M-File Help: PointFeature | View code for PointFeature |
PointCorner feature object
A superclass for image corner features.
plot | Plot feature position |
distance | Descriptor distance |
ncc | Descriptor similarity |
uv | Return feature coordinate |
display | Display value |
char | Convert value to string |
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.
ScalePointFeature, SurfPointFeature, SiftPointFeature
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.
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.
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.
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.
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.
'thresh', T | Match threshold (default 0.05) |
'median' | Threshold at the median distance |
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.
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.