Malloc Error: OpenCV/C++ while push_back Vector

Question

I try to create a Descriptor using FAST for the Point detection and SIFT for building the Descriptor. For that purpose I use OpenCV. While I use OpenCV's FAST I just use parts of the SIFT code, because I only need the Descriptor. Now I have a really nasty malloc Error and I don't know, how to solve it. I posted my code into GitHub because it is big and I dont really know where the Error comes from. I just know, that it is created at the end of the DO-WHILE-Loop:

    features2d.push_back(features);
    features.clear();
    candidates2d.push_back(candidates);
    candidates.clear();
    }
}while(candidates.size() > 100);

As you can see in the code of GitHub I already tried to release Memory of the Application. Xcode Analysis says, that my Application uses 9 Mb memory. I tried to debug the Error but It was very complicated and I haven't found any clue where the Error comes from.

EDIT I wondered if this Error could occur because I try to access the Image Pixel Value passed to calcOrientationHist(...) with img.at<sift_wt>(...) where typdef float sift_wt at Line 56, and 57 in my code, because normally the Patch I pass outputs the type 0 which means it is a CV_8UC1 But well, I copied this part from the sift.cpp at Line 330 and 331 Normally the SIFT Descriptor should also have a Grayscale image or not?

EDIT2 After changing the type in the img.at<sift_wt>(...)Position nothing changed. So I googled Solutions and landed at the GuardMalloc feature from XCode. Enabling it showed me a new Error which is probably the Reason I get the Malloc Error. In line 77 of my Code. The Error it gives me at this line is EXC_BAD_ACCESS (Code=1, address=....) There are the following lines:

for( k = 0; k < len; k ++){
    int bin = cvRound((n/360.f)+Ori[k]);
    if(bin >= n)
        bin -=n;
    if(bin < 0 )
        bin +=n;
    temphist[bin] += W[k]*Mag[k];
}

The Values of the mentioned Variables are the following: bin = 52, len = 169, n = 36, k = 0, W, Mag, Ori and temphist are not shown.

Here the GuadMalloc Output (sorry but I dont really understand what exactly it wants)

GuardMalloc[Test-1935]: Allocations will be placed on 16 byte boundaries.
GuardMalloc[Test-1935]:  - Some buffer overruns may not be noticed.
GuardMalloc[Test-1935]:  - Applications using vector instructions (e.g., SSE) should work.
GuardMalloc[Test-1935]: version 108
Test(1935,0x102524000) malloc: protecting edges
Test(1935,0x102524000) malloc: enabling scribbling to detect mods to free blocks

Marcel T · Accepted Answer · 2016-09-29 12:22:17Z

1

Answer is simpler as thought... The Problem was, that in the calculation of Bin in the For-loop the wrong value came out. Instead of adding ori[k] it should be a multiplication with ori[k]. The mistake there resulted in a bin value of 52. But the Length of the Array that temphist is pointing to is 38.

For all who have similar Errors I really recomment to use GuardMalloc or Valgrind to debug Malloc Errors.

answered Sep 29, 2016 at 12:22

Marcel T

6571 gold badge7 silver badges29 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Malloc Error: OpenCV/C++ while push_back Vector

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related