I wanted to make a servomotor oscilate between 0-90 degrees when i push a button, but when i push another one, it stops oscillating and then remains in its latest position.
i started with this:
#include <Servo.h>
Servo myservo;
int pos = 0;
const int button1 = 5;
const int button2 = 6;
int lastpos = pos;
void setup() {
myservo.attach(3);
pinMode(button1, INPUT);
pinMode(button2, INPUT);
}
void loop() {
if(digitalRead(button1) == HIGH)
{for(pos = 0; pos <= 90; pos += 1)
{myservo.write(pos);
for(pos = 90; pos >= 0; pos -= 1)
{myservo.write(pos);
delay(36);
} } if(digitalRead(button2) == HIGH){ myservo.write(lastpos);}}}
To start, take a look at how to format code inside a question. It makes it a lot easier to read and help you out. See below for how I formatted for the site, but also readability.
Servo myservo;
int pos = 0;
const int button1 = 5;
const int button2 = 6;
int lastpos = pos;
void setup() {
myservo.attach(3);
pinMode(button1, INPUT);
pinMode(button2, INPUT);
}
void loop() {
if(digitalRead(button1) == HIGH) {
for(pos = 0; pos <= 90; pos += 1) {
myservo.write(pos);
for(pos = 90; pos >= 0; pos -= 1) {
myservo.write(pos);
delay(36);
}
}
if(digitalRead(button2) == HIGH) {
myservo.write(lastpos);
}
}
}
There are several issues with your code based on your description of what you are trying to achieve. First, let's start with the button presses. You are ready the button state, but your code will only detect the button if it is pressed at the exact moment you are doing the digital read. Here's a good resource for reading up on how to properly implement buttons on Arduino: https://www.logiqbit.com/perfect-arduino-button-presses
The second objective is to have the servo sweep back and forth, but stop when you press a button. Your for loops won't let that happen. As currently written, you will always do a sweep to one end and back and then check the next button.
You should update the position of the servo once each time through the loop so you can check on the status of the buttons. In pseudo-code, what I suggest you do is:
void loop() {
//Check button statuses
if(button1), start sweep
if(button2), stop sweep
//Update sweep position
if(ascending && pos < 90) {
//You should be increasing in angle and you haven't reached 90 yet
ascending = TRUE;
pos += 1
myservo.write(pos);
delay(36); //Or whatever delay you need for the servo
} else if(pos > 0) {
//You already reached 90 and are coming back down to 0
ascending = FALSE;
pos -= 1;
delay(36);
}
I am trying to write a simple nonogram solver, in a kind of bruteforce way, but I am stuck on a relatively easy task. Let's say I have a row with clues [2,3] that has a length of 10
so the solutions are:
$$-$$$----
$$--$$$---
$$---$$$--
$$----$$$-
$$-----$$$
-$$----$$$
--$$---$$$
---$$--$$$
----$$-$$$
-$$---$$$-
--$$-$$$--
I want to find all the possible solutions for a row
I know that I have to consider each block separately, and each block will have an availible space of n-(sum of remaining blocks length + number of remaining blocks) but I do not know how to progress from here
Well, this question already have a good answer, so think of this one more as an advertisement of python's prowess.
