I am trying to develop a c++ program with opencv library on Xcode 9.3, macOS 10.14, using clang. During weeks I've been trying to solve or understand why I am getting an undefined behavior error that sometimes makes my program crash and sometimes not.
I am reading a set of images from different cameras and storing them in a multidimensional array: silC[camera][image]. (images are well stored)
I get this error THREAD 1: EXC_BAD_ACCESS (code=1, address=0x1177c1530) when I do this: currentImage.at(x,y) even the values of currentImage are not the problem nor the image.
I post the code below if there's any chance someone could help me..
vector< vector<Mat> > silC(8,vector<Mat>()); // Store the pbm images separating from different cameras
* I read the images and store them in silC. *
for (int z=0; z < nz; z++) {
for (int y=0; y < ny; y++) {
for (int x=0; x < nx; x++) {
// Current voxel coordinates in the 3D space
float xcoord = x*voxelsize + Ox + voxelsize/2;
float ycoord = y*voxelsize + Oy + voxelsize/2;
float zcoord = z*voxelsize + Oz + voxelsize/2;
for (int camId=0; camId < matricesP.size(); camId++) {
imgId = 0;
currentImage = silC[camId][imgId];
int w = silC[camId][imgId].cols;
int h = silC[camId][imgId].rows;
// Project the voxel from the 3D space to the images
Mat P = matricesP[camId];
Mat projection = P*(Mat_<float>(4,1) << xcoord,ycoord,zcoord,1.0);
//We get the point in homog coord.
float xp = projection.at<float>(0);
float yp = projection.at<float>(1);
float zp = projection.at<float>(2);
// Get the cartesian coord
int xp2d = cvRound(xp/zp);
int yp2d = cvRound(yp/zp);
if(xp2d >= 0 && xp2d < w && yp2d >= 0 && yp2d < h){
// all values are correct! :/
// int value = silC[camId][imgId].at<float>(xp2d, yp2d); // undefined behaviour: crashes sometimes..
int value = currentImage.at<float>(xp2d, yp2d); // undefined behaviour also crashes sometimes..
if(value == 255){
cout << "Voxel okey \n";
}
}
}
}
}
}
EDIT:
The solution posted on comments below is that instead of currentImage.at(xp2d,yp2d) --> currentImage.at(yp2d,xp2d), as cv::Mat access requieres.
BUT, I tried to parallelize the for several times with openMP (#pragma omp parallel for) but it kept crashing. If someone is familiar with parallelize I'll appreciate any help.
the solution is what #rafix07 posted. Thank you very much guys, next time I'll try to focus more.
Related
So I'm trying to modify the Kinect BodyBasicsD2D code so that a fixed number of "target positions" appear on the screen (as ellipses) for the user to move his hand toward. I'm having trouble creating the initial target positions.
This is my code in the header file for the allocation of the array of target positions (these are a public field of the CBodyBasics class, already built into the original BodyToBasics program):
D2D1_POINT_2F* targetPositions = NULL;
int numTargets = 3;
Then I have a function "GenerateTargetPositions" which is supposed to generate 3, in this case, target positions to be passed into the "DrawTargetPositions" function.
void CBodyBasics::GenerateTargetPositions(D2D1_POINT_2F * targetPositions, int numTargets)
{
targetPositions = new D2D1_POINT_2F[numTargets];
RECT rct;
GetClientRect(GetDlgItem(m_hWnd, IDC_VIDEOVIEW), &rct);
int width = rct.right;
int height = rct.bottom;
FLOAT x;
FLOAT y;
D2D1_POINT_2F tempPoint;
for (int i = 0; i < numTargets; i++) {
x = 1.0f*i*width / numTargets;
y = 1.0f*i*height / numTargets;
tempPoint = D2D1::Point2F(x, y);
targetPositions[i] = tempPoint;
}
}
My DrawTargetPositions function is:
void CBodyBasics::DrawTargetPositions(D2D1_POINT_2F * targetPositions, int numTargets)
{
D2D1_ELLIPSE ellipse;
for (int i = 0; i < numTargets; i++)
{
ellipse = D2D1::Ellipse(targetPositions[i], 50.f, 50.f);
m_pRenderTarget->FillEllipse(ellipse, m_pSilverBrush);
}
}
When I try to run my code, I get the error that both "targetPositions" and "targetPositions[i]" is NULL (and thus my GenerateTargetPositions function must not be working properly). I believe that targetPositions[i] is a struct (a point with x and y values) so I am wondering if this may be the reason for my errors.
