bbox2points

Convert rectangle to corner points list

Syntax

points = bbox2points(rectangle)

Description

points = bbox2points(rectangle) converts the input rectangle, into a list of four [x y] corner points. The rectangle input must be either a single bounding box or a set of bounding boxes.

Examples

Convert Bounding Box to List of Points and Apply Rotation

Define a bounding box.

bbox = [10,20,50,60];

Convert the bounding box to a list of four points.

points = bbox2points(bbox);

Define a rotation transformation.

theta = 10;
tform = affine2d([cosd(theta) -sind(theta) 0; sind(theta) cosd(theta) 0; 0 0 1]);

Apply the rotation.

points2 = transformPointsForward(tform,points);

Close the polygon for display.

points2(end+1,:) = points2(1,:);

Plot the rotated box.

plot(points2(:,1),points2(:,2), '*-');

Input Arguments

rectangle — Bounding box

4-element vector | 5-element vector | M-by-4 matrix | M-by-5 matrix

Bounding box, specified as a 4-element vector, 5-element vector, M-by-4 matrix, or M-by-5 matrix.

Bounding Box	Example
For one or more rectangles, specify one of: An M-by-4 matrix where each row specifies a rectangle as $$\left[\begin{array}{cccc}x& y& width& height\end{array}\right]$$. $$\left[\begin{array}{cccc}{x}_1& y_1& widt{h}_1& heigh{t}_1\\ x_2& y_2& widt{h}_2& heigh{t}_2\\ ⋮& ⋮& ⋮& ⋮\\ x_M& y_M& widt{h}_M& heigh{t}_M\end{array}\right]$$ An M-by-5 numeric matrix with rows of the form [xctr yctr w h yaw], where: M is the number of rotated rectangles. xctr and yctr specify the center of the rectangle. w specifies the width of the rectangle, which is its length along the x-axis before rotation. h specifies the height of the rectangle, which is its length along the y-axis before rotation. yaw specifies the rotation angle in degrees. The rotation is clockwise-positive around the center of the bounding box.

Data Types: single | double | int16 | int32 | uint16 | uint32

Output Arguments

points — Rectangle corner coordinates

4-by-2 matrix | 4-by-2-by-M array

Rectangle corner coordinates, returned as a 4-by-2 matrix of [x,y] coordinates, or a 4-by-2-by-M array of [x,y] coordinates. The output points for the rectangle are listed counterclockwise starting from the upper-left corner.

• For a single input bounding box, the function returns the 4-by-2 matrix.

• For multiple input bounding boxes, the function returns the 4-by-2-M array for M bounding boxes.

Data Types: single | double | int16 | int32 | uint16 | uint32

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2014b