def place(blocks,total):
if not blocks: return ["-"*total]
if blocks[0]>total: return []
starts = total-blocks[0] #starts = 2 means possible starting indexes are [0,1,2]
if len(blocks)==1: #this is special case
return [("-"*i+"$"*blocks[0]+"-"*(starts-i)) for i in range(starts+1)]
ans = []
for i in range(total-blocks[0]): #append current solutions
for sol in place(blocks[1:],starts-i-1): #with all possible other solutiona
ans.append("-"*i+"$"*blocks[0]+"-"+sol)
return ans
To test it:
for i in place([2,3,2],12):
print(i)
Which produces output like:
$$-$$$-$$---
$$-$$$--$$--
$$-$$$---$$-
$$-$$$----$$
$$--$$$-$$--
$$--$$$--$$-
$$--$$$---$$
$$---$$$-$$-
$$---$$$--$$
$$----$$$-$$
-$$-$$$-$$--
-$$-$$$--$$-
-$$-$$$---$$
-$$--$$$-$$-
-$$--$$$--$$
-$$---$$$-$$
--$$-$$$-$$-
--$$-$$$--$$
--$$--$$$-$$
---$$-$$$-$$
This is what i got:
#include <iostream>
#include <vector>
#include <string>
using namespace std;
typedef std::vector<bool> tRow;
void printRow(tRow row){
for (bool i : row){
std::cout << ((i) ? '$' : '-');
}
std::cout << std::endl;
}
int requiredCells(const std::vector<int> nums){
int sum = 0;
for (int i : nums){
sum += (i + 1); // The number + the at-least-one-cell gap at is right
}
return (sum == 0) ? 0 : sum - 1; // The right-most number don't need any gap
}
bool appendRow(tRow init, const std::vector<int> pendingNums, unsigned int rowSize, std::vector<tRow> &comb){
if (pendingNums.size() <= 0){
comb.push_back(init);
return false;
}
int cellsRequired = requiredCells(pendingNums);
if (cellsRequired > rowSize){
return false; // There are no combinations
}
tRow prefix;
int gapSize = 0;
std::vector<int> pNumsAux = pendingNums;
pNumsAux.erase(pNumsAux.begin());
unsigned int space = rowSize;
while ((gapSize + cellsRequired) <= rowSize){
space = rowSize;
space -= gapSize;
prefix.clear();
prefix = init;
for (int i = 0; i < gapSize; ++i){
prefix.push_back(false);
}
for (int i = 0; i < pendingNums[0]; ++i){
prefix.push_back(true);
space--;
}
if (space > 0){
prefix.push_back(false);
space--;
}
appendRow(prefix, pNumsAux, space, comb);
++gapSize;
}
return true;
}
std::vector<tRow> getCombinations(const std::vector<int> row, unsigned int rowSize) {
std::vector<tRow> comb;
tRow init;
appendRow(init, row, rowSize, comb);
return comb;
}
int main(){
std::vector<int> row = { 2, 3 };
auto ret = getCombinations(row, 10);
for (tRow r : ret){
while (r.size() < 10)
r.push_back(false);
printRow(r);
}
return 0;
}
And my output is:
$$-$$$----
$$--$$$---
$$---$$$--
$$----$$$--
$$-----$$$
-$$-$$$----
-$$--$$$--
-$$---$$$-
-$$----$$$-
--$$-$$$--
--$$--$$$-
--$$---$$$
---$$-$$$-
---$$--$$$
----$$-$$$
For sure, this must be absolutely improvable.
Note: i did't test it more than already written case
Hope it works for you
Im trying to add settings to a snake game made in processing. I want to have something like easy, normal and hard or something along the lines of that and change the speed and maybe size of the grid. If anyone coudl explain how to id greatly appreciate it!
