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<html><head><title>dlib C++ Library - surf_abstract.h</title></head><body bgcolor='white'><pre> |
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<font color='#009900'>// Copyright (C) 2009 Davis E. King ([email protected]) |
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</font><font color='#009900'>// License: Boost Software License See LICENSE.txt for the full license. |
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</font><font color='#0000FF'>#undef</font> DLIB_SURf_ABSTRACT_H_ |
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<font color='#0000FF'>#ifdef</font> DLIB_SURf_ABSTRACT_H_ |
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<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='hessian_pyramid_abstract.h.html'>hessian_pyramid_abstract.h</a>" |
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<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='../geometry/vector_abstract.h.html'>../geometry/vector_abstract.h</a>" |
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<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='../matrix/matrix_abstract.h.html'>../matrix/matrix_abstract.h</a>" |
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<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='../image_processing/generic_image.h.html'>../image_processing/generic_image.h</a>" |
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<font color='#0000FF'>namespace</font> dlib |
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<b>{</b> |
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<font color='#009900'>/* |
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The functions in this file implement the components of the SURF algorithm |
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for extracting scale invariant feature descriptors from images. |
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For the full story on what this algorithm does and how it works |
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you should refer to the following papers. |
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This is the original paper which introduced the algorithm: |
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SURF: Speeded Up Robust Features |
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By Herbert Bay, Tinne Tuytelaars, and Luc Van Gool |
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This paper provides a nice detailed overview of how the algorithm works: |
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Notes on the OpenSURF Library by Christopher Evans |
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*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'><u>double</u></font> <b><a name='gaussian'></a>gaussian</b> <font face='Lucida Console'>(</font> |
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<font color='#0000FF'><u>double</u></font> x, |
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<font color='#0000FF'><u>double</u></font> y, |
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<font color='#0000FF'><u>double</u></font> sig |
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<font face='Lucida Console'>)</font>; |
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<font color='#009900'>/*! |
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requires |
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- sig > 0 |
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ensures |
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- computes and returns the value of a 2D Gaussian function with mean 0 |
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and standard deviation sig at the given (x,y) point. |
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!*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'>typename</font> integral_image_type, <font color='#0000FF'>typename</font> T<font color='#5555FF'>></font> |
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<font color='#0000FF'><u>double</u></font> <b><a name='compute_dominant_angle'></a>compute_dominant_angle</b> <font face='Lucida Console'>(</font> |
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<font color='#0000FF'>const</font> integral_image_type<font color='#5555FF'>&</font> img, |
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<font color='#0000FF'>const</font> dlib::vector<font color='#5555FF'><</font>T,<font color='#979000'>2</font><font color='#5555FF'>></font><font color='#5555FF'>&</font> center, |
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<font color='#0000FF'>const</font> <font color='#0000FF'><u>double</u></font><font color='#5555FF'>&</font> scale |
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<font face='Lucida Console'>)</font>; |
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<font color='#009900'>/*! |
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requires |
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- integral_image_type == an object such as dlib::integral_image or another |
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type that implements the interface defined in image_transforms/integral_image_abstract.h |
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- scale > 0 |
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- get_rect(img).contains(centered_rect(center, 17*scale, 17*scale)) == true |
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(i.e. center can't be within 17*scale pixels of the edge of the image) |
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ensures |
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- computes and returns the dominant angle (i.e. the angle of the dominant gradient) |
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at the given center point and scale in img. |
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- The returned angle is in radians. Specifically, if the angle is described by |
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a vector vect then the angle is exactly the value of std::atan2(vect.y(), vect.x()) |
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!*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'>typename</font> integral_image_type, <font color='#0000FF'>typename</font> T, <font color='#0000FF'>typename</font> MM, <font color='#0000FF'>typename</font> L<font color='#5555FF'>></font> |
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<font color='#0000FF'><u>void</u></font> <b><a name='compute_surf_descriptor'></a>compute_surf_descriptor</b> <font face='Lucida Console'>(</font> |
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<font color='#0000FF'>const</font> integral_image_type<font color='#5555FF'>&</font> img, |
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<font color='#0000FF'>const</font> dlib::vector<font color='#5555FF'><</font>T,<font color='#979000'>2</font><font color='#5555FF'>></font><font color='#5555FF'>&</font> center, |
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<font color='#0000FF'>const</font> <font color='#0000FF'><u>double</u></font> scale, |
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<font color='#0000FF'>const</font> <font color='#0000FF'><u>double</u></font> angle, |
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matrix<font color='#5555FF'><</font><font color='#0000FF'><u>double</u></font>,<font color='#979000'>64</font>,<font color='#979000'>1</font>,MM,L<font color='#5555FF'>></font><font color='#5555FF'>&</font> des |
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<font face='Lucida Console'>)</font> |
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<font color='#009900'>/*! |
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requires |
