OpenCV - linker error when implementing a new descriptor - rotation invariant BRIEF

Question

As part of my research on binary descriptor, I'm implementing a rotation invariant version of BRIEF. Basically, I rotate the sampling points by the angle of the patch (given from the detector).

Now, I'm having linking problems with the function:

AlgorithmInfo* info() const;

I'm getting "unresolved external symbol" with the function's name.

Here is my code: in features2d.hpp":

class CV_EXPORTS InvariantBriefDescriptorExtractor : public DescriptorExtractor
{
public:
    static const int PATCH_SIZE = 48;
    static const int KERNEL_SIZE = 9;
    // bytes is a length of descriptor in bytes. It can be equal 16, 32 or 64 bytes.
    InvariantBriefDescriptorExtractor(int bytes = 32);

    virtual void read(const FileNode&);
    virtual void write(FileStorage&) const;

    virtual int descriptorSize() const;
    virtual int descriptorType() const;


    AlgorithmInfo* info() const;

protected:
    virtual void computeImpl(const Mat& image, vector<KeyPoint>& keypoints, Mat& descriptors) const;
    typedef void(*PixelTestFn)(const Mat&, const vector<KeyPoint>&,  const int *, Mat&);

    int bytes_;
    PixelTestFn test_fn_;
    static int bit_pattern_64_[512 * 4];
};

And the file BriefRI.cpp (which contains the implementation):

#include "precomp.hpp"
#include <algorithm>
#include <vector>

#include <iostream>
#include <iomanip>

using namespace cv;

static void calculateSums(const Mat &sum, const int &count, const int *pattern, float &cos_theta, float &sin_theta, KeyPoint pt);

inline int smoothedSum(const Mat& sum, const KeyPoint& pt, int y, int x)
{
    static const int HALF_KERNEL = BriefDescriptorExtractor::KERNEL_SIZE / 2;

    int img_y = (int)(pt.pt.y + 0.5) + y;
    int img_x = (int)(pt.pt.x + 0.5) + x;
    return   sum.at<int>(img_y + HALF_KERNEL + 1, img_x + HALF_KERNEL + 1)
        - sum.at<int>(img_y + HALF_KERNEL + 1, img_x - HALF_KERNEL)
        - sum.at<int>(img_y - HALF_KERNEL, img_x + HALF_KERNEL + 1)
        + sum.at<int>(img_y - HALF_KERNEL, img_x - HALF_KERNEL);
}

static void pixelTests16(const Mat& sum, const std::vector<KeyPoint>& keypoints, const int *pattern, Mat& descriptors)
{
    for (int i = 0; i < (int)keypoints.size(); ++i)
    {
        uchar* desc = descriptors.ptr(i);
        const KeyPoint& pt = keypoints[i];

        float angle = pt.angle;
        angle *= (float)(CV_PI / 180.f);
        float cos_theta = cos(angle);
        float sin_theta = sin(angle);
        int count = 0;

        for (int ix = 0; ix < 16; ix++){
            for (int jx = 7; jx >= 0; jx--){

                int suma, sumb;
                calculateSums(sum, count, pattern,cos_theta, sin_theta, pt);
                desc[ix] += (uchar)((suma< sumb) << jx);
                count += 4;
            }
        }
    }
}

static void pixelTests32(const Mat& sum, const std::vector<KeyPoint>& keypoints, const int *pattern, Mat& descriptors)
{
    for (int i = 0; i < (int)keypoints.size(); ++i)
    {
        uchar* desc = descriptors.ptr(i);
        const KeyPoint& pt = keypoints[i];

        float angle = pt.angle;
        angle *= (float)(CV_PI / 180.f);
        float cos_theta = cos(angle);
        float sin_theta = sin(angle);
        int count = 0;

        for (int ix = 0; ix < 32; ix++){
            for (int jx = 7; jx >= 0; jx--){

                int suma, sumb;
                calculateSums(sum, count, pattern,cos_theta, sin_theta, pt);
                desc[ix] += (uchar)((suma< sumb) << jx);
                count += 4;
            }
        }


    }
}

static void pixelTests64(const Mat& sum, const std::vector<KeyPoint>& keypoints, const int *pattern, Mat& descriptors)
{
    for (int i = 0; i < (int)keypoints.size(); ++i)
    {
        uchar* desc = descriptors.ptr(i);
        const KeyPoint& pt = keypoints[i];

        float angle = pt.angle;
        angle *= (float)(CV_PI / 180.f);
        float cos_theta = cos(angle);
        float sin_theta = sin(angle);
        int count = 0;

        for (int ix = 0; ix < 64; ix++){
            for (int jx = 7; jx >= 0; jx--){

                int suma, sumb;
                calculateSums(sum, count,pattern, cos_theta, sin_theta, pt);
                desc[ix] += (uchar)((suma< sumb) << jx);
                count += 4;
            }
        }

