move the IncrementalFixedLagExample example to gtsam_unstable folder to fix the link error
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				|  | @ -1,272 +0,0 @@ | |||
| /* ----------------------------------------------------------------------------
 | ||||
| 
 | ||||
|  * GTSAM Copyright 2010-2025, Georgia Tech Research Corporation, | ||||
|  * Atlanta, Georgia 30332-0415 | ||||
|  * All Rights Reserved | ||||
|  * Authors: Frank Dellaert, et al. (see THANKS for the full author list) | ||||
| 
 | ||||
|  * See LICENSE for the license information | ||||
| 
 | ||||
|  * -------------------------------------------------------------------------- */ | ||||
| 
 | ||||
| /**
 | ||||
| *  @file   IncrementalFixedLagExample.cpp | ||||
| *  @brief  Example of incremental fixed-lag smoother using real-world data. | ||||
| *  @author Xiangcheng Hu (xhubd@connect.ust.hk), Frank Dellaert, Kevin Doherty | ||||
| *  @date   Janaury 15, 2025 | ||||
| * | ||||
| * Key objectives: | ||||
| *   - Validate `IncrementalFixedLagSmoother` functionality with real-world data. | ||||
| *   - Showcase how setting `findUnusedFactorSlots = true` addresses the issue #1452 in GTSAM, ensuring | ||||
| *     that unused factor slots (nullptrs) are correctly released when old factors are marginalized. | ||||
| * | ||||
| *  This example leverages pose measurements from a real scenario. The test data (named "IncrementalFixedLagSmootherTestData.txt") is | ||||
| *  based on the corridor_day sequence from the FusionPortable dataset (https://fusionportable.github.io/dataset/fusionportable/).
 | ||||
| *   - 1 prior factor derived from point cloud ICP alignment with a prior map. | ||||
| *   - 199 relative pose factors derived from FAST-LIO2 odometry. | ||||
| * | ||||
| *  Data Format (IncrementalFixedLagSmootherTestData.txt): | ||||
| *    1) PRIOR factor line: | ||||
| *       @code | ||||
| *       0 timestamp key x y z roll pitch yaw cov_6x6 | ||||
| *       @endcode | ||||
| *       - "0" indicates PRIOR factor. | ||||
| *       - "timestamp" is the observation time (in seconds). | ||||
| *       - "key" is the integer ID for the Pose3 variable. | ||||
| *       - (x, y, z, roll, pitch, yaw) define the pose. | ||||
| *       - "cov_6x6" is the full 6x6 covariance matrix (row-major). | ||||
| * | ||||
| *    2) BETWEEN factor line: | ||||
| *       @code | ||||
| *       1 timestamp key1 key2 x y z roll pitch yaw cov_6x6 | ||||
| *       @endcode | ||||
| *       - "1" indicates BETWEEN factor. | ||||
| *       - "timestamp" is the observation time (in seconds). | ||||
| *       - "key1" and "key2" are the integer IDs for the connected Pose3 variables. | ||||
| *       - (x, y, z, roll, pitch, yaw) define the relative pose between these variables. | ||||
| *       - "cov_6x6" is the full 6x6 covariance matrix (row-major). | ||||
| * | ||||
| *  See also: | ||||
| *   - GTSAM Issue #1452: https://github.com/borglab/gtsam/issues/1452
 | ||||
| */ | ||||
| 
 | ||||
| // STL
 | ||||
| #include <iostream> | ||||
| #include <string> | ||||
| // GTSAM
 | ||||
| #include <gtsam/geometry/Pose3.h> | ||||
| #include <gtsam/nonlinear/ISAM2.h> | ||||
| #include <gtsam/nonlinear/Values.h> | ||||
| #include <gtsam/nonlinear/NonlinearFactorGraph.h> | ||||
| #include <gtsam/slam/BetweenFactor.h> | ||||
| #include <gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h> | ||||
| #include <gtsam/inference/Symbol.h> | ||||
| #include <gtsam/slam/dataset.h>  // for writeG2o | ||||
| 
 | ||||
| using namespace std; | ||||
| using namespace gtsam; | ||||
| // Shorthand for symbols
 | ||||
| using symbol_shorthand::X;  // Pose3 (x,y,z, roll, pitch, yaw)
 | ||||
| 
 | ||||
| // Factor types
 | ||||
| enum FactorType { | ||||
|     PRIOR = 0, | ||||
|     BETWEEN = 1 | ||||
| }; | ||||
| 
 | ||||
| typedef Eigen::Matrix<double, 6, 6> Matrix6; | ||||
| 
 | ||||
| /* ************************************************************************* */ | ||||
| /**
 | ||||
|  * @brief Read a 6x6 covariance matrix from an input string stream. | ||||
|  * | ||||
|  * @param iss Input string stream containing covariance entries. | ||||
|  * @return 6x6 covariance matrix. | ||||
|  */ | ||||
| Matrix6 readCovarianceMatrix(istringstream &iss) { | ||||
|     Matrix6 cov; | ||||
|     for (int r = 0; r < 6; ++r) { | ||||
|         for (int c = 0; c < 6; ++c) { | ||||
|             iss >> cov(r, c); | ||||
|         } | ||||
|     } | ||||
|     return cov; | ||||
| } | ||||
| 
 | ||||
| /* ************************************************************************* */ | ||||
| /**
 | ||||
|  * @brief Create a Pose3 object from individual pose parameters. | ||||
