plotCamera
Plot a camera in 3-D coordinates
Description
plots a default
camera in 3-D coordinates in the current axes. The function returns
cam
= plotCameracam
, a Camera
object that contains
the properties of the plotted camera.
plots one or more cameras specified by cam
= plotCamera(cameraTable
)cameraTable
.
specifies options using one or more name-value arguments in addition to any
combination of arguments from previous syntaxes. For example,
cam
= plotCamera(Name=Value
)Opacity=0.4
sets the opacity of the plotted camera to
0.4
.
The name-value pair arguments set the associated properties of the plotted camera visualization object.
Examples
Plot Animated Camera Using Absolute Pose
Create a rigidtform3d
object.
initialRotation = [1 0 0; 0 0 1; 0 -1 0]; initialTranslation = [10 0 20]; pose = rigidtform3d(initialRotation,initialTranslation);
Plot a camera with an opacity of zero and an absolute pose based on the created rigidtform3d
object.
cam = plotCamera(AbsolutePose=pose,Opacity=0)
cam = Camera with properties: Parent: [1x1 Axes] Size: 1 AbsolutePose: [1x1 rigidtform3d] Visible: 1 AxesVisible: 0 ButtonDownFcn: '' Color: [1 0 0] Opacity: 0 Label: ''
Set viewing properties for the current axes.
grid on axis equal axis manual
Expand the viewable limits of each axis. These changes enable the entire animation to be visible in the next step.
xlim([-15 20]); ylim([-15 20]); zlim([15 25]);
Rotate the camera around the y-axis.
for theta = 0:10:1800 updateAngles = [0 -theta 0]; updateTranslation = [10*cosd(theta) 10*sind(theta) 20]; updateTform = rigidtform3d(updateAngles, updateTranslation); cam.AbsolutePose = rigidtform3d(initialRotation * updateTform.R, updateTform.Translation); drawnow(); end
Visualize Camera Extrinsics
Create a set of calibration images.
imds = imageDatastore(fullfile(toolboxdir("vision"),"visiondata","calibration","slr"));
Detect the checkerboard corners in the images.
[imagePoints,boardSize] = detectCheckerboardPoints(imds.Files);
Generate the world coordinates of the checkerboard corners in the pattern-centric coordinate system, with the upper-left corner at (0,0). Set the square size to 29 mm.
squareSize = 29;
worldPoints = patternWorldPoints("checkerboard",boardSize,squareSize);
Load an image at its new location.
imOrig = imread(fullfile(toolboxdir("vision"),"visiondata","calibration","slr","image9.jpg")); figure; imshow(imOrig,InitialMagnification=50); title("Input Image");
Calibrate the camera.
cameraParams = estimateCameraParameters(imagePoints,worldPoints,"ImageSize",size(imOrig,1:2));
Undistort the image.
im = undistortImage(imOrig,cameraParams.Intrinsics);
Find the reference object in the new image.
[imagePoints,boardSize] = detectCheckerboardPoints(im);
Compute the new extrinsics.
camExtrinsics = estimateExtrinsics(imagePoints,worldPoints,cameraParams.Intrinsics);
Plot the world points.
figure; plot3(worldPoints(:,1),worldPoints(:,2),zeros(size(worldPoints, 1),1),"*"); hold on
Mark the origin.
plot3(0,0,0,"g*");
Compute the camera location and orientation.
absPose = extr2pose(camExtrinsics);
Plot the camera.
cam = plotCamera(AbsolutePose=absPose,Size=20);
Make the z -axis point down.
set(gca,CameraUpVector=[0 0 -1]);
Set the view parameters.
camorbit(gca,-110,60,data=[0 0 1]); axis equal grid on
Turn on 3-D rotation.
cameratoolbar('SetMode','orbit');
Label the axes.
xlabel("X (mm)"); ylabel("Y (mm)"); zlabel("Z (mm)");
Input Arguments
cameraTable
— Properties of cameras for visualization
table
Properties of cameras for visualization, specified as a table. Each row
represents a single camera. Each column title must match the name-part of a
name-value pair argument. The nth-row values set the
properties for the nth element of
cam
. You cannot specify values for
Parent
. If the table contains a
ViewId
column, then the view IDs are used to set the
Label
values of the cameras.
Name-Value Arguments
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: Size=0.3
specifies the camera-base width as
0.3
.
AbsolutePose
— Camera absolute pose
rigidtform3d
object
Camera absolute pose in the world coordinate system, specified as a
rigidtform3d
object.
Size
— Camera-base width
1
(default) | positive real number
Camera-base width, specified as a positive real number.
Label
— Camera label
''
(default) | character vector | string scalar
Camera label, specified as a character vector or a string scalar.
Color
— Camera color
[1 0 0]
(red) (default) | RGB triplet
Camera color, specified as an RGB triplet. An RGB triplet is a three-element row vector whose elements specify the intensities of the red, green, and blue components of the color. The intensities must be in the range [0, 1].
Opacity
— Camera opacity
0.2
(default) | scalar in the range [0, 1]
Camera opacity, specified as a scalar in the range [0, 1].
Visible
— Camera visibility
true
or
1
(default) | false
or 0
Camera visibility, specified as a numeric or logical
1
(true
) or
0
(false
).
AxesVisible
— Camera axes visibility
false
or
0
(default) | true
or 1
Camera axes visibility, specified as a numeric or logical
1
(true
) or
0
(false
).
ButtonDownFcn
— Callback function
''
(default) | function handle
Callback function, specified as a function handle that executes when you click the camera.
Parent
— Output axes
axes
handle
Output axes, specified as an axes handle. By default,
plotCamera
uses the current axes handle. To
return the current axes, use the gca
function.
Output Arguments
cam
— Camera visualization object
Camera
object | row vector of Camera
objects
Camera visualization object, returned as one of these options.
Camera
object — The function returns this option when plotting a single camera. Name-value arguments orcameraTable
input elements set the correspondingCamera
object properties.Row vector of
Camera
objects — The function returns this option when plotting multiple cameras. The nth -row values of thecameraTable
input set the properties for the nthCamera
object in this vector.
Camera objects are created using the
vision.graphics.Camera
class, which contains the
following properties:
Version History
Introduced in R2015aR2022b: Specify AbsolutePose
as a rigidtform3d
object
Starting in R2022b, most Computer Vision Toolbox™ functions create and perform geometric transformations using the
premultiply convention. Accordingly, you can now specify the
AbsolutePose
name-value argument as a rigidtform3d
object, which uses the premultiply convention.
Although you can still specify AbsolutePose
as a rigid3d
object, this object is not recommended because it uses the postmultiply convention.
You can streamline your geometric transformation workflows by switching to the new
premultiply geometric transformation objects. For more information, see Migrate Geometric Transformations to Premultiply Convention.
R2020a: The Location
and Orientation
properties belonging to the plotCamera
function are removed
The plotCamera
function now accepts a
rigid3d
object to specify a camera pose. Starting in R2020a, you must use the rigid3d
object instead of the Location
and Orientation
properties to specify the pose.
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