Displacement method of knot sizing

1. A method of estimating the displaced size of a knot in a lumber piece comprising the steps of:

a) providing a first radiation source on a first side of a flow path;

b) providing a first radiation sensor on an opposite second side of said flow path and cooperating with said first radiation source;

c) translating the lumber piece downstream along said flow path and between said first radiation source and said first radiation sensor while simultaneously irradiating the lumber piece with radiation from said first radiation source whereby said radiation is attenuated by said lumber piece;

d) collecting a set of first radiation intensity data from said first radiation sensor as the lumber piece is irradiated as it is translated between said first radiation source and said first sensor;

e) processing said set of first radiation intensity data to sum said first radiation intensity data and to provide radiation intensity profiles transversely of the flow path direction of said flow path and corresponding density profiles transversely of said flow path direction;

f) mapping said density profiles to model a first set of three dimensional density profiles of the lumber piece;

g) processing said first radiation intensity data to determine a clear wood density threshold value for the lumber piece and a maximum density value of said density profiles; and

h) computing a ratio of the summed density profile values to the summed maximum density values for said density profiles and multiplying said ratio with the transverse width of the lumber piece.

2. A method as defined in claim 1 wherein said ratio is computed according to:

ratio

=

Σ

⁢

⁢

measured

⁢

⁢

knot

⁢

⁢

density

-

Σ

⁢

⁢

measured

⁢

⁢

clear

⁢

⁢

density

Σ

⁢

⁢

max

⁢

⁢

knot

⁢

⁢

density

-

Σ

⁢

⁢

measured

⁢

⁢

clear

⁢

⁢

density

and wherein said width is a measured width.

3. A method as defined in claim 2 wherein said first radiation sensor comprises a plurality of radiation sensors.

4. A computer program product for use with a device having a first radiation source on a first side of a flow path and a first radiation sensor on an opposite second side of said flow path and cooperating with said first radiation source wherein a lumber piece translates downstream along said flow path and between said first radiation source and said first radiation sensor while said device simultaneously irradiates the lumber piece with radiation from said first radiation source whereby said radiation is attenuated by said lumber piece,

said computer program product comprising:

a) a computer usable medium having computer readable program code means embodied in said medium for causing the sensing of a lumber piece using said first radiation sensor to detect the attenuated radiation and thereby to collect information about the lumber piece;

b) computer readable program code means for causing the collection of a set of first radiation intensity data from said first radiation sensor as the lumber piece is irradiated as it is translated between said first radiation source and said first sensor;

c) computer readable program code means for causing the processing of said set of first radiation intensity data to sum said first radiation intensity data and to provide radiation intensity profiles transversely of the flow path direction of said flow path and corresponding density profiles transversely of said flow path direction;

d) computer readable program code means for causing the mapping of said density profiles to model a first set of three dimensional density profiles of the lumber piece;

e) computer readable program code means for causing the processing of said first radiation intensity data to determine a clear wood density threshold value for the lumber piece and a maximum density value of said density profiles; and

f) computer readable program code means for causing the computing of a ratio of the summed density profile values to the summed maximum density values for said density profiles and the multiplication of the ratio with the transverse width of the lumber piece.

5. The computer program product of claim 4 wherein said ratio is

ratio

=

Σ

⁢

⁢

measured

⁢

⁢

knot

⁢

⁢

density

-

Σ

⁢

⁢

measured

⁢

⁢

clear

⁢

⁢

density

Σ

⁢

⁢

max

⁢

⁢

knot

⁢

⁢

density

-

Σ

⁢

⁢

measured

⁢

⁢

clear

⁢

⁢

density

.

6. The computer program product of claim 5 for use with a device having a second radiation source cooperating with a second radiation sensor,

wherein the device simultaneously irradiates said lumber piece during said translation along said flow path with radiation from said second radiation source,

said computer program product further comprising:

a) computer readable program code means for causing the collection of a set of second radiation intensity data from said second radiation sensor as said lumber piece is irradiated during said translation; and

b) computer readable program code means for causing the processing of said second radiation intensity data together with said first set of three dimensional density profiles to provide a second set of three dimensional density profiles of said lumber piece merging said first and second sets.

7. The computer program product of claim 6 wherein said first radiation sensor comprises a plurality of radiation sensors.

8. The computer program product of claim 6 wherein said second radiation sensor comprises a plurality of radiation sensors.