    }
}

static void calculateSums(const Mat &sum, const int &count, const int *pattern, float &cos_theta, float &sin_theta, KeyPoint pt){
    int ax = pattern[count];
    int ay = pattern[count + 1];

    int bx = pattern[count + 2];
    int by = pattern[count + 3];

    int ax2 = ((float)ax)*cos_theta - ((float)ay)*sin_theta;
    int ay2 = ((float)ax)*sin_theta + ((float)ay)*cos_theta;
    int bx2 = ((float)bx)*cos_theta - ((float)by)*sin_theta;
    int by2 = ((float)bx)*sin_theta + ((float)by)*cos_theta;

    int suma = smoothedSum(sum, pt, ay, ax);
    int sumb = smoothedSum(sum, pt, by, bx);
}

namespace cv
{

    InvariantBriefDescriptorExtractor::InvariantBriefDescriptorExtractor(int bytes) :
        bytes_(bytes), test_fn_(NULL)
    {
        switch (bytes)
        {
        case 16:
            test_fn_ = pixelTests16;
            break;
        case 32:
            test_fn_ = pixelTests32;
            break;
        case 64:
            test_fn_ = pixelTests64;
            break;
        default:
            CV_Error(CV_StsBadArg, "bytes must be 16, 32, or 64");
        }
    }

    int InvariantBriefDescriptorExtractor::descriptorSize() const
    {
        return bytes_;
    }

    int InvariantBriefDescriptorExtractor::descriptorType() const
    {
        return CV_8UC1;
    }

    void InvariantBriefDescriptorExtractor::read(const FileNode& fn)
    {
        int dSize = fn["descriptorSize"];
        switch (dSize)
        {
        case 16:
            test_fn_ = pixelTests16;
            break;
        case 32:
            test_fn_ = pixelTests32;
            break;
        case 64:
            test_fn_ = pixelTests64;
            break;
        default:
            CV_Error(CV_StsBadArg, "descriptorSize must be 16, 32, or 64");
        }
        bytes_ = dSize;
    }

    void InvariantBriefDescriptorExtractor::write(FileStorage& fs) const
    {
        fs << "descriptorSize" << bytes_;
    }

    void InvariantBriefDescriptorExtractor::computeImpl(const Mat& image, std::vector<KeyPoint>& keypoints, Mat& descriptors) const
    {
        // Construct integral image for fast smoothing (box filter)
        Mat sum;

        Mat grayImage = image;
        if (image.type() != CV_8U) cvtColor(image, grayImage, CV_BGR2GRAY);

        ///TODO allow the user to pass in a precomputed integral image
        //if(image.type() == CV_32S)
        //  sum = image;
        //else

        integral(grayImage, sum, CV_32S);

        //Remove keypoints very close to the border
        KeyPointsFilter::runByImageBorder(keypoints, image.size(), PATCH_SIZE / 2 + KERNEL_SIZE / 2);

        descriptors = Mat::zeros((int)keypoints.size(), bytes_, CV_8U);
        test_fn_(sum, keypoints, bit_pattern_64_,descriptors);
    }


    int InvariantBriefDescriptorExtractor::  bit_pattern_64_[512 * 4] =
    { -1, -2, -1, 7
    , -1, -14, 3, -3
    , -2, 1, 2, 11
    , 6, 1, -7, -10
    , 2, 13, 0, -1
    , 5, -14, -3, 5
    , 8, -2, 4, 2
    , 8, -11, 5, -15
(LONG LIST)

Thanks in advance!

Gil

berak · Accepted Answer · 2014-06-27T14:45:00.690

there is a CV_INIT_ALGORITHM macro available (within, but not outside) the opencv libs. it is used to implement the Algorithm::init() method. you set the class name for create, and expose member vars of your algo to get() and set() functions, and to write()/read() serialization.

here is an example for KAZE (taken from features2d_init.cpp):

 CV_INIT_ALGORITHM(KAZE, "Feature2D.KAZE",
              obj.info()->addParam(obj, "upright", obj.upright);
              obj.info()->addParam(obj, "extended", obj.extended))

so , to add to the features2d lib, you will have to add some similar code for your extractor there.

also, adding a line to bool cv::initModule_features2d(void) (at the end of features2d_init.cpp) might be nessecary

in the meantime, as a preliminary duct-tape-fix (also, while you're trying your code outside the features2d module), you could as well do a dummy impl:

class CV_EXPORTS InvariantBriefDescriptorExtractor : public DescriptorExtractor
{
public:

    // ...

    AlgorithmInfo* info() const { return 0; }

(btw, imho your computeImpl function does not match the inherited one from DescriptorExtractor, might be the next problem.)

you're the greatest! it compiles after adding some code to features2d_init.cpp . Do you think I can add it to OpenCV? — GilLevi, Jun 27 '14 at 15:01
just dare to try ! (also, don't abandon the binboost project). they likely might ask to add some tests, iirc — berak, Jun 27 '14 at 15:03
Thanks for the comment. I just asked about BinBoost in opencv dev page (opened a new issue as a "feature") — GilLevi, Jun 27 '14 at 16:28

OpenCV - linker error when implementing a new descriptor - rotation invariant BRIEF

1 Answers1