checkStatus

Check status of stereo visual SLAM object

Since R2025a

Syntax

status = checkStatus(vslam)

Description

status = checkStatus(vslam) returns the current status of the stereo visual SLAM object. The frame the object is currently processing might be different than the most recently added frame.

Examples

Stereo Visual SLAM Using UTIAS Data Set

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

reset(vslam)

Input Arguments

vslam — Stereo visual SLAM object

stereovslam object

Stereo visual SLAM object, specified as a stereovslam object.

Output Arguments

status — Current status of stereo visual SLAM object

TrackingLost enumeration | TrackingSuccessful enumeration | FrequentKeyFrames enumeration

Current status of the stereo visual SLAM object, returned as a TrackingLost, TrackingSuccessful, or FrequentKeyFrames enumeration. This table describes these enumerations.

Enumeration Value	Numeric Value	Description
TrackingLost	uint8(0)	Tracking is lost. The number of tracked feature points in the frame currently being processed is less than the lower limit of the TrackFeatureRange property of vslam. This indicates the image does not contain enough features, or that the camera is moving too fast. If the object does not accept enough frames as key frames, to improve tracking, you can increase the upperLimit value of the TrackFeatureRange property and decrease the SkipMaxFrames property to add key frames more frequently.
TrackingSuccessful	uint8(1)	Tracking is successful. The number of tracked feature points in the frame currently being processed is between the lower limit and upper limit values of the TrackFeatureRange property of vslam.
FrequentKeyFrames	uint8(2)	Tracking adds key frames too frequently. The number of tracked feature points in the frame currently being processed is greater than the upper limit of the TrackFeatureRange property of vslam.

Version History

Introduced in R2025a