I call GenerateTargetPositions and DrawTargetPositions before the main "while" loop in my code so that each function is not being called on each iteration (there are many iterations of through the while loop because this is an interactive Microsoft Kinect, recording one's movements).
Any suggestions and advice would be greatly appreciated. Thanks so much!
I am implementing a ray tracing program using VS2015 community. The program fills a screen size color buffer (width * height with element type of Eigen::Vector3f), then save the buffer content to a ppm file.
The basic loop (Note the output section at the end of the outer loop):
using Vec3f = Eigen::Vector3f;
Vec3f * buffer = new Vec3f[w * h];
// for each pixel
for (int y = 0; y < h; y++) for (int x = 0; x < w; x++)
{
int const i = (h - y - 1) * w + x;
buffer[i] = Vec3f::Zero();
// 2x2 subpixel
for (int sy = 0; sy < 2; sy++) for (int sx = 0; sx < 2; sx++)
{
Vec3f r = Vec3f::Zero();
// sampling
for (int s = 0; s < samps; s++)
{
// do some computation and accumulation to r
// r = ...
}
buffer[i] = buffer[i] + r;
}
buffer[i] = buffer[i] * 0.25f;
// debug with an output section
//if (x % 16 == 0 && y % 16 == 0)
// std::cout << buffer[i] << std::endl;
}
I can get proper result with configurations of:
Debug, x86 or x64;
Release, x86;
Release (optimization = \Od), x64.
However, the buffer is all zero vectors with Release (optimization = \O1 or \O2 or \Ox), x64, and what I got is a black picture.
So with Release (optimization = \O1 or \O2 or \Ox), x64, I uncommented the output section to check the values in the buffer. The strange thing is, each pixel that I checked has a correct value, those not checked remains zero vector. For example, if I check every 16 pixels like the upper code, I will get a picture like this (256*256 black tessellated every 16 pixel):
I googled and read some materials like Surviving the Release Version, but still have no idea. Could anyone provide some experiences dealing with these problems?
Update: The code above is not so detailed, full code is here, depends on Eigen 3.2.6.
After going through the code on Ideone, the problem seems to be as follows. In the Scene class, the intersect method returns a bool const &. The returned reference is a local variable. If you examine the Error/Warning logs you'd have seen:
Warning 2 warning C4172: returning address of local variable or temporary ***.cpp 129 1
changing the return type to bool rectifies the problem and the output is similar to that from the 32 bit version.
I'm writing a renderer using low-level SDL functions to learn how it all works. I am now trying to do polygon drawing, but I run into errors possibly due to my inexperience with C++. When running the code I get a munmap_chunk() - Invalid pointer error. Searching reveals that it is most likely due to free()-ing the memory twice. The error happens when returning from the function. I realize that the error comes from automatically free()ing memory which has been automatically free()d before, but I'm not experienced enough with C++ to spot the error. Any clues?
My code:
void DrawPolygon (const vector<vec3> & verts, vec3 color){
// 0. Project to the screen
vector<ivec2> vertices(verts.size());
for(int i = 0; i < verts.size(); i++){
VertexShader(verts.at(i), vertices.at(i));
}
// 1. Find max and min y-value of the polygon
// and compute the number of rows it occupies.
int miny = vertices[0].y;
int maxy = vertices[0].y;
for (int i = 1; i < 3; i++){
if (vertices[i].y < miny){
miny = vertices[i].y;
}
if (vertices[i].y > maxy){
maxy = vertices[i].y;
}
}
int rows = abs(maxy - miny) + 1;
// 2. Resize leftPixels and rightPixels
// so that they have an element for each row.
