1 // Ceres Solver - A fast non-linear least squares minimizer 2 // Copyright 2015 Google Inc. All rights reserved. 3 // http://ceres-solver.org/ 4 // 5 // Redistribution and use in source and binary forms, with or without 6 // modification, are permitted provided that the following conditions are met: 7 // 8 // * Redistributions of source code must retain the above copyright notice, 9 // this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above copyright notice, 11 // this list of conditions and the following disclaimer in the documentation 12 // and/or other materials provided with the distribution. 13 // * Neither the name of Google Inc. nor the names of its contributors may be 14 // used to endorse or promote products derived from this software without 15 // specific prior written permission. 16 // 17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 18 // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 21 // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22 // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25 // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27 // POSSIBILITY OF SUCH DAMAGE. 28 // 29 // Author: sameeragarwal@google.com (Sameer Agarwal) 30 // keir@google.com (Keir Mierle) 31 // 32 // Purpose : Class and struct definitions for parameter and residual blocks. 33 34 #ifndef CERES_INTERNAL_RESIDUAL_BLOCK_H_ 35 #define CERES_INTERNAL_RESIDUAL_BLOCK_H_ 36 37 #include <cstdint> 38 #include <memory> 39 #include <string> 40 #include <vector> 41 42 #include "ceres/cost_function.h" 43 #include "ceres/internal/port.h" 44 #include "ceres/stringprintf.h" 45 #include "ceres/types.h" 46 47 namespace ceres { 48 49 class LossFunction; 50 51 namespace internal { 52 53 class ParameterBlock; 54 55 // A term in the least squares problem. The mathematical form of each term in 56 // the overall least-squares cost function is: 57 // 58 // 1 59 // --- loss_function( || cost_function(block1, block2, ...) ||^2 ), 60 // 2 61 // 62 // Storing the cost function and the loss function separately permits optimizing 63 // the problem with standard non-linear least techniques, without requiring a 64 // more general non-linear solver. 65 // 66 // The residual block stores pointers to but does not own the cost functions, 67 // loss functions, and parameter blocks. 68 class CERES_EXPORT_INTERNAL ResidualBlock { 69 public: 70 // Construct the residual block with the given cost/loss functions. Loss may 71 // be null. The index is the index of the residual block in the Program's 72 // residual_blocks array. 73 ResidualBlock(const CostFunction* cost_function, 74 const LossFunction* loss_function, 75 const std::vector<ParameterBlock*>& parameter_blocks, 76 int index); 77 78 // Evaluates the residual term, storing the scalar cost in *cost, the residual 79 // components in *residuals, and the jacobians between the parameters and 80 // residuals in jacobians[i], in row-major order. If residuals is NULL, the 81 // residuals are not computed. If jacobians is NULL, no jacobians are 82 // computed. If jacobians[i] is NULL, then the jacobian for that parameter is 83 // not computed. 84 // 85 // cost must not be null. 86 // 87 // Evaluate needs scratch space which must be supplied by the caller via 88 // scratch. The array should have at least NumScratchDoublesForEvaluate() 89 // space available. 90 // 91 // The return value indicates the success or failure. If the function returns 92 // false, the caller should expect the output memory locations to have 93 // been modified. 94 // 95 // The returned cost and jacobians have had robustification and local 96 // parameterizations applied already; for example, the jacobian for a 97 // 4-dimensional quaternion parameter using the "QuaternionParameterization" 98 // is num_residuals by 3 instead of num_residuals by 4. 99 // 100 // apply_loss_function as the name implies allows the user to switch 101 // the application of the loss function on and off. 102 bool Evaluate(bool apply_loss_function, 103 double* cost, 104 double* residuals, 105 double** jacobians, 106 double* scratch) const; 107 cost_function()108 const CostFunction* cost_function() const { return cost_function_; } loss_function()109 const LossFunction* loss_function() const { return loss_function_; } 110 111 // Access the parameter blocks for this residual. The array has size 112 // NumParameterBlocks(). parameter_blocks()113 ParameterBlock* const* parameter_blocks() const { 114 return parameter_blocks_.get(); 115 } 116 117 // Number of variable blocks that this residual term depends on. NumParameterBlocks()118 int NumParameterBlocks() const { 119 return cost_function_->parameter_block_sizes().size(); 120 } 121 122 // The size of the residual vector returned by this residual function. NumResiduals()123 int NumResiduals() const { return cost_function_->num_residuals(); } 124 125 // The minimum amount of scratch space needed to pass to Evaluate(). 126 int NumScratchDoublesForEvaluate() const; 127 128 // This residual block's index in an array. index()129 int index() const { return index_; } set_index(int index)130 void set_index(int index) { index_ = index; } 131 ToString()132 std::string ToString() const { 133 return StringPrintf("{residual block; index=%d}", index_); 134 } 135 136 private: 137 const CostFunction* cost_function_; 138 const LossFunction* loss_function_; 139 std::unique_ptr<ParameterBlock*[]> parameter_blocks_; 140 141 // The index of the residual, typically in a Program. This is only to permit 142 // switching from a ResidualBlock* to an index in the Program's array, needed 143 // to do efficient removals. 144 int32_t index_; 145 }; 146 147 } // namespace internal 148 } // namespace ceres 149 150 #endif // CERES_INTERNAL_RESIDUAL_BLOCK_H_ 151