ArrayList<Integer> x = new ArrayList<Integer>(), y = new ArrayList<Integer>();
int w = 30, h = 30, bs = 20, dir = 2, applex = 12, appley = 10;
int[] dx = {0,0,1,-1}, dy = {1,-1,0,0};
boolean gameover = false;
void setup() {
size(600,600);
x.add(5);
y.add(5);
}
void draw() {
background(255);
for(int i = 0 ; i < w; i++) line(i*bs, 0, i*bs, height); //Vertical line for grid
for(int i = 0 ; i < h; i++) line(0, i*bs, width, i*bs); //Horizontal line for grid
for(int i = 0 ; i < x.size(); i++) {
fill (0,255,0);
rect(x.get(i)*bs, y.get(i)*bs, bs, bs);
}
if(!gameover) {
fill(255,0,0);
rect(applex*bs, appley*bs, bs, bs);
if(frameCount%5==0) {
x.add(0,x.get(0) + dx[dir]);
y.add(0,y.get(0) + dy[dir]);
if(x.get(0) < 0 || y.get(0) < 0 || x.get(0) >= w || y.get(0) >= h) gameover = true;
for(int i = 1; i < x.size(); i++) if(x.get(0) == x.get(i) && y.get(0) == y.get(i)) gameover = true;
if(x.get(0)==applex && y.get(0)==appley) {
applex = (int)random(0,w);
appley = (int)random(0,h);
}else {
x.remove(x.size()-1);
y.remove(y.size()-1);
}
}
} else {
fill(0);
textSize(30);
text("GAME OVER. Press Space to Play Again", 20, height/2);
if(keyPressed && key == ' ') {
x.clear(); //Clear array list
y.clear(); //Clear array list
x.add(5);
y.add(5);
gameover = false;
}
}
if (keyPressed == true) {
int newdir = key=='s' ? 0 : (key=='w' ? 1 : (key=='d' ? 2 : (key=='a' ? 3 : -1)));
if(newdir != -1 && (x.size() <= 1 || !(x.get(1) ==x.get(0) + dx[newdir] && y.get (1) == y.get(0) + dy[newdir]))) dir = newdir;
}
}
You need to break your problem down into smaller steps:
Step one: Can you store the difficulty in a variable? This might be an int that keeps track of a level, or a boolean that switches between easy and hard. Just hardcode the value of that variable for now.
Step two: Can you write your code so it changes behavior based on the difficulty level? Use the variable you created in step one. You might use an if statement to check the difficulty level, or maybe the speed increases over time. It's completely up to you. Start out with a hard-coded value. Change the value to see different behaviors.
Step three: Can you programatically change that value? Maybe this requires a settings screen where the user chooses the difficulty, or maybe it gets more difficult over time. But you have to do the first two steps before you can start this step.
If you get stuck on a specific step, then post an MCVE and we'll go from there.
I want to parallelize an OpenMP raytracing algorithm that contains two for loops.
Is there anything more I can do than just setting omp_set_num_threads(omp_get_max_threads()) and putting #pragma omp parallel for in front of the first for loop?
So far I've reached a 2.13-times faster algorithm.
Code:
start = omp_get_wtime();
#pragma omp parallel for
for (int i = 0; i < (viewport.xvmax - viewport.xvmin); i++)
{
for (int j = 0; j < (viewport.yvmax - viewport.yvmin); j++)
{
int intersection_object = -1; // none
int reflected_intersection_object = -1; // none
double current_lambda = 0x7fefffffffffffff; // maximum positive double
double current_reflected_lambda = 0x7fefffffffffffff; // maximum positive double
RAY ray, shadow_ray, reflected_ray;
PIXEL pixel;
SPHERE_INTERSECTION intersection, current_intersection, shadow_ray_intersection, reflected_ray_intersection, current_reflected_intersection;
double red, green, blue;
double theta, reflected_theta;
bool bShadow = false;
pixel.i = i;
pixel.j = j;
// 1. compute ray:
compute_ray(&ray, &view_point, &viewport, &pixel, &camera_frame, focal_distance);
// 2. check if ray hits an object:
for (int k = 0; k < NSPHERES; k++)
{
if (sphere_intersection(&ray, &sphere[k], &intersection))
{
// there is an intersection between ray and object
// 1. Izracunanaj normalu...
