Dual mode video tracker

Claim 1

A method of establishing a size of a correlation tracking gate in a correlation tracking system of a type which generates tracking error signals from input electromagnetic video signals V i ,j (k) utilized to form one video frame k of a two dimensional image plane having coordinates (ε,η) where ε represents an elevation and η represents an azimuth, said image plane being defined by a plurality of pixels each having a discrete location (i,j) in the image plane along coordinates ε and η respectively and wherein said tracking gate is defined by N×M pixels along coordinates η and ε respectively, said method comprising the steps of: (a) generating a reference map value for each pixel according to the relationship MAP.sub.ij (k)=W.sub.1 V.sub.ij (k)+(1-W.sub.1)MAP.sub.ij (k-1) where W 1 is a weighting factor having a value 0≦W 1 ≦1; (b) generating a first weighting function We ij (k) related to relative values of pairs of pixels along the ε coordinate; (c) generating a second weighting function Wd ij (k) related to relative values of pairs of pixels along the η coordinate; (d) generating first and second respective correlation error signals δ' d (k) and δ' e (k) for each image plane frame using the first and second weighting functions We ij (k) and Wd ij (k); (e) generating a gradient function GF ij (k) for each pixel within a gradient gate defined by YxZ pixels, according to the relationship GF.sub.ij (k)=[We.sub.ij (k)].sup.2 +[Wd.sub.ij (k)].sup.2, said gradient function GF ij (k) representing a measure of information content within the tracking gate; and (f) altering the size of said tracking gate using the gradient function GF ij (k) generated in step (e).

Claim 2

A method of establishing a size of a correlation tracking gate in a correlation tracking system of a type which generates tracking error signals from input electromagnetic video signals V i ,j (k) utilized to form one video frame k of a two dimensional image plane having coordinates (ε,η) where ε represents an elevation and η represents an azimuth, said image plane being defined by a plurality of pixels each having a discrete location (i,j) in the image plane along coordinates ε and η respectively and wherein said tracking gate is defined by N×M pixels along coordinates η and ε respectively, said method comprising the steps of: (a) generating a reference map value for each pixel according to the relationship MAP.sub.ij (k)=W.sub.1 V.sub.ij (k)+(1-W.sub.1)MAP.sub.ij (k-1) where W 1 is a weighting factor having a value 0≦W 1 ≦1; (b) generating a first weighting function We ij (k) related to relative values of pairs of pixels along the ε coordinate; (c) generating a second weighting function Wd ij (k) related to relative values of pairs of pixels along the η coordinate; (d) generating first and second respective correlation error signals δ' d (k) and δ' e (k) for each image plane frame using the first and second weighting functions We ij (k) and Wd ij (k); (e) generating a gradient function GF ij (k) for each pixel within a gradient gate defined by YxZ pixels, according to the relationship GF.sub.ij (k)=[We.sub.ij (k)].sup.2 +[Wd.sub.ij (k)].sup.2, said gradient function GF ij (k) representing a measure of information content within the tracking gate; and (f) altering the size of said tracking gate using the gradient function GF ij (k) generated in step (e).

Claim 10

A method of determining correlation track quality in a correlation tracking system of a type which generates tracking quality error signals from input electromagnetic video signals V ij (k) utilized to form one video frame k of a two dimensional image plane having coordinates (ε,η) where ε represents an elevation and η represents an azimuth, said image plane being defined by a plurality of pixels each having a discrete location (i,j) in the image plane along coordinates ε and η respectively, and wherein correlation is performed over a track gate defined by NxM pizels along coordinates and respectively, said method comprising the steps of: (a) recursively generating a reference map value for each pixel according to the relationship MAP.sub.ij (k)=W.sub.1 V.sub.ij (k)+(1-W.sub.1)MAP.sub.ij (k-1) where W 1 is a weighting factor having a value of 0≦W 1 ≦1; (b) subtracting reference map values MAP ij (k) from the video signals V ij (k) of a subsequent frame to produce a difference video ΔV ij (k); (c) generating a first weighting function We ij (k) related to pixels along the ε coordinate; (d) generating a second weighting function Wd ij (k) related to pixels along the η coordinate; (e) generating first and second respective correlation error signals δ' d (k) and δ' e (k) for each image plane frame using said first and second weighting functions We ij (k) and Wd ij (k); (f) defining border gates outside of and adjacent to said track gate, summing a value of the difference video ΔV ij (k) over said track gate for each image plane frame to produce a track gate sum; and summing the difference video ΔV ij (k) over said border gates for each image plane frame to produce a border gate sum; (g) generating a gradient function GF ij (k) for each pixel in a gradient gate defined by YxZ pixels according to the relationship GF.sub.ij (k)=[We.sub.ij (k)].sup.2 +[Wd.sub.ij (k)].sup.2 ; (h) summing the gradient function GF ij (k) over the gradient gate for each image plane to produce a gradient function sum; and, (i) generating an indication of track quality using the track gate sum, border gate sum and gradient function sum.

Claim 11

A method of determining correlation track quality in a correlation tracking system of a type which generates tracking quality error signals from input electromagnetic video signals V ij (k) utilized to form one video frame k of a two dimensional image plane having coordinates (ε,η) where ε represents an elevation and η represents an azimuth, said image plane being defined by a plurality of pixels each having a discrete location (i,j) in the image plane along coordinates ε and η respectively, and wherein correlation is performed over a track gate defined by NxM pizels along coordinates and respectively, said method comprising the steps of: (a) recursively generating a reference map value for each pixel according to the relationship MAP.sub.ij (k)=W.sub.1 V.sub.ij (k)+(1-W.sub.1)MAP.sub.ij (k-1) where W 1 is a weighting factor having a value of 0≦W 1 ≦1; (b) subtracting reference map values MAP ij (k) from the video signals V ij (k) of a subsequent frame to produce a difference video ΔV ij (k); (c) generating a first weighting function We ij (k) related to pixels along the ε coordinate; (d) generating a second weighting function Wd ij (k) related to pixels along the η coordinate; (e) generating first and second respective correlation error signals δ' d (k) and δ' e (k) for each image plane frame using said first and second weighting functions We ij (k) and Wd ij (k); (f) defining border gates outside of and adjacent to said track gate, summing a value of the difference video ΔV ij (k) over said track gate for each image plane frame to produce a track gate sum; and summing the difference video ΔV ij (k) over said border gates for each image plane frame to produce a border gate sum; (g) generating a gradient function GF ij (k) for each pixel in a gradient gate defined by YxZ pixels according to the relationship GF.sub.ij (k)=[We.sub.ij (k)].sup.2 +[Wd.sub.ij (k)].sup.2 ; (h) summing the gradient function GF ij (k) over the gradient gate for each image plane to produce a gradient function sum; and, (i) generating an indication of track quality using the track gate sum, border gate sum and gradient function sum.