|  * | ||||
|  * @param x     Translation in x | ||||
|  * @param y     Translation in y | ||||
|  * @param z     Translation in z | ||||
|  * @param roll  Rotation about x-axis | ||||
|  * @param pitch Rotation about y-axis | ||||
|  * @param yaw   Rotation about z-axis | ||||
|  * @return Constructed Pose3 object | ||||
|  */ | ||||
| Pose3 createPose(double x, double y, double z, double roll, double pitch, double yaw) { | ||||
|     return Pose3(Rot3::RzRyRx(roll, pitch, yaw), Point3(x, y, z)); | ||||
| } | ||||
| 
 | ||||
| /* ************************************************************************* */ | ||||
| /**
 | ||||
|  * @brief Save the factor graph and estimates to a .g2o file (for visualization/debugging). | ||||
|  * | ||||
|  * @param graph       The factor graph | ||||
|  * @param estimate    Current estimates of all variables | ||||
|  * @param filename    Base filename for saving | ||||
|  * @param iterCount   Iteration count to differentiate successive outputs | ||||
|  */ | ||||
| void saveG2oGraph(const NonlinearFactorGraph &graph, const Values &estimate, | ||||
|                   const string &filename, int iterCount) { | ||||
|     // Create zero-padded iteration count
 | ||||
|     string countStr = to_string(iterCount); | ||||
|     string paddedCount = string(5 - countStr.length(), '0') + countStr; | ||||
|     string fullFilename = filename + "_" + paddedCount + ".g2o"; | ||||
|     // Write graph and estimates to g2o file
 | ||||
|     writeG2o(graph, estimate, fullFilename); | ||||
|     cout << "\nSaved graph to: " << fullFilename << endl; | ||||
| } | ||||
| 
 | ||||
| /* ************************************************************************* */ | ||||
| /**
 | ||||
|  * @brief Main function: Reads poses data from a text file and performs incremental fixed-lag smoothing. | ||||
|  * | ||||
|  * Data Flow: | ||||
|  *  1) Parse lines from "IncrementalFixedLagSmootherTestData.txt". | ||||
|  *  2) For each line: | ||||
|  *      - If it's a PRIOR factor, add a PriorFactor with a specified pose and covariance. | ||||
|  *      - If it's a BETWEEN factor, add a BetweenFactor with a relative pose and covariance. | ||||
|  *      - Insert new variables with initial guesses into the current solution if they don't exist. | ||||
|  *  3) Update the fixed-lag smoother (with iSAM2 inside) to incrementally optimize and marginalize out old poses | ||||
|  *     beyond the specified lag window. | ||||
|  *  4) Repeat until all lines are processed. | ||||
|  *  5) Save the resulting factor graph and estimate of the last sliding window to a .g2o file. | ||||
|  */ | ||||
| int main() { | ||||
|     string factor_loc = findExampleDataFile("issue1452.txt"); | ||||
|     ifstream factor_file(factor_loc.c_str()); | ||||
|     cout << "Reading factors data file: " << factor_loc << endl; | ||||
| 
 | ||||
|     // Configure ISAM2 parameters for the fixed-lag smoother
 | ||||
|     ISAM2Params isamParameters; | ||||
|     isamParameters.relinearizeThreshold = 0.1; | ||||
|     isamParameters.relinearizeSkip = 1; | ||||
| 
 | ||||
|     // Important!!!!!! Key parameter to ensure old factors are released after marginalization
 | ||||
|     isamParameters.findUnusedFactorSlots = true; | ||||
|     // Initialize fixed-lag smoother with a 1-second lag window
 | ||||
|     const double lag = 1.0; | ||||
|     IncrementalFixedLagSmoother smoother(lag, isamParameters); | ||||
|     // Print the iSAM2 parameters (optional)
 | ||||
|     isamParameters.print(); | ||||
| 
 | ||||
|     // Containers for incremental updates
 | ||||
|     NonlinearFactorGraph newFactors; | ||||
|     Values newValues; | ||||
|     FixedLagSmoother::KeyTimestampMap newTimestamps; | ||||
|     // For tracking the latest estimate of all states in the sliding window
 | ||||
|     Values currentEstimate; | ||||
|     Pose3 lastPose; | ||||
| 
 | ||||
|     // Read and process each line in the factor graph file
 | ||||
|     string line; | ||||
|     int lineCount = 0; | ||||
|     while (getline(factor_file, line)) { | ||||
|         if (line.empty()) continue;  // Skip empty lines
 | ||||
|         cout << "\n======================== Processing line " << ++lineCount | ||||
|              << " =========================" << endl; | ||||
| 
 | ||||
|         istringstream iss(line); | ||||
|         int factorType; | ||||
|         iss >> factorType; | ||||
|         // Check if the factor is PRIOR or BETWEEN
 | ||||
|         if (factorType == PRIOR) { | ||||
|             /**
 | ||||
|              * Format: PRIOR factor | ||||