intersection_normal(&sphere[k], &intersection, &ray);
// 2. ako je lambda presjecista manji od trenutacnog:
if (intersection.lambda_in < current_lambda)
{
current_lambda = intersection.lambda_in;
intersection_object = k;
copy_intersection_struct(¤t_intersection, &intersection);
}
// izracunaj current lambda current_lambda =
// oznaci koji je trenutacni object : intersection_object =
// kopiraj strukturu presjeka : copy_intersection_struct();
}
}
// Compute the color of the pixel:
if (intersection_object > -1)
{
compute_shadow_ray(&shadow_ray, &intersection, &light);
theta = dotproduct(&(shadow_ray.direction), &(intersection.normal));
for (int l = 0; l<NSPHERES; l++)
{
if (l != intersection_object)
{
if (sphere_intersection(&shadow_ray, &sphere[l], &shadow_ray_intersection) && (theta>0.0))
bShadow = true;
}
}
if (bShadow)
{ // if in shadow, add only ambiental light to the surface color
red = shadow(sphere[intersection_object].ka_rgb[CRED], ambi_light_intensity);
green = shadow(sphere[intersection_object].ka_rgb[CGREEN], ambi_light_intensity);
blue = shadow(sphere[intersection_object].ka_rgb[CBLUE], ambi_light_intensity);
}
else
{
// the intersection is not in shadow:
red = blinnphong_shading(¤t_intersection, &light, &view_point,
sphere[intersection_object].kd_rgb[CRED], sphere[intersection_object].ks_rgb[CRED], sphere[intersection_object].ka_rgb[CRED], sphere[intersection_object].shininess,
light_intensity, ambi_light_intensity);
green = blinnphong_shading(¤t_intersection, &light, &view_point,
sphere[intersection_object].kd_rgb[CGREEN], sphere[intersection_object].ks_rgb[CGREEN], sphere[intersection_object].ka_rgb[CGREEN], sphere[intersection_object].shininess,
light_intensity, ambi_light_intensity);
blue = blinnphong_shading(¤t_intersection, &light, &view_point,
sphere[intersection_object].kd_rgb[CBLUE], sphere[intersection_object].ks_rgb[CBLUE], sphere[intersection_object].ka_rgb[CBLUE], sphere[intersection_object].shininess,
light_intensity, ambi_light_intensity);
}
tabelaPixlov[i][j].red = red;
tabelaPixlov[i][j].green = green;
tabelaPixlov[i][j].blue = blue;
glColor3f(tabelaPixlov[i][j].red, tabelaPixlov[i][j].green, tabelaPixlov[i][j].blue);
intersection_object = -1;
bShadow = false;
}
else
{
// draw the pixel with the background color
tabelaPixlov[i][j].red = 0;
tabelaPixlov[i][j].green = 0;
tabelaPixlov[i][j].blue = 0;
intersection_object = -1;
bShadow = false;
}
current_lambda = 0x7fefffffffffffff;
current_reflected_lambda = 0x7fefffffffffffff;
}
}
//glFlush();
stop = omp_get_wtime();
for (int i = 0; i < (viewport.xvmax - viewport.xvmin); i++)
{
for (int j = 0; j < (viewport.yvmax - viewport.yvmin); j++)
{
glColor3f(tabelaPixlov[i][j].red, tabelaPixlov[i][j].green, tabelaPixlov[i][j].blue);
glBegin(GL_POINTS);
glVertex2i(i, j);
glEnd();
}
}
printf("%f\n št niti:%d\n", stop - start, omp_get_max_threads());
glutSwapBuffers();
}
With ray tracing you should use schedule(dynamic). Besides that I would suggest fusing the loop
#pragma omp parallel for schedule(dynamic) {
for(int n=0; n<((viewport.xvmax - viewport.xvmin)*(viewport.yvmax - viewport.yvmin); n++) {
int i = n/(viewport.yvmax - viewport.yvmin);
int j = n%(viewport.yvmax - viewport.yvmin)
//...
}
Also, why are you setting the number of threads? Just use the default which should be set to the number of logical cores. If you have Hyper Threading ray tracing is one of the algorithms that will benefit from Hyper Threading so you don't want to set the number of threads to the number of physical cores.
In addition to using MIMD with OpenMP I would suggest looking into using SIMD for ray tracing. See Ingo Wald's PhD thesis for an example on how to do this http://www.sci.utah.edu/~wald/PhD/. Basically you shoot four (eight) rays in one SSE (AVX) register and then go down the ray tree for each ray in parallel. However, if one ray finishes you hold it and wait until all four are finished (this is similar to what is done on the GPU). There have been many papers written since which have more advanced tricks based on this idea.
Does anybody know how to find the local maxima in a grayscale IPL_DEPTH_8U image using OpenCV? HarrisCorner mentions something like that but I'm actually not interested in corners ...
Thanks!
A pixel is considered a local maximum if it is equal to the maximum value in a 'local' neighborhood. The function below captures this property in two lines of code.
