1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 /* $Id: db_image_homography.h,v 1.2 2011/06/17 14:03:31 mbansal Exp $ */ 18 19 #ifndef DB_IMAGE_HOMOGRAPHY 20 #define DB_IMAGE_HOMOGRAPHY 21 22 23 24 /***************************************************************** 25 * Lean and mean begins here * 26 *****************************************************************/ 27 28 #include "db_framestitching.h" 29 /*! 30 * \defgroup LMImageHomography (LM) Image Homography Estimation (feature based) 31 */ 32 /*\{*/ 33 /*! 34 Solve for projective H such that xp~Hx. Prior normalization is not necessary, 35 although desirable for numerical conditioning 36 \param H image projective (out) 37 \param x1 image 1 point 1 38 \param x2 image 1 point 2 39 \param x3 image 1 point 3 40 \param x4 image 1 point 4 41 \param xp1 image 2 point 1 42 \param xp2 image 2 point 2 43 \param xp3 image 2 point 3 44 \param xp4 image 2 point 4 45 */ 46 DB_API void db_StitchProjective2D_4Points(double H[9], 47 double x1[3],double x2[3],double x3[3],double x4[3], 48 double xp1[3],double xp2[3],double xp3[3],double xp4[3]); 49 50 /*! 51 Solve for affine H such that xp~Hx. Prior normalization is not necessary, 52 although desirable for numerical conditioning 53 \param H image projective (out) 54 \param x1 image 1 point 1 55 \param x2 image 1 point 2 56 \param x3 image 1 point 3 57 \param xp1 image 2 point 1 58 \param xp2 image 2 point 2 59 \param xp3 image 2 point 3 60 */ 61 DB_API void db_StitchAffine2D_3Points(double H[9], 62 double x1[3],double x2[3],double x3[3], 63 double xp1[3],double xp2[3],double xp3[3]); 64 65 /*! 66 Solve for rotation R such that xp~Rx. 67 Image points have to be of unit norm for the least squares to be meaningful. 68 \param R image rotation (out) 69 \param x1 image 1 point 1 70 \param x2 image 1 point 2 71 \param xp1 image 2 point 1 72 \param xp2 image 2 point 2 73 */ 74 inline void db_StitchCameraRotation_2Points(double R[9], 75 /*Image points have to be of unit norm 76 for the least squares to be meaningful*/ 77 double x1[3],double x2[3], 78 double xp1[3],double xp2[3]) 79 { 80 double* x[2]; 81 double* xp[2]; 82 double scale,t[3]; 83 84 x[0]=x1; 85 x[1]=x2; 86 xp[0]=xp1; 87 xp[1]=xp2; 88 db_StitchSimilarity3DRaw(&scale,R,t,xp,x,2,1,0,1,0); 89 } 90 91 /*! 92 Solve for a homography H generated by a rotation R with a common unknown focal length f, i.e. 93 H=diag(f,f,1)*R*diag(1/f,1/f,1) such that xp~Hx. 94 If signed_disambiguation is true, the points are 95 required to be in front of the camera. No specific normalization of the homogenous points 96 is required, although it could be desirable to keep x1,x2,xp1 and xp2 of reasonable magnitude. 97 If a solution is obtained the function returns 1, otherwise 0. If the focal length is desired 98 a valid pointer should be passed in f 99 */ 100 DB_API int db_StitchRotationCommonFocalLength_3Points(double H[9],double x1[3],double x2[3],double x3[3], 101 double xp1[3],double xp2[3],double xp3[3],double *f=0,int signed_disambiguation=1); 102 103 /*! 104 Find scale, rotation and translation of the similarity that 105 takes the nr_points inhomogenous 2D points X to Xp, 106 i.e. for the homogenous equivalents 107 Xp and X we would have 108 \code 109 Xp~ 110 [sR t]*X 111 [0 1] 112 \endcode 113 If orientation_preserving is true, R is restricted such that det(R)>0. 114 allow_scaling, allow_rotation and allow_translation allow s,R and t 115 to differ from 1,Identity and 0 116 117 Full similarity takes the following on 550MHz: 118 \code 119 0.9 microseconds with 2 points 120 1.0 microseconds with 3 points 121 1.1 microseconds with 4 points 122 1.3 microseconds with 5 points 123 1.4 microseconds with 6 points 124 1.7 microseconds with 10 points 125 9 microseconds with 100 points 126 130 microseconds with 1000 points 127 1.3 milliseconds with 10000 points 128 35 milliseconds with 100000 points 129 350 milliseconds with 1000000 points 130 \endcode 131 132 Without orientation_preserving: 133 \code 134 3 points is minimal for (s,R,t) (R,t) 135 2 points is minimal for (s,t) (s,R) (R) 136 1 point is minimal for (s) (t) 137 \endcode 138 139 With orientation_preserving: 140 \code 141 2 points is minimal for (s,R,t) (R,t) (s,t) 142 1 point is minimal for (s,R) (R) (s) (t) 143 \endcode 144 \param scale (out) 145 \param R 2D rotation (out) 146 \param t 2D translation (out) 147 \param Xp (nr_points x 2) pointer to array of image points 148 \param X (nr_points x 2 ) pointer to array of image points 149 \param nr_points number of points 150 \param orientation_preserving 151 \param allow_scaling compute scale (if 0, scale=1) 152 \param allow_rotation compute rotation (if 0, R=[I]) 153 \param allow_translation compute translation (if 0 t = [0,0]') 154 */ 155 DB_API void db_StitchSimilarity2DRaw(double *scale,double R[4],double t[2], 156 double **Xp,double **X,int nr_points,int orientation_preserving=1, 157 int allow_scaling=1,int allow_rotation=1,int allow_translation=1); 158 /*! 159 See db_StitchRotationCommonFocalLength_3Points(). 160 \param H Image similarity transformation (out) 161 \param Xp (nr_points x 2) pointer to array of image points 162 \param X (nr_points x 2) pointer to array of image points 163 \param nr_points number of points 164 \param orientation_preserving 165 \param allow_scaling compute scale (if 0, scale=1) 166 \param allow_rotation compute rotation (if 0, R=[I]) 167 \param allow_translation compute translation (if 0 t = [0,0]') 168 */ 169 inline void db_StitchSimilarity2D(double H[9],double **Xp,double **X,int nr_points,int orientation_preserving=1, 170 int allow_scaling=1,int allow_rotation=1,int allow_translation=1) 171 { 172 double s,R[4],t[2]; 173 174 db_StitchSimilarity2DRaw(&s,R,t,Xp,X,nr_points,orientation_preserving, 175 allow_scaling,allow_rotation,allow_translation); 176 177 H[0]=s*R[0]; H[1]=s*R[1]; H[2]=t[0]; 178 H[3]=s*R[2]; H[4]=s*R[3]; H[5]=t[1]; 179 db_Zero2(H+6); 180 H[8]=1.0; 181 } 182 /*\}*/ 183 #endif /* DB_IMAGE_HOMOGRAPHY */ 184
