CODEWITHSUNDEEP
c++opencvvisual-c++flannopencv3.0
Steven10172
Steven10172

Reputation: 2013

OpenCV Flann - Assertion Fails

I've been trying to setup a basic 3D point flann knnsearch, but so far haven't been able to successfully get it to work. I've tried many different things of which all come back with errors. For a while I had issues with cv::flann::Index kdtree(cv::Mat(cvPointCloud).reshape(1), indexParams); complaining about the type not matching. But it seems that I no longer see that error, but this one has replaced it and I have no idea what to do.

OpenCV Error: Assertion failed (mtype == type0 || (CV_MAT_CN(mtype) == CV_MAT_CN (type0) && ((1 << type0) & fixedDepthMask) != 0)) in cv::_OutputArray::create, f ile E:\opencv\source\modules\core\src\matrix.cpp, line 2280

My Code:

#include <opencv2/core/core.hpp>
#include <opencv2/flann/flann.hpp>
#include <iostream>
#include <stdio.h>
#include <random>


#define POINTS_IN_CLOUD 15
#define NUM_NEAREST_NEIGHBORS 2
#define NUM_SEARCHES 64



int main() {
    std::vector<cv::Point3f> cvPointCloud;

    // Build the cvPointCloud
    for (int i = 0; i < POINTS_IN_CLOUD; i++) {
        int x = rand() % 100;
        int y = rand() % 100;
        int z = rand() % 100;
        cvPointCloud.push_back(cv::Point3f(x, y, z));
    }

    // Loop through and print out the points in the cloud
    for (std::vector<cv::Point3f>::iterator it = cvPointCloud.begin(); it != cvPointCloud.end(); ++it) {
        std::cout << *it << "\t";
    }




    // KdTree with 4 random trees
    cv::flann::KDTreeIndexParams indexParams(4);
    cv::flann::Index kdtree(cv::Mat(cvPointCloud).reshape(1), indexParams);


    // Point to find nearest neighbors
    cv::Point3f pt = cv::Point3f(5, 5, 5);

    // Generate the search query
    std::vector<float> query;
    query.push_back(pt.x);
    query.push_back(pt.y);
    query.push_back(pt.z);


    std::vector<int> indices(NUM_NEAREST_NEIGHBORS);
    std::vector<int> dists(NUM_NEAREST_NEIGHBORS);
    kdtree.knnSearch(query, indices, dists, NUM_NEAREST_NEIGHBORS, cv::flann::SearchParams(NUM_SEARCHES));

    std::cout << indices[0];
    std::cout << dists[0];

    return 0;
}

If someone could point me into the right direction I would greatly appreciate it!

Upvotes: 1

Views: 2421

Answers (1)

Ha Dang
Ha Dang

Reputation: 1238

According to Opencv documentation, your variable 'dists' needs to be a 

std::vector<float> dists(NUM_NEAREST_NEIGHBORS);

not a 

std::vector<int> dists(NUM_NEAREST_NEIGHBORS);

as declared in your code.

Upvotes: 2

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