plot

Plot detected feature points

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Syntax

plot(points)
plot(points,ax)
plot(points,ax,Name=Value)

Description

plot(points) plots detected feature points in the current axis. The input points is a feature point object that stores the locations and related information of the detected features.

example

plot(points,ax) displays feature points in the specified axis.

plot(points,ax,Name=Value) specifies options using one or more name-value arguments in addition to any combination of arguments from previous syntaxes. For example, plot(ShowOrientation=true) renders the orientation in the display plot.

Examples

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Open Live Script

Read an image.

I = imread("cameraman.tif");

Detect KAZE points from the image.

points = detectKAZEFeatures(I);

Extract KAZE features from the detected points.

[features,valid_points] = extractFeatures(I,points);

Plot the 10 strongest points and show their orientations.

imshow(I)
hold on
strongestPoints = selectStrongest(valid_points,10);
plot(strongestPoints,showOrientation=true)
hold off

Figure contains an axes object. The hidden axes object contains 3 objects of type image, line. One or more of the lines displays its values using only markers

Open Live Script
I = imread("cameraman.tif");
points = detectSURFFeatures(I);
[features, valid_points] = extractFeatures(I,points);

Visualize 10 strongest SURF features, including their scales and orientation which were determined during the descriptor extraction process.

imshow(I); 
hold on;
strongestPoints = valid_points.selectStrongest(10);
strongestPoints.plot("showOrientation",true);

Figure contains an axes object. The hidden axes object contains 3 objects of type image, line. One or more of the lines displays its values using only markers

Input Arguments

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Points object,specified as an M-by-2 matrix of M number of [x y] coordinates, or as one of the point feature objects described in Point Feature Types. The object contains information about the feature points detected in the input image. To obtain points, use the appropriate detect function that pairs with the point feature type.

Handle to use for display. You can set the handle using gca.

Name-Value Arguments

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Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: plot(ShowOrientation=true) renders the orientation in the display plot.

Display scaled circle, specified as true or false. When you set this value to true, the object draws a circle proportional to the scale of the detected feature, with the feature point located at its center. When you set this value to false, the object turns the display of the circle off.

The algorithm represents the scale of the feature with a circle of 6*Scale radius. The algorithm uses this equivalent size of circular area to compute the orientation of the feature.

Display feature point orientation, specified as true or false. When you set this value to true, the object draws a line corresponding to the point's orientation. The object draws the line from the feature point location to the edge of the circle, indicating the scale.

Version History

Introduced in R2011b

See Also

Functions