free of data values indicating defects; and
(f) assigning a first grade value to the face according to the sizes;
(g) repeating steps (d), (e), and (f) for one or more faces of the log resulting from the sawing strategy and the orientation;
(h) combining the first grade values of the faces to generate a second grade value for the orientation; and
(i) repeating steps (c) to (h) for one or more additional orientations of the log;
(j) assigning a third grade value to the log based on a best of the second grade values.
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29. A method for identifying a growth center of a log, comprising:
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for each line in a first set of lines through a cross-section of the log, determining an accumulated absolute value of a gradient of density of the log along the line;
identifying a first line that is in the first set and has an accumulated absolute value as large as any determined for lines in the first set;
for each line in a second set of lines through the cross-section of the log, determining an accumulated absolute value of a gradient of density of the log along the line;
identifying a second line that is in the second set and has an accumulated absolute value as large as any determined for lines in the second set; and
identifying the growth center as being at an intersection of the first line and the second line. - View Dependent Claims (30, 31, 32)
determining a geometric center of the log; and
selecting a central area that is smaller than the cross-section of the log and contains the geometric center of the log, wherein each line in the first and second sets passes through the central area.
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32. The method of claim 31, wherein determining the accumulated absolute values of the gradient of the density of the log only considers densities for points inside the central area.
Specification