To deal with pixels on 'plateaus' (value equal to their neighborhood) one can use the local minimum property, since plateaus pixels are equal to their local minimum. The rest of the code filters out those pixels.
void non_maxima_suppression(const cv::Mat& image, cv::Mat& mask, bool remove_plateaus) {
// find pixels that are equal to the local neighborhood not maximum (including 'plateaus')
cv::dilate(image, mask, cv::Mat());
cv::compare(image, mask, mask, cv::CMP_GE);
// optionally filter out pixels that are equal to the local minimum ('plateaus')
if (remove_plateaus) {
cv::Mat non_plateau_mask;
cv::erode(image, non_plateau_mask, cv::Mat());
cv::compare(image, non_plateau_mask, non_plateau_mask, cv::CMP_GT);
cv::bitwise_and(mask, non_plateau_mask, mask);
}
}
Here's a simple trick. The idea is to dilate with a kernel that contains a hole in the center. After the dilate operation, each pixel is replaced with the maximum of it's neighbors (using a 5 by 5 neighborhood in this example), excluding the original pixel.
Mat1b kernelLM(Size(5, 5), 1u);
kernelLM.at<uchar>(2, 2) = 0u;
Mat imageLM;
dilate(image, imageLM, kernelLM);
Mat1b localMaxima = (image > imageLM);
Actually after I posted the code above I wrote a better and very very faster one ..
The code above suffers even for a 640x480 picture..
I optimized it and now it is very very fast even for 1600x1200 pic.
Here is the code :
void localMaxima(cv::Mat src,cv::Mat &dst,int squareSize)
{
if (squareSize==0)
{
dst = src.clone();
return;
}
Mat m0;
dst = src.clone();
Point maxLoc(0,0);
//1.Be sure to have at least 3x3 for at least looking at 1 pixel close neighbours
// Also the window must be <odd>x<odd>
SANITYCHECK(squareSize,3,1);
int sqrCenter = (squareSize-1)/2;
//2.Create the localWindow mask to get things done faster
// When we find a local maxima we will multiply the subwindow with this MASK
// So that we will not search for those 0 values again and again
Mat localWindowMask = Mat::zeros(Size(squareSize,squareSize),CV_8U);//boolean
localWindowMask.at<unsigned char>(sqrCenter,sqrCenter)=1;
//3.Find the threshold value to threshold the image
//this function here returns the peak of histogram of picture
//the picture is a thresholded picture it will have a lot of zero values in it
//so that the second boolean variable says :
// (boolean) ? "return peak even if it is at 0" : "return peak discarding 0"
int thrshld = maxUsedValInHistogramData(dst,false);
threshold(dst,m0,thrshld,1,THRESH_BINARY);
//4.Now delete all thresholded values from picture
dst = dst.mul(m0);
//put the src in the middle of the big array
for (int row=sqrCenter;row<dst.size().height-sqrCenter;row++)
for (int col=sqrCenter;col<dst.size().width-sqrCenter;col++)
{
//1.if the value is zero it can not be a local maxima
if (dst.at<unsigned char>(row,col)==0)
continue;
//2.the value at (row,col) is not 0 so it can be a local maxima point
m0 = dst.colRange(col-sqrCenter,col+sqrCenter+1).rowRange(row-sqrCenter,row+sqrCenter+1);
minMaxLoc(m0,NULL,NULL,NULL,&maxLoc);
//if the maximum location of this subWindow is at center
//it means we found the local maxima
//so we should delete the surrounding values which lies in the subWindow area
//hence we will not try to find if a point is at localMaxima when already found a neighbour was
if ((maxLoc.x==sqrCenter)&&(maxLoc.y==sqrCenter))
{
m0 = m0.mul(localWindowMask);
//we can skip the values that we already made 0 by the above function
col+=sqrCenter;
}
}
}
The following listing is a function similar to Matlab's "imregionalmax". It looks for at most nLocMax local maxima above threshold, where the found local maxima are at least minDistBtwLocMax pixels apart. It returns the actual number of local maxima found. Notice that it uses OpenCV's minMaxLoc to find global maxima. It is "opencv-self-contained" except for the (easy to implement) function vdist, which computes the (euclidian) distance between points (r,c) and (row,col).