vector<ivec2> leftPixels(rows);
vector<ivec2> rightPixels(rows);
// 3. Initialize the x-coordinates in leftPixels
// to some really large value and the x-coordinates
// in rightPixels to some really small value.
for(int i = 0; i < rows; i++){
leftPixels[i].x = std::numeric_limits<int>::max();
rightPixels[i].x = std::numeric_limits<int>::min();
leftPixels[i].y = miny + i;
rightPixels[i].y = miny + i;
}
// 4. Loop through all edges of the polygon and use
// linear interpolation to find the x-coordinate for
// each row it occupies. Update the corresponding
// values in rightPixels and leftPixels.
for(int i = 0; i < 3; i++){
ivec2 a = vertices[i];
ivec2 b = vertices[(i+1)%3];
// find the number of pixels to draw
ivec2 delta = glm::abs(a - b);
int pixels = glm::max(delta.x, delta.y) + 1;
// interpolate to find the pixels
vector<ivec2> line (pixels);
Interpolate(a, b, line);
for(int j = 0; j < pixels; j++){
ivec2 p = line[j];
ivec2 cmpl = leftPixels[p.y - miny];
ivec2 cmpr = rightPixels[p.y - miny];
if(p.x < cmpl.x){
leftPixels[p.y - miny].x = p.x;
//leftPixels[p.y - miny] = cmpl;
}
if(p.x > cmpr.x){
rightPixels[p.y - miny].x = p.x;
//cmpr.x = p.x;
//rightPixels[p.y - miny] = cmpr;
}
}
}
for(int i = 0; i < leftPixels.size(); i++){
ivec2 l = leftPixels.at(i);
ivec2 r = rightPixels.at(i);
// y coord the same, iterate over x
int y = l.y;
for(int x = l.x; x <= r.x; x++){
PutPixelSDL(screen, x, y, color);
}
}
}
Using valgrind gives me this output (this is the first error it reports). Weirdly, the program recovers and keeps running with the expected result, apparently not getting the same error again:
==5706== Invalid write of size 4
==5706== at 0x40AD61: DrawPolygon(std::vector<glm::detail::tvec3<float>, std::allocator<glm::detail::tvec3<float> > > const&, glm::detail::tvec3<float>) (in /home/actimia/prog/dgi14/lab3/ThirdLab)
==5706== by 0x409C78: Draw() (in /home/actimia/prog/dgi14/lab3/ThirdLab)
==5706== by 0x409668: main (in /home/actimia/prog/dgi14/lab3/ThirdLab)
I think my previous post on similar topic would be useful.
https://stackoverflow.com/a/22658693/2724703
From your Valgrind report, it look like your program is doing memory corruption due to overflow. This does not seems like "double free" error(this is overflow scenario). You have mentioned that sometime valgrind is not reporting any error this makes this problem more difficult. However there is certainly a memory corruption and you must fix them. Memory error sometime occur intermittent due to various reason(different input parameter, multi-threaded, change of execution sequence).
So, I'm writing (or have written) a contour mapping application for mapping power frequency in North America, and it works really well... On linux. I run it on a loop to update a bmp map file, which I'm eventually going to output on a website. It can run and update itself in about 3 seconds, which is great for me. The problem came when I tried to port the application to windows. I moved the code into Visual Studios 2012. Linked the libraries, compiled and such, I had to make it ignore a few warnings about float to integer conversion, but I got it working.
Then, I had it run, and it didn't seem to do anything. But, after adding a few output commands, I realized it was doing something, it was just doing it probably 100x slower than the Linux executable! I mean, admittedly, the code is pretty intensive (around 400,000 iterations), but this is just ridiculous.
I saw a lot of other topics about VS running slow in debug mode, but even after I compile and run an executable, it's still just as slow.
