There is a problem running minibatchqueue function.

I'm lerning yolo v3 with https://ww2.mathworks.cn/help/vision/ug/object-detection-using-yolo-v3-deep-learning.html?searchHighlight=YOLO&s_tid=srchtitle.

I made my data set. Here is a part of it.

I run my dataset and an error occurs at this step.

mbqTrain = minibatchqueue(preprocessedTrainingData, 2,...

"MiniBatchSize", miniBatchSize,...

"MiniBatchFcn", @(images, boxes, labels) createBatchData(images, boxes, labels, classNames), ...

"MiniBatchFormat", ["SSCB", ""],...

"DispatchInBackground", dispatchInBackground,...

"OutputCast", ["", "double"]);

It says: Error using minibatchqueue, Unable to apply function specified by 'MiniBatchFcn' value.

Caused by: Error using cat, Dimensions of arrays being concatenated are not consistent.

I checked and found that when running the function createBatchData:

function [XTrain, YTrain] = createBatchData(data, groundTruthBoxes, groundTruthClasses, classNames)

some of the data in the input argumentsr groundTruthBoxes become empty. LIke the third line:

But it's supposed to have a 3*4double data here. But it just disappear.

I dont know whether other people have met this question, or it just me. But I'm really frustrated with this question.

Please help me.

Answer 1

[泽宇 王]

I figured out what was the problem. After my step-by-step debugging, I found problem in this line of code.

preprocessedTrainingData = transform(augmentedTrainingData, @(data)preprocess(yolov3Detector, data));

data = read(preprocessedTrainingData);

This line of code points to this function: vision.internal.cnn.LetterBoxImage

function [Inew,bboxnew] = LetterBoxImage(I,targetSize,varargin):

[Irow,Icol,Ichannels] = size(I);

bboxnew = [];

% Compute aspect Ratio.

arI = Irow./Icol;

% Preserve the maximum dimension based on the aspect ratio.

if arI<1

IcolFin = targetSize(1,2);

IrowFin = floor(IcolFin.*arI);

else

IrowFin = targetSize(1,1);

IcolFin = floor(IrowFin./arI);

end

% Resize the input image.

Itmp = imresize(I,[IrowFin,IcolFin]);

% Initialize Inew with gray values.

Inew = ones([targetSize,Ichannels],'like',I).*0.5;

% Compute the offset.

if arI<1

buff = targetSize(1,1)-IrowFin;

else

buff = targetSize(1,2)-IcolFin;

end

% Place the resized image on the canvas image.

if (buff==0)

Inew = Itmp;

else

buffVal = floor(buff/2);

if arI<1

Inew(buffVal:buffVal+IrowFin-1,:,:) = Itmp;

if ~isempty(varargin)

% Resize bounding boxes.

bboxnew = iScaleBboxes(varargin{1,1},size(Itmp),size(I));

bboxnew(:,2) = bboxnew(:,2)+buffVal;

end

else

Inew(:,buffVal:buffVal+IcolFin-1,:) = Itmp;

if ~isempty(varargin)

% Resize bounding boxes.

bboxnew = iScaleBboxes(varargin{1,1},size(Itmp),size(I));

bboxnew(:,1) = bboxnew(:,1)+buffVal;

end

end

end

end

I find the picture which gets error has the size with 612*612*3, and the target size is 227*227*3. So the variable arI goes to 1, and the varible buff goes to 0. The calculation of bboxnew has been skipped, so it goes to [].

[bipun manpati]

hi there,

I would like to know if this error is due to the same size of width and height of the image. as you have mentioned the image size is 612. i had checked in vehicle dataset and found that it has different size of width and height. For my case, image size is 256*256* 3 and found all bounding boxes empty.