# Documentation

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# KAZEPoints

Object for storing KAZE interest points

## Description

This object provides the ability to pass data between the detectKAZEPoints and extractFeatures functions. You can also use this object to manipulate and plot the data returned by these functions.Use the object to fill points interactively, where you might want to mix a non-KAZE interest oint detector with a KAZE descriptor.

## Creation

### Syntax

points = KAZEPoints(location)
points = KAZEPoints(I,Name,Value)

### Description

example

points = KAZEPoints(location) constructs a KAZEPoints object from an M-by-2 array [x y] of location coordinates.

The scalar KAZEPoints object contains many points. Therefore numel(KAZEPoints) always returns 1. This value can be different than the result of length(KAZEPoints), which returns the true number of points contained in the object.

example

1points = KAZEPoints(I,Name,Value) constructs a KAZEPoints object with additional properties specified by one or more Name,Value pair arguments

## Properties

expand all

Scale, specified as a scalar. The scale sets the size at which the interest points are detected.

Strength of response for the detected points, specified as a numeric value. The KAZE algorithm uses a determinant of an approximated Hessian.

Orientation of the detected feature, specified as an angle in radians. The angle is measured from the x-axis with the origin set by the location input. The extractFeatures function sets this property. Do not set it manually.

## Object Functions

 isempty Determine if KAZE points object is empty length Number of stored KAZE points plot Plot KAZE points selectStrongest Select KAZE points with strongest metrics selectUniform Select uniformly distributed subset of KAZE feature points

## Examples

expand all

Detect KAZE features and display 10 strongest points.

Detect KAZE features in the image.

points = detectKAZEFeatures(I);

Select the 10 strongest points.

strongest = selectStrongest(points,10);

Display the selected points.

imshow(I);
hold on;

Display the location and scale. The size of the circles displayed relate to the scale.

plot(strongest);
hold on;

Display the [x y] coordinates for the strongest points in the MATLAB Command Window.

strongest.Location
ans = 10×2 single matrix

138.5041   95.8063
139.9253   95.8802
111.8975   48.2950
106.4036  174.1800
44.3964  106.4899
122.0368   65.9064
116.2702  138.2877
123.6542   64.7193
104.2719   76.5821
140.6228   97.9271

Detect KAZE features and display set the specific KAZE points you want to plot.

Detect KAZE features in the image.

points = detectKAZEFeatures(I);

Select and display the last 5 points detected.

imshow(I);
hold on;
plot(points(end-4:end));
hold off;