M-File Help: PointFeature View code for PointFeature

PointFeature

PointCorner feature object

A superclass for image corner features.

Methods

plot Plot feature position
distance Descriptor distance
ncc Descriptor similarity
uv Return feature coordinate
display Display value
char Convert value to string

Properties

u horizontal coordinate
v vertical coordinate
strength feature strength
descriptor feature descriptor (vector)

Properties of a vector of PointFeature objects are returned as a vector. If F is a vector (Nx1) of PointFeature objects then F.u is a 2xN matrix with each column the corresponding point coordinate.

See also

ScalePointFeature, SurfPointFeature, SiftPointFeature


PointFeature.PointFeature

Create a point feature object

f = PointFeature() is a point feature object with null parameters.

f = PointFeature(u, v) is a point feature object with specified coordinates.

f = PointFeature(u, v, strength) as above but with specified strength.


PointFeature.char

Convert to string

s = F.char() is a compact string representation of the point feature. If F is a vector then the string has multiple lines, one per element.


PointFeature.display

Display value

F.display() displays a compact human-readable representation of the feature. If F is a vector then the elements are printed one per line.

Notes

See also

PointFeature.char


PointFeature.distance

Distance between feature descriptors

d = F.distance(f1) is the distance between feature descriptors, the norm of the Euclidean distance.

If F is a vector then d is a vector whose elements are the distance between the corresponding element of F and f1.


PointFeature.match

Match point features

m = F.match(f2, options) is a vector of FeatureMatch objects that describe candidate matches between the two vectors of point features F and f2.

[m,C] = F.match(f2, options) as above but returns a correspodence matrix where each row contains the indices of corresponding features in F and f2 respectively.

Options

'thresh', T Match threshold (default 0.05)
'median' Threshold at the median distance

See also

FeatureMatch


PointFeature.ncc

Feature descriptor similarity

s = F.ncc(f1) is the similarty between feature descriptors which is a scalar in the interval -1 to 1, where 1 is perfect match.

If F is a vector then D is a vector whose elements are the distance between the corresponding element of F and f1.


PointFeature.plot

Plot feature

F.plot() overlay a marker at the feature position.

F.plot(ls) as above but the optional line style arguments ls are passed to plot.

If F is a vector then each element is plotted.


 

© 1990-2012 Peter Corke.