Je compare deux images à l'aide de findHomography(). J'ai ajouté des modules supplémentaires de opencv_contrib dans OpenCV 3.1.0 utiliser des algorithmes Surf et tamise et de compiler pour les dernières architectures Android. Je peux compiler avec succès les bibliothèques en utilisant ndk-build
.Erreur lors de la lecture des images à l'aide d'imread OpenCV
Problème: Quand je lance l'application sur LG Nexus 5, je suis capable de lire des images en utilisant imread
mais quand je lance la même application sur LG Nexus 5X, imread
ne lit pas l'image. J'ai testé sur Samsung S6 et OnePlus X et ont le même problème. Ci-dessous ma méthode native:
#include <jni.h>
#include <string.h>
#include <stdio.h>
#include <android/log.h>
#include "opencv2/core/core.hpp"
#include "opencv2/features2d/features2d.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/calib3d/calib3d.hpp"
#include "opencv2/xfeatures2d/nonfree.hpp"
#include "opencv2/opencv.hpp"
using namespace std;
using namespace cv;
#define LOG_TAG "nonfree_jni"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
jboolean detect_features(JNIEnv * env, jstring scenePath, jstring objectPath) {
const char *nativeScenePath = (env)->GetStringUTFChars(scenePath, NULL);
const char *nativeObjectPath = (env)->GetStringUTFChars(objectPath, NULL);
nativeScenePath = env->GetStringUTFChars(scenePath, 0);
nativeObjectPath = env->GetStringUTFChars(objectPath, 0);
(env)->ReleaseStringUTFChars(scenePath, nativeScenePath);
(env)->ReleaseStringUTFChars(objectPath, nativeObjectPath);
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Object path: ----- %s \n", nativeObjectPath);
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Scene path: ----- %s \n", nativeScenePath);
Mat img_object = imread(nativeObjectPath, CV_LOAD_IMAGE_GRAYSCALE);
Mat img_scene = imread(nativeScenePath, CV_LOAD_IMAGE_GRAYSCALE);
if(!img_object.data || !img_scene.data){
LOGI(" --(!) Error reading images ");
return false;
}
//-- Step 1: Detect the keypoints using SURF Detector
int minHessian = 400;
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Image comparison rows: ----- %d \n", img_object.rows);
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Image comparison colums: ----- %d \n", img_object.cols);
// cv::xfeatures2d::SurfFeatureDetector detector(minHessian);
Ptr<cv::xfeatures2d::SurfFeatureDetector> detector = cv::xfeatures2d::SurfFeatureDetector::create(minHessian);
std::vector<KeyPoint> keypoints_object, keypoints_scene;
detector->detect(img_object, keypoints_object);
detector->detect(img_scene, keypoints_scene);
//-- Step 2: Calculate descriptors (feature vectors)
// cv::xfeatures2d::SurfDescriptorExtractor extractor;
Ptr<cv::xfeatures2d::SurfDescriptorExtractor> extractor = cv::xfeatures2d::SurfDescriptorExtractor::create();
Mat descriptors_object, descriptors_scene;
extractor->compute(img_object, keypoints_object, descriptors_object);
extractor->compute(img_scene, keypoints_scene, descriptors_scene);
//-- Step 3: Matching descriptor vectors using FLANN matcher
FlannBasedMatcher matcher;
std::vector<DMatch> matches;
matcher.match(descriptors_object, descriptors_scene, matches);
double max_dist = 0; double min_dist = 100;
//-- Quick calculation of max and min distances between keypoints
for(int i = 0; i < descriptors_object.rows; i++)
{
double dist = matches[i].distance;
if (dist == 0) continue;
if(dist < min_dist) min_dist = dist;
if(dist > max_dist) max_dist = dist;
}
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "-- Max dist : %f \n", max_dist);
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "-- Min dist : %f \n", min_dist);
//-- Draw only "good" matches (i.e. whose distance is less than 3*min_dist)
std::vector<DMatch> good_matches;
for(int i = 0; i < descriptors_object.rows; i++)
{
if(matches[i].distance <= 0.1) //3*min_dist
{
good_matches.push_back(matches[i]);
}
}
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "FLANN total matches -----: %zu \n", matches.size());
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "FLANN good matches -----: %zu \n", good_matches.size());
Mat img_matches;
drawMatches(img_object, keypoints_object, img_scene, keypoints_scene,
good_matches, img_matches, Scalar::all(-1), Scalar::all(-1),
vector<char>(), DrawMatchesFlags::NOT_DRAW_SINGLE_POINTS);
//-- Localize the object
std::vector<Point2f> obj;
std::vector<Point2f> scene;
for(int i = 0; i < good_matches.size(); i++)
{
//-- Get the keypoints from the good matches
obj.push_back(keypoints_object[ good_matches[i].queryIdx ].pt);
scene.push_back(keypoints_scene[ good_matches[i].trainIdx ].pt);
}
if (good_matches.size() >= 5)
{
Mat H = findHomography(obj, scene, CV_RANSAC);
//-- Get the corners from the image_1 (the object to be "detected")
std::vector<Point2f> obj_corners(4);
obj_corners[0] = cvPoint(0,0); obj_corners[1] = cvPoint(img_object.cols, 0);
obj_corners[2] = cvPoint(img_object.cols, img_object.rows); obj_corners[3] = cvPoint(0, img_object.rows);
std::vector<Point2f> scene_corners(4);
Mat output, matrix;
warpPerspective(img_object, output, H, { img_scene.cols, img_scene.rows });
////////////////////////////////////////////////////////////////////////////////
detector->detect(output, keypoints_object);
//-- Step 2: Calculate descriptors (feature vectors)
//cv::xfeatures2d::SurfDescriptorExtractor extractor;
Ptr<cv::xfeatures2d::SurfDescriptorExtractor> extractor = cv::xfeatures2d::SurfDescriptorExtractor::create();
extractor->compute(output, keypoints_object, descriptors_object);
extractor->compute(img_scene, keypoints_scene, descriptors_scene);
std::vector<std::vector<cv::DMatch>> matches2;
BFMatcher matcher;
matcher.knnMatch(descriptors_object, descriptors_scene, matches2, 2);
vector<cv::DMatch> good_matches2;
for (int i = 0; i < matches2.size(); ++i)
{
const float ratio = 0.8; // As in Lowe's paper; can be tuned
if (matches2[i][0].distance < ratio * matches2[i][1].distance)
{
good_matches2.push_back(matches2[i][0]);
}
}
if (matches2.size() == 0 || good_matches2.size() == 0) {
LOGI("End run!\n");
return false;
}
double ratioOfSimilarity = static_cast<double>(good_matches2.size())/static_cast<double>(matches2.size());
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Bruteforce total matches -----: %zu \n", matches2.size());
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Bruteforce good matches -----: %zu \n", good_matches2.size());
__android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, "Bruteforce similarity ratio -----: %f \n", ratioOfSimilarity);
if(ratioOfSimilarity >= 0.3) {
LOGI("End run!\n");
return true;
}
LOGI("End run!\n");
return false;
}
LOGI("End run!\n");
return false;
}
et les sauts de méthode à cette ligne:
if(!img_object.data || !img_scene.data){
LOGI(" --(!) Error reading images ");
return false;
}
Les appareils testés qui ne lisent pas l'image ont Android 6.0? – uelordi
@uelordi Oui certains ont Android 6.0 et certains ont Android 7.0. Mais j'ai testé sur Nexus 5 avec android 6.0.1 et ça marche. – Shahzeb
ok, donc ce n'est pas le problème d'autorisation d'exécution. lisez-vous les images de/sdcard? dans le stockage interne apk? – uelordi