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minor optimization of SURF_GPU (reduce memory transfers, use structure of arrays instead of array of structures)

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Vladislav Vinogradov
2011-05-23 07:59:20 +00:00
parent 145a76faf4
commit 0b19f915be
5 changed files with 171 additions and 194 deletions
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20
modules/gpu/doc/feature_detection_and_description.rst
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@@ -15,6 +15,17 @@ This class is used for extracting Speeded Up Robust Features (SURF) from an imag
class SURF_GPU : public CvSURFParams
{
public:
enum KeypointLayout
{
SF_X = 0,
SF_Y,
SF_LAPLACIAN,
SF_SIZE,
SF_DIR,
SF_HESSIAN,
SF_FEATURE_STRIDE
};
//! the default constructor
SURF_GPU();
//! the full constructor taking all the necessary parameters
@@ -67,22 +78,15 @@ This class is used for extracting Speeded Up Robust Features (SURF) from an imag
GpuMat det, trace;
GpuMat maxPosBuffer;
GpuMat featuresBuffer;
GpuMat keypointsBuffer;
};
The class ``SURF_GPU`` implements Speeded Up Robust Features descriptor. There is a fast multi-scale Hessian keypoint detector that can be used to find the keypoints (which is the default option). But the descriptors can also be computed for the user-specified keypoints. Only 8 bit grayscale images are supported.
The class ``SURF_GPU`` can store results in the GPU and CPU memory. It provides functions to convert results between CPU and GPU version ( ``uploadKeypoints``, ``downloadKeypoints``, ``downloadDescriptors`` ). The format of CPU results is the same as ``SURF`` results. GPU results are stored in ``GpuMat`` . The ``keypoints`` matrix is a one-row matrix of the ``CV_32FC6`` type. It contains 6 float values per feature: ``x, y, laplacian, size, dir, hessian`` . The ``descriptors`` matrix is
:math:`\texttt{nFeatures} \times \texttt{descriptorSize}` matrix with the ``CV_32FC1`` type.
The class ``SURF_GPU`` can store results in the GPU and CPU memory. It provides functions to convert results between CPU and GPU version ( ``uploadKeypoints``, ``downloadKeypoints``, ``downloadDescriptors`` ). The format of CPU results is the same as ``SURF`` results. GPU results are stored in ``GpuMat`` . The ``keypoints`` matrix is :math:`\texttt{nFeatures} \times 6` matrix with the ``CV_32FC1`` type. keypoints.ptr<float>(SF_X)[i] will contain x coordinate of i'th feature. keypoints.ptr<float>(SF_Y)[i] will contain y coordinate of i'th feature. keypoints.ptr<float>(SF_LAPLACIAN)[i] will contain laplacian sign of i'th feature. keypoints.ptr<float>(SF_SIZE)[i] will contain size of i'th feature. keypoints.ptr<float>(SF_DIR)[i] will contain orientation of i'th feature. keypoints.ptr<float>(SF_HESSIAN)[i] will contain response of i'th feature. The ``descriptors`` matrix is :math:`\texttt{nFeatures} \times \texttt{descriptorSize}` matrix with the ``CV_32FC1`` type.
The class ``SURF_GPU`` uses some buffers and provides access to it. All buffers can be safely released between function calls.
**Note:**
By default for user provided keypoints the class ``SURF_GPU`` recalculates keypoint's orientation and returns reodered/filtered keypoints array and coresponding decriptors array.
See Also: :c:type:`SURF`
.. index:: gpu::BruteForceMatcher_GPU