karto探秘之open_karto 第二章 --- 参数解析

 

参数说明来源于 Mapper.cpp 中的   void Mapper::InitializeParameters() 方法。

    m_pUseScanMatching = new Parameter(
        // 是否使用扫描匹配方法进行匹配
        "UseScanMatching",
        "When set to true, the mapper will use a scan matching algorithm. "
        "In most real-world situations this should be set to true so that the "
        "mapper algorithm can correct for noise and errors in odometry and "
        "scan data. In some simulator environments where the simulated scan "
        "and odometry data are very accurate, the scan matching algorithm can "
        "produce worse results. In those cases set this to false to improve "
        "results.",
        true,
        GetParameterManager());

    m_pUseScanBarycenter = new Parameter(
        // 使用scan末端点的坐标的平均值 作为一帧scan与另一帧scan距离偏差的判定
        "UseScanBarycenter",
        "Use the barycenter of scan endpoints to define distances between "
        "scans.",
        true, GetParameterManager());

    m_pMinimumTimeInterval = new Parameter(
        // 2帧有效scan间的时间间隔，不满足这个时间间隔将舍弃最新scan
        "MinimumTimeInterval",
        "Sets the minimum time between scans. If a new scan's time stamp is "
        "longer than MinimumTimeInterval from the previously processed scan, "
        "the mapper will use the data from the new scan. Otherwise, it will "
        "discard the new scan if it also does not meet the minimum travel "
        "distance and heading requirements. For performance reasons, it is "
        "generally it is a good idea to only process scans if a reasonable "
        "amount of time has passed. This parameter is particularly useful "
        "when there is a need to process scans while the robot is stationary.",
        3600, GetParameterManager());

    m_pMinimumTravelDistance = new Parameter(
        // 2帧有效scan间的距离间隔，不满足这个距离间隔将舍弃最新scan
        "MinimumTravelDistance",
        "Sets the minimum travel between scans.  If a new scan's position is "
        "more than minimumTravelDistance from the previous scan, the mapper "
        "will use the data from the new scan. Otherwise, it will discard the "
        "new scan if it also does not meet the minimum change in heading "
        "requirement. For performance reasons, generally it is a good idea to "
        "only process scans if the robot has moved a reasonable amount.",
        0.2, GetParameterManager());

    m_pMinimumTravelHeading = new Parameter(
        // 2帧有效scan间的角度间隔，不满足这个角度间隔将舍弃最新scan
        "MinimumTravelHeading",
        "Sets the minimum heading change between scans. If a new scan's "
        "heading is more than MinimumTravelHeading from the previous scan, the "
        "mapper will use the data from the new scan.  Otherwise, it will "
        "discard the new scan if it also does not meet the minimum travel "
        "distance requirement. For performance reasons, generally it is a good "
        "idea to only process scans if the robot has moved a reasonable "
        "amount.",
        math::DegreesToRadians(10), GetParameterManager());

    m_pScanBufferSize = new Parameter(
        // running scan 保存scan的个数，想要保存20米范围的雷达数据，用20/2帧雷达的最小距离值 得到个数
        "ScanBufferSize",
        "Scan buffer size is the length of the scan chain stored for scan "
        "matching. \"ScanBufferSize\" should be set to approximately "
        "\"ScanBufferMaximumScanDistance\" / \"MinimumTravelDistance\". The "
        "idea is to get an area approximately 20 meters long for scan "
        "matching. For example, if we add scans every MinimumTravelDistance == "
        "0.3 meters, then \"scanBufferSize\" should be 20 / 0.3 = 67.)",
        70, GetParameterManager());

    m_pScanBufferMaximumScanDistance = new Parameter(
        // running scan 保存 雷达数据的最大距离，第一帧与最新一帧间的距离偏差最大为20m
        "ScanBufferMaximumScanDistance",
        "Scan buffer maximum scan distance is the maximum distance between the "
        "first and last scans in the scan chain stored for matching.",
        20.0, GetParameterManager());

    m_pLinkMatchMinimumResponseFine = new Parameter(
        // response值超过这个阈值才算的上 是2个接近的scan，才能作为一个link chain
        // 多机器人协同建图时，2个机器人的scan的匹配得分高于这个值才算 接近的位姿
        "LinkMatchMinimumResponseFine",
        "Scans are linked only if the correlation response value is greater "
        "than this value.",
        0.8, GetParameterManager());

    m_pLinkScanMaximumDistance = new Parameter(
        // 在 当前scan 10m的范围内找 near chain ，之后添加边 
        "LinkScanMaximumDistance",
        "Maximum distance between linked scans.  Scans that are farther apart "
        "will not be linked regardless of the correlation response value.",
        10.0, GetParameterManager());

