Eccentricity, Max radius and max radius position, Min radius and min radius position – Banner PresencePLUS P4 Series User Manual

Page 119: 4 analysis tools, Eccentricity7.3.2.6.2.6 eccentricity

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The table below gives a more practical perspective on how to interpret these results. If the camera is configured
to convert pixels to other units, the major and minor axis lengths will be given in those units. The major axis
angle is always given in degrees.

Meaning of Major Axis
angle

Meaning of Minor Axis
Length

Meaning of Major Axis
Length

Blob Shape

unstable

equal to the major axis
length

diameter of the circle

circular, no holes

orientation of the ellipse

width of the ellipse

length of the ellipse

elliptical, no holes

unstable

equal to the major axis
length

diameter of a circle that
best approximates the
square

square, no holes

orientation of the rectangle

width of an ellipse that
best approximates the
rectangle

length of an ellipse that
best approximates the
rectangle

rectangular, no holes

orientation of the
shape-unstable if length
and with are nearly equal

width of an ellipse that
best approximates the
shape

length of an ellipse that
best approximates the
shape

complicated shape, no
holes

results vary depending on
exact shape-experiment
on your particular shape

results vary depending on
exact shape-experiment
on your particular shape

results vary depending on
exact shape-experiment
on your particular shape

any shape with holes

Eccentricity

The eccentricity of a blob is defined as the length of the major axis divided by the length of the minor axis. For
circular regions and other regions with radial symmetry (like a square), the value will be very close to 1. For
elongated regions, the value will grow, possibly becoming quite large.

Max Radius and Max Radius Position

These results are equivalent to those for the minimum radius, but they refer to the pixel on the perimeter of
the blob that is farthest from the centroid .

Min Radius and Min Radius Position

The minimum radius of a blob is the distance from the centroid of the blob to the closest pixel on that blob's
perimeter. The minimum radius position gives the pixel coordinates of that closest perimeter point. If the blob
contains unfilled holes, the minimum radius position may be on the perimeter of a hole. If the camera is
configured to convert pixels to other units, the minimum radius (but not the minimum radius position) will be
given in those units.

7.4 Analysis Tools

Analysis tools analyze the information gathered with the Vision tools to create measurements and tolerances
for the Vision tools.

Analysis Tools

119

Banner Engineering Corp. - Minneapolis, MN USA - www.bannerengineering.com

Tel: 763.544.3164

P/N 000000

PresencePLUS Software Tools

7/2009

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