|              * factor_type timestamp key pose(x y z roll pitch yaw) cov(6x6) | ||||
|              */ | ||||
|             double timestamp; | ||||
|             int key; | ||||
|             double x, y, z, roll, pitch, yaw; | ||||
|             iss >> timestamp >> key >> x >> y >> z >> roll >> pitch >> yaw; | ||||
|             Pose3 pose = createPose(x, y, z, roll, pitch, yaw); | ||||
|             Matrix6 cov = readCovarianceMatrix(iss); | ||||
|             auto noise = noiseModel::Gaussian::Covariance(cov); | ||||
|             // Add prior factor
 | ||||
|             newFactors.addPrior(X(key), pose, noise); | ||||
|             cout << "Add PRIOR factor on key " << key << endl; | ||||
|             // Provide initial guess if not already in the graph
 | ||||
|             if (!newValues.exists(X(key))) { | ||||
|                 newValues.insert(X(key), pose); | ||||
|                 newTimestamps[X(key)] = timestamp; | ||||
|             } | ||||
|         } else if (factorType == BETWEEN) { | ||||
|             /**
 | ||||
|              * Format: BETWEEN factor | ||||
|              * factor_type timestamp key1 key2 pose(x y z roll pitch yaw) cov(6x6) | ||||
|              */ | ||||
|             double timestamp; | ||||
|             int key1, key2; | ||||
|             iss >> timestamp >> key1 >> key2; | ||||
|             double x1, y1, z1, roll1, pitch1, yaw1; | ||||
|             iss >> x1 >> y1 >> z1 >> roll1 >> pitch1 >> yaw1; | ||||
|             Pose3 relativePose = createPose(x1, y1, z1, roll1, pitch1, yaw1); | ||||
|             Matrix6 cov = readCovarianceMatrix(iss); | ||||
|             auto noise = noiseModel::Gaussian::Covariance(cov); | ||||
|             // Add between factor
 | ||||
|             newFactors.emplace_shared<BetweenFactor<Pose3>>(X(key1), X(key2), relativePose, noise); | ||||
|             cout << "Add BETWEEN factor: " << key1 << " -> " << key2 << endl; | ||||
|             // Provide an initial guess if needed
 | ||||
|             if (!newValues.exists(X(key2))) { | ||||
|                 newValues.insert(X(key2), lastPose.compose(relativePose)); | ||||
|                 newTimestamps[X(key2)] = timestamp; | ||||
|             } | ||||
|         } else { | ||||
|             cerr << "Unknown factor type: " << factorType << endl; | ||||
|             continue; | ||||
|         } | ||||
| 
 | ||||
|         // Print some intermediate statistics
 | ||||
|         cout << "Before update - Graph has " << smoother.getFactors().size() | ||||
|              << " factors, " << smoother.getFactors().nrFactors() << " nr factors." << endl; | ||||
|         cout << "New factors: " << newFactors.size() | ||||
|              << ", New values: " << newValues.size() << endl; | ||||
| 
 | ||||
|         // Attempt to update the smoother with new factors and values
 | ||||
|         try { | ||||
|             smoother.update(newFactors, newValues, newTimestamps); | ||||
|             // Optional: Perform extra internal iterations if needed
 | ||||
|             size_t maxExtraIterations = 3; | ||||
|             for (size_t i = 1; i < maxExtraIterations; ++i) { | ||||
|                 smoother.update(); | ||||
|             } | ||||
|             // you may not get expected results if you use the gtsam version lower than 4.3
 | ||||
|             cout << "After update - Graph has " << smoother.getFactors().size() | ||||
|                  << " factors, " << smoother.getFactors().nrFactors() << " nr factors." << endl; | ||||
| 
 | ||||
|             // Retrieve the latest estimate
 | ||||
|             currentEstimate = smoother.calculateEstimate(); | ||||
|             if (!currentEstimate.empty()) { | ||||
|                 // Update lastPose to the last key's estimate
 | ||||
|                 Key lastKey = currentEstimate.keys().back(); | ||||
|                 lastPose = currentEstimate.at<Pose3>(lastKey); | ||||
|             } | ||||
| 
 | ||||
|             // Clear containers for the next iteration
 | ||||
|             newFactors.resize(0); | ||||
|             newValues.clear(); | ||||
|             newTimestamps.clear(); | ||||
|         } catch (const exception &e) { | ||||
|             cerr << "Smoother update failed: " << e.what() << endl; | ||||
|         } | ||||
|     } | ||||
| 
 | ||||
|     // The results of the last sliding window are saved to a g2o file for visualization or further analysis.
 | ||||
|     saveG2oGraph(smoother.getFactors(), currentEstimate, "isam", lineCount); | ||||
|     factor_file.close(); | ||||
| 
 | ||||
|     return 0; | ||||
| } | ||||
| 
 | ||||
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