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- integral_image_type == an object such as dlib::integral_image or another |
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type that implements the interface defined in image_transforms/integral_image_abstract.h |
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- scale > 0 |
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- get_rect(img).contains(centered_rect(center, 32*scale, 32*scale)) == true |
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(i.e. center can't be within 32*scale pixels of the edge of the image) |
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ensures |
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- computes the 64 dimensional SURF descriptor vector of a box centered |
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at the given center point, tilted at an angle determined by the given |
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angle, and sized according to the given scale. |
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- #des == the computed SURF descriptor vector extracted from the img object. |
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- The angle is measured in radians and measures the degree of counter-clockwise |
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rotation around the center point. This is the same kind of rotation as is |
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performed by the dlib::rotate_point() function. |
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!*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'>struct</font> <b><a name='surf_point'></a>surf_point</b> |
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<b>{</b> |
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<font color='#009900'>/*! |
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WHAT THIS OBJECT REPRESENTS |
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This object represents a detected SURF point. The meanings of |
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its fields are defined below in the get_surf_points() function. |
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!*/</font> |
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interest_point p; |
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matrix<font color='#5555FF'><</font><font color='#0000FF'><u>double</u></font>,<font color='#979000'>64</font>,<font color='#979000'>1</font><font color='#5555FF'>></font> des; |
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<font color='#0000FF'><u>double</u></font> angle; |
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<b>}</b>; |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'><u>void</u></font> <b><a name='serialize'></a>serialize</b> <font face='Lucida Console'>(</font> |
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<font color='#0000FF'>const</font> surf_point<font color='#5555FF'>&</font> item, |
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std::ostream<font color='#5555FF'>&</font> out |
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<font face='Lucida Console'>)</font>; |
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<font color='#009900'>/*! |
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provides serialization support |
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!*/</font> |
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<font color='#0000FF'><u>void</u></font> <b><a name='deserialize'></a>deserialize</b> <font face='Lucida Console'>(</font> |
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surf_point<font color='#5555FF'>&</font> item, |
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std::istream<font color='#5555FF'>&</font> in |
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<font face='Lucida Console'>)</font>; |
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<font color='#009900'>/*! |
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provides serialization support |
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!*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<font color='#0000FF'>template</font> <font color='#5555FF'><</font><font color='#0000FF'>typename</font> image_type<font color='#5555FF'>></font> |
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<font color='#0000FF'>const</font> std::vector<font color='#5555FF'><</font>surf_point<font color='#5555FF'>></font> <b><a name='get_surf_points'></a>get_surf_points</b> <font face='Lucida Console'>(</font> |
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<font color='#0000FF'>const</font> image_type<font color='#5555FF'>&</font> img, |
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<font color='#0000FF'><u>long</u></font> max_points <font color='#5555FF'>=</font> <font color='#979000'>10000</font>, |
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<font color='#0000FF'><u>double</u></font> detection_threshold <font color='#5555FF'>=</font> <font color='#979000'>30.0</font> |
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<font face='Lucida Console'>)</font>; |
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<font color='#009900'>/*! |
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requires |
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- max_points > 0 |
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- detection_threshold >= 0 |
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- image_type == an image object that implements the interface defined in |
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dlib/image_processing/generic_image.h |
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- Let P denote the type of pixel in img, then we require: |
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- pixel_traits<P>::has_alpha == false |
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ensures |
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- This function runs the complete SURF algorithm on the given input image and |
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returns the points it found. |
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- returns a vector V such that: |
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- V.size() <= max_points |
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- for all valid i: |
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- V[i] == a SURF point found in the given input image img |
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- V[i].p == the interest_point extracted from the hessian pyramid for this |
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SURF point. |
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- V[i].des == the SURF descriptor for this point (calculated using |
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compute_surf_descriptor()) |
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- V[i].angle == the angle of the SURF box at this point (calculated using |
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compute_dominant_angle()) |
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- V[i].p.score >= detection_threshold |
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!*/</font> |
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<font color='#009900'>// ---------------------------------------------------------------------------------------- |
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</font> |
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<b>}</b> |
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<font color='#0000FF'>#endif</font> <font color='#009900'>// DLIB_SURf_ABSTRACT_H_ |
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</font> |
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</pre></body></html> |