Here's relevant code, let me know if you have any ideas. Some of the functions you won't recognize because either they aren't relevant to performance (I only call them once, and I know they aren't the source of the speed problem) or they come from the Easy BMP library I'm using for image manipulation. Right now, I have it set to output a 100X100 image, but originally I was outputting a 800x500 pixel image:
float get_value(int x, int y, int dataNum, vector<vector<float> > data)
{
vector<float> distance;
float value=0; float distanceTotal = 0;
for(int i=0; i<dataNum; i++)
{
distance.push_back(sqrt(pow(data[0][i]-x,2) + pow(data[1][i]-y,2)));
if(distance[i] < 2)
return 0;
distance[i] = 1/pow(distance[i],3);
distanceTotal+=distance[i];
}
for(int i=0; i<dataNum; i++)
{
value+=distance[i]/distanceTotal*data[2][i];
}
return value;
}
int _tmain(int argc, _TCHAR* argv[])
{
//set image attributes
int height=100; int width = 100; int colorScale = 5*255; string dataFile = "data2.txt";
//get data and colormap
vector<vector<float> > data = getData(dataFile, width, height);
vector<RGBApixel> colorMap = makeColorMap(colorScale);
int dataNum = data[0].size();
pair<float,float> range = make_pair(*min_element(data[2].begin(),data[2].end()),*max_element(data[2].begin(),data[2].end()));
//make image
BMP newMap;
newMap.SetBitDepth(16);
newMap.SetSize(width,height);
for(int x=0; x<width; x++)
{
for(int y=0; y<height; y++)
{
//for debug purposes
cout << x << " " << y << endl;
float value = get_value(x,y,dataNum,data);
//get color value based on data value
int colorValue = floor((value-range.first)/(range.second-range.first)*colorScale);
//handle border cases
if(colorValue < 0 )
colorValue=0;
else if(colorValue > colorScale-1)
colorValue=colorScale-1;
newMap.SetPixel(x,y,colorMap[colorValue]);
}
}
newMap.WriteToFile("map.bmp");
return 0;
}
Any thoughts?
Thanks!
I am trying to take the imageData of image in this where w= width of image and h = height of image
for (int i = x; i < x+h; i++) //height of frame pixels
{
for (int j = y; j < y+w; j++)//width of frame pixels
{
int pos = i * w * Channels + j; //channels is 3 as rgb
// if any data exists
if (data->imageData[pos]>0) //Taking data (here is the problem how to take)
{
xPos += j;
yPos += i;
nPix++;
}
}
}
jeff7 gives you a link to a very old version of OpenCV. OpenCV 2.0 has a new C++ wrapper that is much better than the C++ wrapper mentioned in the link. I recommend that you read the C++ reference of OpenCV for information on how to access individual pixels.
Another thing to note is: you should have the outer loop being the loop in y-direction (vertical) and the inner loop be the loop in x-direction. OpenCV is in C/C++ and it stores the values in row major.
See good explanation here on multiple methods for accessing pixels in an IplImage in OpenCV.
From the code you've posted your problem lies in your position variable, you'd want something like int pos = i*w*Channels + j*Channels, then you can access the RGB pixels at
unsigned char r = data->imageData[pos];
unsigned char g = data->imageData[pos+1];
unsigned char b = data->imageData[pos+2];
(assuming RGB, but on some platforms I think it can be stored BGR).
uchar* colorImgPtr;
for(int i=0; i<colorImg->width; i++){
for(int j=0; j<colorImg->height; j++){
colorImgPtr = (uchar *)(colorImg->imageData) + (j*colorImg->widthStep + i-colorImg->nChannels)
for(int channel = 0; channel < colorImg->nChannels; channel++){
//colorImgPtr[channel] here you have each value for each pixel for each channel
}
}
}
There are quite a few methods to do this (the link provided by jeff7 is very useful).
My preferred method to access image data is the cvPtr2D method. You'll want something like:
for(int x = 0; x < width; ++x)
{
for(int y = 0; y < height; ++y)
{
uchar* ptr = cvPtr2D(img, y, x, NULL);
// blue channel can now be accessed with ptr[0]
// green channel can now be accessed with ptr[1]
// red channel can now be accessed with ptr[2]
}
}
(img is an IplImage* in the above code)
Not sure if this is the most efficient way of doing this etc. but I find it the easiest and simplest way of doing it.
You can find documentation for this method here.