Function sift

src/backend/opencl/kernel/sift.hpp:376–729

template<typename T, typename convAccT>
void sift(unsigned* out_feat, unsigned* out_dlen, Param& x_out, Param& y_out,
          Param& score_out, Param& ori_out, Param& size_out, Param& desc_out,
          Param img, const unsigned n_layers, const float contrast_thr,
          const float edge_thr, const float init_sigma, const bool double_input,
          const float img_scale, const float feature_ratio,
          const bool compute_GLOH) {
    using cl::Buffer;
    using cl::EnqueueArgs;
    using cl::Local;
    using cl::NDRange;
    using std::vector;

    auto kernels = getSiftKernels<T>();

    unsigned min_dim = std::min(img.info.dims[0], img.info.dims[1]);
    if (double_input) min_dim *= 2;

    const unsigned n_octaves = floor(log(min_dim) / log(2)) - 2;

    Param init_img =
        createInitialImage<T, convAccT>(img, init_sigma, double_input);

    vector<Param> gauss_pyr =
        buildGaussPyr<T, convAccT>(init_img, n_octaves, n_layers, init_sigma);

    vector<Param> dog_pyr =
        buildDoGPyr<T>(gauss_pyr, n_octaves, n_layers, kernels[0]);

    vector<bufptr> d_x_pyr;
    vector<bufptr> d_y_pyr;
    vector<bufptr> d_response_pyr;
    vector<bufptr> d_size_pyr;
    vector<bufptr> d_ori_pyr;
    vector<bufptr> d_desc_pyr;
    vector<unsigned> feat_pyr(n_octaves, 0);

    d_x_pyr.reserve(n_octaves);
    d_y_pyr.reserve(n_octaves);
    d_response_pyr.reserve(n_octaves);
    d_size_pyr.reserve(n_octaves);
    d_ori_pyr.reserve(n_octaves);
    d_desc_pyr.reserve(n_octaves);
    unsigned total_feat = 0;

    const unsigned d  = DescrWidth;
    const unsigned n  = DescrHistBins;
    const unsigned rb = GLOHRadialBins;
    const unsigned ab = GLOHAngularBins;
    const unsigned hb = GLOHHistBins;
    const unsigned desc_len =
        (compute_GLOH) ? (1 + (rb - 1) * ab) * hb : d * d * n;

    auto d_count = memAlloc<unsigned>(1);

    for (unsigned o = 0; o < n_octaves; o++) {
        if (dog_pyr[o].info.dims[0] - 2 * ImgBorder < 1 ||
            dog_pyr[o].info.dims[1] - 2 * ImgBorder < 1)
            continue;