Object for storing BRISK interest points
This object provides the ability to pass data between the detectBRISKFeatures and extractFeatures functions. You can also use it to manipulate and plot the data returned by these functions. You can use the object to fill the points interactively in situations where you might want to mix a non-BRISK interest point detector with a BRISK descriptor.
Although BRISKPoints can hold many points, it is a scalar object. Therefore, NUMEL(BRISKPoints) always returns 1. This value can differ from LENGTH(BRISKPoints), which returns the true number of points held by the object.
points = BRISKPoints(Location) constructs a BRISKPoints object from an M-by-2 array of [x y] point coordinates, Location.
points = BRISKPoints(Location,Name,Value) constructs a BRISKPoints object with optional input properties specified by one or more Name,Value pair arguments. You can specify each additional property as a scalar or a vector whose length matches the number of coordinates in Location.
|Code Generation Support|
|Compile-time constant inputs: No restriction.|
|Supports MATLAB Function block: No|
|To index locations with this object, use the syntax: points.Location(idx,:), for points object. See visionRecovertformCodeGeneration_kernel.mvisionRecovertformCodeGeneration_kernel.m, which is used in the Introduction to Code Generation with Feature Matching and Registration example.|
|Code Generation Support, Usage Notes, and Limitations|
Point locations, specified as an M-by-2 array of [x y] point coordinates.
Scale at which the feature is detected, specified as a value greater than or equal to 1.6.
Strength of detected feature, specified as a numeric value. The BRISK algorithm uses a determinant of an approximated Hessian.
Orientation of the detected feature, specified as an angle, in radians. The angle is measured counterclockwise from the X-axis with the origin specified by the Location property. Do not set this property manually. Use the call to extractFeatures to fill in this value. The extractFeatures function modifies the default value of 0.0. Using BRISK interest points to extract a non-BRISK descriptor, (e.g. SURF, FREAK, MSER, etc.), can alter Orientation values. The Orientation is mainly useful for visualization purposes.
Number of points held by the BRISK object, specified as a numeric value.
|isempty||Returns true for empty object|
|length||Number of stored points|
|plot||Plot BRISK points|
|selectStrongest||Return points with strongest metrics|
|size||Size of the BRISKPoints object|
I = imread('cameraman.tif'); points = detectBRISKFeatures(I);
strongest = points.selectStrongest(10); imshow(I); hold on; plot(strongest);
ans = 136.4033 55.5000 155.6964 83.7577 197.0000 233.0000 117.3680 92.3680 147.0000 162.0000 104.0000 229.0000 129.7972 68.2028 154.8790 77.0000 118.0269 174.0269 131.0000 91.1675
 Leutenegger, S., M. Chli, and R. Siegwart. BRISK: Binary Robust Invariant Scalable Keypoints, Proceedings of the IEEE International Conference on Computer Vision (ICCV) 2011.