キャリブレートされたカメラによる平面オブジェクトの測定について

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直暉田鴈 on 10 Feb 2023

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https://uk.mathworks.com/matlabcentral/answers/1910010-

Commented: 直暉田鴈 on 11 Feb 2023

現在起こっているエラー：

MATLABで実行するとある一文がエラーになり、実行が遮断されてしまう。

エラー箇所：

camExtrinsics = estimateExtrinsics(imagePoints, worldPoints, camIntrinsics);

エラー内容：

スクリプトestimateExtrinsicsが関数として実行することをサポートされません。

プログラムを1個ずつ実行したり、MATLABが提供しているソースコードをブロックごとにコピー＆ペーストを行ったが変化なし

プログラムのエラー解決をお願いいたします。

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Tohru Kikawada on 10 Feb 2023

どちらのソースコードを実行されてますでしょうか。例題でしたらリンクを貼っていただけると何か分かるかもしれません。

直暉田鴈 on 10 Feb 2023

Moved: Atsushi Ueno on 10 Feb 2023

Open in MATLAB Online

こちらがプログラムの内容になります。

キャリブレーションイメージの準備

numImages = 9;
files = cell(1, numImages);
for i = 1:numImages
    files{i} = fullfile(matlabroot, 'toolbox', 'vision', 'visiondata', ...
        'calibration', 'slr', sprintf('image%d.jpg', i));
end
% Display one of the calibration images
magnification = 25;
I = imread(files{1});
figure; imshow(I, InitialMagnification = magnification);
title("One of the Calibration Images");

カメラパラメータの推定

% Detect the checkerboard corners in the images.
[imagePoints, boardSize] = detectCheckerboardPoints(files);
% Generate the world coordinates of the checkerboard corners in the
% pattern-centric coordinate system, with the upper-left corner at (0,0).
squareSize = 29; % in millimeters
worldPoints = generateCheckerboardPoints(boardSize, squareSize);
% Calibrate the camera.
imageSize = [size(I, 1), size(I, 2)];
cameraParams = estimateCameraParameters(imagePoints, worldPoints, ...
    ImageSize = imageSize);
% Evaluate calibration accuracy.
figure; showReprojectionErrors(cameraParams);
title("Reprojection Errors");

推定するオブジェクトのイメージの読み取り

imOrig = imread(fullfile(matlabroot, "toolbox", "vision", "visiondata", ...
    "calibration", "slr", "image9.jpg"));
figure; imshow(imOrig, InitialMagnification = magnification);
title("Input Image");

イメージの歪み補正

% Since the lens introduced little distortion, use 'full' output view to illustrate that
% the image was undistored. If we used the default 'same' option, it would be difficult
% to notice any difference when compared to the original image. Notice the small black borders.
[im, newOrigin] = undistortImage(imOrig, cameraParams, OutputView = "full");
figure; imshow(im, InitialMagnification = magnification);
title("Undistorted Image");

コインのセグメント化

% Convert the image to the HSV color space.
imHSV = rgb2hsv(im);
% Get the saturation channel.
saturation = imHSV(:, :, 2);
% Threshold the image
t = graythresh(saturation);
imCoin = (saturation > t);
figure; imshow(imCoin, InitialMagnification = magnification);
title("Segmented Coins");

コインの検出

% Find connected components.
blobAnalysis = vision.BlobAnalysis(AreaOutputPort = true,...
    CentroidOutputPort = false,...
    BoundingBoxOutputPort = true,...
    MinimumBlobArea = 200, ExcludeBorderBlobs = true);
[areas, boxes] = step(blobAnalysis, imCoin);
% Sort connected components in descending order by area
[~, idx] = sort(areas, "Descend");
% Get the two largest components.
boxes = double(boxes(idx(1:2), :));
% Reduce the size of the image for display.
scale = magnification / 100;
imDetectedCoins = imresize(im, scale);
% Insert labels for the coins.
imDetectedCoins = insertObjectAnnotation(imDetectedCoins, "rectangle", ...
    scale * boxes, "penny");
figure; imshow(imDetectedCoins);
title("Detected Coins");

外部パラメータの計算（エラー箇所）

% Detect the checkerboard.
[imagePoints, boardSize] = detectCheckerboardPoints(im);
% Adjust the imagePoints so that they are expressed in the coordinate system
% used in the original image, before it was undistorted.  This adjustment
% makes it compatible with the cameraParameters object computed for the original image.
imagePoints = imagePoints + newOrigin; % adds newOrigin to every row of imagePoints
% Extract camera intrinsics.
camIntrinsics = cameraParams.Intrinsics;
% Compute extrinsic parameters of the camera.↓ココ↓
camExtrinsics = estimateExtrinsics(imagePoints, worldPoints, camIntrinsics);

最初のコインの測定

% Adjust upper left corners of bounding boxes for coordinate system shift 
% caused by undistortImage with output view of 'full'. This would not be
% needed if the output was 'same'. The adjustment makes the points compatible
% with the cameraParameters of the original image.
boxes = boxes + [newOrigin, 0, 0]; % zero padding is added for width and height
% Get the top-left and the top-right corners.
box1 = double(boxes(1, :));
imagePoints1 = [box1(1:2); ...
    box1(1) + box1(3), box1(2)];
% Get the world coordinates of the corners            
worldPoints1 = img2world2d(imagePoints1, camExtrinsics, camIntrinsics);
% Compute the diameter of the coin in millimeters.
d = worldPoints1(2, :) - worldPoints1(1, :);
diameterInMillimeters = hypot(d(1), d(2));
fprintf("Measured diameter of one penny = %0.2f mm\n", diameterInMillimeters);

2個目のコインの測定

% Get the top-left and the top-right corners.
box2 = double(boxes(2, :));
imagePoints2 = [box2(1:2); ...
    box2(1) + box2(3), box2(2)];
% Apply the inverse transformation from image to world            
worldPoints2 = img2world2d(imagePoints2, camExtrinsics, camIntrinsics);
% Compute the diameter of the coin in millimeters.
d = worldPoints2(2, :) - worldPoints2(1, :);
diameterInMillimeters = hypot(d(1), d(2));
fprintf("Measured diameter of the other penny = %0.2f mm\n", diameterInMillimeters);

最初のコインまでの距離の測定

% Compute the center of the first coin in the image.
center1_image = box1(1:2) + box1(3:4)/2;
% Convert to world coordinates.
center1_world  = img2world2d(center1_image, camExtrinsics, camIntrinsics);
% Remember to add the 0 z-coordinate.
center1_world = [center1_world 0];
% Compute the distance to the camera.
cameraPose = extr2pose(camExtrinsics);
cameraLocation = cameraPose.Translation;
distanceToCamera = norm(center1_world - cameraLocation);
fprintf("Distance from the camera to the first penny = %0.2f mm\n", ...
    distanceToCamera);