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Tolerance interval approach
B-spline representation- representation of curves using piecewise polynomial interpolation
to obtain smooth curves is widely used in computer graphics. B-splines are piecewise
polynomial curves whose shape is closely related to their control polygon- a chain of vertices
giving a polygonal representation.
Other contour based shape description approaches.
Faculty of Engineering Robotics Technology MECH 4041 27
B.Eng (Hons.) Mechatronics S. Venkannah Mechanical and Production Engineering Department Hough transform
Region based shape representation and description.
Area- simplest and most natural property of a region in its area, given by the number of
pixels of which the region consists. If an image is represented as a rectangular raster,
simple counting of region pixels will provide its area. If the image is represented by a
quadtree, however, it may more difficult to find the region area.
Euler’s number- describes a simple, topologically invariant property of the object. It is
based on S, the number of contiguous parts of an object, and N, the number of holes in the
Eccentricity- the simplest eccentricity is the ratio of the length of the maximum chord A
to the maximum chord B which is perpendicular to A (the ration of the major and minor
axes of an object)
Elongatedness- the ratio between the length and width of the region bounding rectangle.
This is the rectangle of minimum area that bounds the shape, which is located by turning
in discrete steps until a minimum is located.
RectangularityDirection- a property which makes sense in elongated regions only. If the region is
elongated, direction is the direction of the longer side of a minimum bounding rectangle.
Compactness- a popular shape description characteristic independent of linear
transformation given by
Compactness= ( region_border_length)2 / area
Moments- region moment representations interpret a normalized gray-level image
function as a probability density of a 2D random varia...
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