mapPoints

Build 3-D map of world points from RGB-D vSLAM object

Since R2024a

Syntax

xyzPoints = mapPoints(vslam)

Description

xyzPoints = mapPoints(vslam) builds a sparse 3-D map of world points, xyzPoints, from the input images in the RGB-D visual simultaneous localization and mapping (vSLAM) object vslam.

Examples

RGB-D Visual SLAM Using TUM RGB-D Data Set

Perform RGB-D visual simultaneous localization and mapping (vSLAM) using the data from the TUM RGB-D Benchmark. You can download the data to a temporary directory using a web browser or by running this code:

baseDownloadURL = "https://vision.in.tum.de/rgbd/dataset/freiburg3/rgbd_dataset_freiburg3_long_office_household.tgz"; 
dataFolder = fullfile(tempdir,"tum_rgbd_dataset",filesep); 
options = weboptions(Timeout=Inf);
tgzFileName = dataFolder+"fr3_office.tgz";
folderExists = exist(dataFolder,"dir");

% Create a folder in a temporary directory to save the downloaded file
if ~folderExists  
    mkdir(dataFolder) 
    disp("Downloading fr3_office.tgz (1.38 GB). This download can take a few minutes.") 
    websave(tgzFileName,baseDownloadURL,options); 
    
    % Extract contents of the downloaded file
    disp("Extracting fr3_office.tgz (1.38 GB) ...") 
    untar(tgzFileName,dataFolder); 
end

Create two imageDatastore objects. One to store the color images and the other to store the depth images.

colorImageFolder = dataFolder+"rgbd_dataset_freiburg3_long_office_household/rgb/";
depthImageFolder = dataFolder+"rgbd_dataset_freiburg3_long_office_household/depth/";

imdsColor = imageDatastore(colorImageFolder);
imdsDepth = imageDatastore(depthImageFolder);

Select the synchronized pair of color and depth images.

data = load("rgbDepthPairs.mat");
imdsColor=subset(imdsColor, data.indexPairs(:, 1));
imdsDepth=subset(imdsDepth, data.indexPairs(:, 2));

Specify your camera intrinsic parameters, and use them to create an RGB-D visual SLAM object.

intrinsics = cameraIntrinsics([535.4 539.2],[320.1 247.6],[480 640]);
depthScaleFactor = 5000;
vslam = rgbdvslam(intrinsics,depthScaleFactor);

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

for i = 1:numel(imdsColor.Files)
    colorImage = readimage(imdsColor,i);
    depthImage = readimage(imdsDepth,i);
    addFrame(vslam,colorImage,depthImage);

    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 — RGB-D visual SLAM object

rgbdvslam object

RGB-D visual SLAM object, specified as an rgbdvslam object.

Output Arguments

xyzPoints — World point coordinates of 3-D map

M-by-3 matrix

World point coordinates of 3-D map, returned as an M-by-3 matrix. M is the number of points, and each point is of the form [X Y Z].

Version History

Introduced in R2024a