    //
    //    Loop Closing

    m_pLoopSearchMaximumDistance = new Parameter(
        // 在当前scan周围4米范围内寻找 可能的回环
        "LoopSearchMaximumDistance",
        "Scans less than this distance from the current position will be "
        "considered for a match in loop closure.",
        4.0, GetParameterManager());

    m_pDoLoopClosing = new Parameter(
        // 是否做回环检测
        "DoLoopClosing",
        "Enable/disable loop closure.",
        true, GetParameterManager());

    m_pLoopMatchMinimumChainSize = new Parameter(
        // 作为一个有效的 chain 的最小scan 的个数
        "LoopMatchMinimumChainSize",
        "When the loop closure detection finds a candidate it must be part of "
        "a large set of linked scans. If the chain of scans is less than this "
        "value we do not attempt to close the loop.",
        10, GetParameterManager());

    m_pLoopMatchMaximumVarianceCoarse = new Parameter(
        // 做 回环检测 时，粗 匹配的 最大的 协方差 的阈值
        "LoopMatchMaximumVarianceCoarse",
        "The co-variance values for a possible loop closure have to be less "
        "than this value to consider a viable solution. This applies to the "
        "coarse search.",
        math::Square(0.4), GetParameterManager());

    m_pLoopMatchMinimumResponseCoarse = new Parameter(
        // 做 回环检测 时，粗 匹配的 最小 响应值 的阈值
        "LoopMatchMinimumResponseCoarse",
        "If response is larger then this, then initiate loop closure search at "
        "the coarse resolution.",
        0.8, GetParameterManager());

    m_pLoopMatchMinimumResponseFine = new Parameter(
        // 做 回环检测 时，精 匹配的 最小阈值（响应值）（匹配得分）
        "LoopMatchMinimumResponseFine",
        "If response is larger then this, then initiate loop closure search at "
        "the fine resolution.",
        0.8, GetParameterManager());

    //
    //    CorrelationParameters correlationParameters;

    m_pCorrelationSearchSpaceDimension = new Parameter(
        // 匹配器使用的搜索网格的大小。搜索网格的大小将为 0.3 * 0.3
        "CorrelationSearchSpaceDimension",
        "The size of the search grid used by the matcher. The search grid will "
        "have the size CorrelationSearchSpaceDimension * "
        "CorrelationSearchSpaceDimension",
        0.3, GetParameterManager());

    m_pCorrelationSearchSpaceResolution = new Parameter(
        // 扫描匹配所用网格的分辨率 0.01m
        "CorrelationSearchSpaceResolution",
        "The resolution (size of a grid cell) of the correlation grid.",
        0.01, GetParameterManager());

    m_pCorrelationSearchSpaceSmearDeviation = new Parameter(
        // 
        "CorrelationSearchSpaceSmearDeviation",
        "The point readings are smeared by this value in X and Y to create a "
        "smoother response.",
        0.03, GetParameterManager());


    //
    //    CorrelationParameters loopCorrelationParameters;

    m_pLoopSearchSpaceDimension = new Parameter(
        // 用于回环检测的scan match的网格的初始化数据，网格大小: 8m * 8m
        "LoopSearchSpaceDimension",
        "The size of the search grid used by the matcher.",
        8.0, GetParameterManager());

    m_pLoopSearchSpaceResolution = new Parameter(
        // 用于回环检测的scan match的网格的初始化数据，网格的分辨率 0.05m
        "LoopSearchSpaceResolution",
        "The resolution (size of a grid cell) of the correlation grid.",
        0.05, GetParameterManager());

    m_pLoopSearchSpaceSmearDeviation = new Parameter(
        // 用于回环检测的scan match的网格的初始化数据，
        "LoopSearchSpaceSmearDeviation",
        "The point readings are smeared by this value in X and Y to create a "
        "smoother response.",
        0.03, GetParameterManager());

    //
    // ScanMatcherParameters;

    m_pDistanceVariancePenalty = new Parameter(
        // 扫描匹配时 偏离里程计坐标的 惩罚因子
        // kt_double distancePenalty = 1.0 - (DISTANCE_PENALTY_GAIN (0.2) * squaredDistance / m_pDistanceVariancePenalty );

        "DistanceVariancePenalty",
        "Variance of penalty for deviating from odometry when scan-matching. "
        "The penalty is a multiplier (less than 1.0) is a function of the "
        "delta of the scan position being tested and the odometric pose.",
        math::Square(0.3), GetParameterManager());

    m_pAngleVariancePenalty = new Parameter(
        // 角度偏差的惩罚因子
        "AngleVariancePenalty",
        "See DistanceVariancePenalty.",
        math::Square(math::DegreesToRadians(20)), GetParameterManager());

    m_pFineSearchAngleOffset = new Parameter(
        // 精扫描匹配的角度搜索范围 0.2度
        "FineSearchAngleOffset",
        "The range of angles to search during a fine search.",
        math::DegreesToRadians(0.2), GetParameterManager());

    m_pCoarseSearchAngleOffset = new Parameter(
        // 粗扫描匹配的角度搜索范围，20度
        "CoarseSearchAngleOffset",
        "The range of angles to search during a coarse search.",
        math::DegreesToRadians(20), GetParameterManager());

    m_pCoarseAngleResolution = new Parameter(
        // 粗扫描匹配的角度分辨率，2度
        "CoarseAngleResolution",
        "Resolution of angles to search during a coarse search.",
        math::DegreesToRadians(2), GetParameterManager());

    m_pMinimumAnglePenalty = new Parameter(
        // 角度惩罚值的最小值
        "MinimumAnglePenalty",
        "Minimum value of the angle penalty multiplier so scores do not become "
        "too small.",
        0.9, GetParameterManager());

    m_pMinimumDistancePenalty = new Parameter(
        // 距离惩罚值的最小值
        "MinimumDistancePenalty",
        "Minimum value of the distance penalty multiplier so scores do not "
        "become too small.",
        0.5, GetParameterManager());

    m_pUseResponseExpansion = new Parameter(
        // 如果最初没有找到合适的匹配项，是否增加搜索空间
        "UseResponseExpansion",
        "Whether to increase the search space if no good matches are initially "
        "found.",
        false, GetParameterManager());
  }