input is one-channel CV_32F matrix, and locations is nLocMax (rows) by 2 (columns) CV_32S matrix.
int imregionalmax(Mat input, int nLocMax, float threshold, float minDistBtwLocMax, Mat locations)
{
Mat scratch = input.clone();
int nFoundLocMax = 0;
for (int i = 0; i < nLocMax; i++) {
Point location;
double maxVal;
minMaxLoc(scratch, NULL, &maxVal, NULL, &location);
if (maxVal > threshold) {
nFoundLocMax += 1;
int row = location.y;
int col = location.x;
locations.at<int>(i,0) = row;
locations.at<int>(i,1) = col;
int r0 = (row-minDistBtwLocMax > -1 ? row-minDistBtwLocMax : 0);
int r1 = (row+minDistBtwLocMax < scratch.rows ? row+minDistBtwLocMax : scratch.rows-1);
int c0 = (col-minDistBtwLocMax > -1 ? col-minDistBtwLocMax : 0);
int c1 = (col+minDistBtwLocMax < scratch.cols ? col+minDistBtwLocMax : scratch.cols-1);
for (int r = r0; r <= r1; r++) {
for (int c = c0; c <= c1; c++) {
if (vdist(Point2DMake(r, c),Point2DMake(row, col)) <= minDistBtwLocMax) {
scratch.at<float>(r,c) = 0.0;
}
}
}
} else {
break;
}
}
return nFoundLocMax;
}
The first question to answer would be what is "local" in your opinion. The answer may well be a square window (say 3x3 or 5x5) or circular window of a certain radius. You can then scan over the entire image with the window centered at each pixel and pick the highest value in the window.
See this for how to access pixel values in OpenCV.
This is very fast method. It stored founded maxima in a vector of
Points.
vector <Point> GetLocalMaxima(const cv::Mat Src,int MatchingSize, int Threshold, int GaussKernel )
{
vector <Point> vMaxLoc(0);
if ((MatchingSize % 2 == 0) || (GaussKernel % 2 == 0)) // MatchingSize and GaussKernel have to be "odd" and > 0
{
return vMaxLoc;
}
vMaxLoc.reserve(100); // Reserve place for fast access
Mat ProcessImg = Src.clone();
int W = Src.cols;
int H = Src.rows;
int SearchWidth = W - MatchingSize;
int SearchHeight = H - MatchingSize;
int MatchingSquareCenter = MatchingSize/2;
if(GaussKernel > 1) // If You need a smoothing
{
GaussianBlur(ProcessImg,ProcessImg,Size(GaussKernel,GaussKernel),0,0,4);
}
uchar* pProcess = (uchar *) ProcessImg.data; // The pointer to image Data
int Shift = MatchingSquareCenter * ( W + 1);
int k = 0;
for(int y=0; y < SearchHeight; ++y)
{
int m = k + Shift;
for(int x=0;x < SearchWidth ; ++x)
{
if (pProcess[m++] >= Threshold)
{
Point LocMax;
Mat mROI(ProcessImg, Rect(x,y,MatchingSize,MatchingSize));
minMaxLoc(mROI,NULL,NULL,NULL,&LocMax);
if (LocMax.x == MatchingSquareCenter && LocMax.y == MatchingSquareCenter)
{
vMaxLoc.push_back(Point( x+LocMax.x,y + LocMax.y ));
// imshow("W1",mROI);cvWaitKey(0); //For gebug
}
}
}
k += W;
}
return vMaxLoc;
}
Found a simple solution.
