Chapter Questions
What are the prerequisites of shape description?
What are the main distinguishing aspects among various shape representation and shape description methods?
Explain how high or low image resolution affects shape descriptors, their discriminability and repeatability.
Explain the rationale behind projection-invariant shape descriptors.
Define the three most common representations of region borders.
Define the boundary chain code in 4- and 8-connectivity.
Define the chain code derivative in 4- and 8-connectivity.
An object is described by the following chain code in 4-connectivity: 10123230.(a) Determine the normalized version of the chain code.(b) Determine the derivative of the original chain code.
What is a chord distribution for a shape?
Explain the concept of multi-scale curve description using interval trees in the scale space.
Describe the concept of B-spline curve interpolation.
Define the following projection-invariant shape descriptors:(a) Cross ratio(b) System of four co-planar concurrent lines(c) System of five co-planar concurrent lines(d) System of five co-planar points(e) Plane conics
Describe a subclass of boundary shapes to which the invariants listed in Question S8.13 can be applied.
Explain the difference between local and global invariants.
Determine the Euler number of the following characters: $0,4,8, A, B, C, D$.
Define the following region shape descriptors:(a) Area(b) Euler's number(c) Horizontal and vertical projections(d) Eccentricity(e) Elongatedness(f) Rectangularity(g) Direction(h) Compactness(i) Statistical moments(j) Convex hull(k) Region concavity tree
Describe the principles of region skeletonization by thinning.
Describe the medial axis transform.
Sketch the skeleton of two touching filled circles.
Name the main desirable properties of object/region skeletons. Which ones of them (which pairs) are mutually contradictory?
Describe the principles of shape description using graph decomposition.
Explain what shape classes are and why are they important.