plot

Plot 3-D map points and estimated camera trajectory in stereo visual SLAM

Since R2024a

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    Syntax

    plot(vslam)
    plot(vslam,Name=Value)
    ax = plot(___)

    Description

    plot(vslam) plots the 3-D map points and estimated camera trajectory from the visual SLAM object vslam.

    example

    plot(vslam,Name=Value) specifies options using one or more name-value arguments. For example, MarkerSize=10 sets the diameter of the marker size to 10 points.

    ax = plot(___) returns the axes handle for the 3-D mapped points of the plot, using any combination of input arguments from previous syntaxes.

    Examples

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    Open Live Script

    Perform stereo visual simultaneous localization and mapping (vSLAM) using the data from the UTIAS Long-Term Localization and Mapping Dataset provided by University of Toronto Institute for Aerospace Studies. You can download the data to a directory using a web browser, or by running this code:

    ftpObj = ftp("asrl3.utias.utoronto.ca");
tempFolder = fullfile(tempdir);
dataFolder = [tempFolder,'2020-vtr-dataset\UTIAS-In-The-Dark\'];
zipFileName = [dataFolder,'run_000005.zip'];
folderExists = exist(dataFolder,"dir");

    Create a folder in a temporary directory to save the downloaded file and extract its contents.

    if ~folderExists  
    mkdir(dataFolder) 
    disp("Downloading run_000005.zip (818 MB). This download can take a few minutes.") 
    mget(ftpObj,"/2020-vtr-dataset/UTIAS-In-The-Dark/run_000005.zip",tempFolder);

    disp("Extracting run_000005.zip (818 MB) ...") 
    unzip(zipFileName,dataFolder); 
end

    Create two imageDatastore objects to store the stereo images.

    imgFolderLeft = [dataFolder,'\images\left\'];
imgFolderRight = [dataFolder,'\images\right\'];
imdsLeft = imageDatastore(imgFolderLeft);
imdsRight = imageDatastore(imgFolderRight);

    Specify the intrinsic parameters and the baseline of the stereo camera, and use them to create a stereo visual SLAM object. The focal length, principal point, and image size is in pixels, and the baseline is in meters.

    focalLength = [387.777 387.777];  
principalPoint = [257.446 197.718];  
imageSize = [384 512];            
intrinsics = cameraIntrinsics(focalLength,principalPoint,imageSize);
baseline = 0.239965; 

vslam = stereovslam(intrinsics,baseline,MaxNumPoints=600, ...
    TrackFeatureRange=[30 120],SkipMaxFrames=5);

    Process each pair of stereo images and visualize the camera poses and 3-D map points.

    for i = 1:numel(imdsLeft.Files)
    leftImage = readimage(imdsLeft,i);
    rightImage = readimage(imdsRight,i);
    addFrame(vslam,leftImage,rightImage);

    if hasNewKeyFrame(vslam)
        % Query 3-D map points and camera poses
        xyzPoints = mapPoints(vslam);
        [camPoses,viewIds] = poses(vslam);

        % Display 3-D map points and camera trajectory
        plot(vslam);
    end

    % Get current status of system
    status = checkStatus(vslam);
    
    % Stop adding frames when tracking is lost
    if status == uint8(0)
        break
    end
end

    Once all the frames have been processed, reset the system.

    while ~isDone(vslam)
    plot(vslam)
end

    Figure contains an axes object. The axes object with xlabel X, ylabel Y contains 12 objects of type line, text, patch, scatter. This object represents Camera trajectory.

    reset(vslam)

    Input Arguments

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    Stereo visual SLAM object, specified as a stereovslam object.

    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.

    Example: plot(vslam,MarkerSize=10), sets the diameter of the marker to 10 points.

    Diameter of markers for the 3-D map points, specified as a positive integer in points.

    Color of the markers for the 3-D map points, specified as an RGB triplet or a short or long color name. Each value within an RGB triplet must be in the range [0 1].

    Colormap source for markers, specified as "X", "Y", "Z", or "MarkerColor".

    Width of the camera base, specified as a positive scalar in the data units of the axes.

    Color of the camera, specified as an RGB triplet or a short or long color name. Each value within an RGB triplet must be in the range [0 1].

    Axes for visualization, specified as an Axes graphics object or a UIAxes object. Use this name-value argument to visualize the plot in a UI for which you have specified Figure and Axes properties.

    Output Arguments

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    Axes handle, returned as an axes graphics object.

    Version History

    Introduced in R2024a

    See Also

    Objects

    Functions