In this example, if you are trying to find 2 results of a matchTemplate function with a minimum distance from each other.
cv::Mat result;
matchTemplate(search, target, result, CV_TM_SQDIFF_NORMED);
float score1;
cv::Point displacement1 = MinMax(result, score1);
cv::circle(result, cv::Point(displacement1.x+result.cols/2 , displacement1.y+result.rows/2), 10, cv::Scalar(0), CV_FILLED, 8, 0);
float score2;
cv::Point displacement2 = MinMax(result, score2);
where
cv::Point MinMax(cv::Mat &result, float &score)
{
double minVal, maxVal;
cv::Point minLoc, maxLoc, matchLoc;
minMaxLoc(result, &minVal, &maxVal, &minLoc, &maxLoc, cv::Mat());
matchLoc.x = minLoc.x - result.cols/2;
matchLoc.y = minLoc.y - result.rows/2;
return minVal;
}
The process is:
Find global Minimum using minMaxLoc
Draw a filled white circle around global minimum using min distance between minima as radius
Find another minimum
The the scores can be compared to each other to determine, for example, the certainty of the match,
To find more than just the global minimum and maximum try using this function from skimage:
http://scikit-image.org/docs/dev/api/skimage.feature.html#skimage.feature.peak_local_max
You can parameterize the minimum distance between peaks, too. And more. To find minima, use negated values (take care of the array type though, 255-image could do the trick).
You can go over each pixel and test if it is a local maxima. Here is how I would do it.
The input is assumed to be type CV_32FC1
#include <vector>//std::vector
#include <algorithm>//std::sort
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/core/core.hpp"
//structure for maximal values including position
struct SRegionalMaxPoint
{
SRegionalMaxPoint():
values(-FLT_MAX),
row(-1),
col(-1)
{}
float values;
int row;
int col;
//ascending order
bool operator()(const SRegionalMaxPoint& a, const SRegionalMaxPoint& b)
{
return a.values < b.values;
}
};
//checks if pixel is local max
bool isRegionalMax(const float* im_ptr, const int& cols )
{
float center = *im_ptr;
bool is_regional_max = true;
im_ptr -= (cols + 1);
for (int ii = 0; ii < 3; ++ii, im_ptr+= (cols-3))
{
for (int jj = 0; jj < 3; ++jj, im_ptr++)
{
if (ii != 1 || jj != 1)
{
is_regional_max &= (center > *im_ptr);
}
}
}
return is_regional_max;
}
void imregionalmax(
const cv::Mat& input,
std::vector<SRegionalMaxPoint>& buffer)
{
//find local max - top maxima
static const int margin = 1;
const int rows = input.rows;
const int cols = input.cols;
for (int i = margin; i < rows - margin; ++i)
{
const float* im_ptr = input.ptr<float>(i, margin);
for (int j = margin; j < cols - margin; ++j, im_ptr++)
{
//Check if pixel is local maximum
if ( isRegionalMax(im_ptr, cols ) )
{
cv::Rect roi = cv::Rect(j - margin, i - margin, 3, 3);
cv::Mat subMat = input(roi);
float val = *im_ptr;
//replace smallest value in buffer
if ( val > buffer[0].values )
{
buffer[0].values = val;
buffer[0].row = i;
buffer[0].col = j;
std::sort(buffer.begin(), buffer.end(), SRegionalMaxPoint());
}
}
}
}
}
For testing the code you can try this:
cv::Mat temp = cv::Mat::zeros(15, 15, CV_32FC1);
temp.at<float>(7, 7) = 1;
temp.at<float>(3, 5) = 6;
temp.at<float>(8, 10) = 4;
temp.at<float>(11, 13) = 7;
temp.at<float>(10, 3) = 8;
temp.at<float>(7, 13) = 3;
vector<SRegionalMaxPoint> buffer_(5);
imregionalmax(temp, buffer_);
cv::Mat debug;
cv::cvtColor(temp, debug, cv::COLOR_GRAY2BGR);
for (auto it = buffer_.begin(); it != buffer_.end(); ++it)
{
circle(debug, cv::Point(it->col, it->row), 1, cv::Scalar(0, 255, 0));
}
This solution does not take plateaus into account so it is not exactly the same as matlab's imregionalmax()
I think you want to use the
MinMaxLoc(arr, mask=NULL)-> (minVal, maxVal, minLoc, maxLoc)
Finds global minimum and maximum in array or subarray
function on you image