CurvatureFilter.cpp

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/*
 * CurvatureFilter.cpp
 *
 *  Created on: Sep 23, 2017
 *      Author: Peter Fankhauser
 *   Institute: ETH Zurich, ANYbotics
 */

#include <grid_map_filters/CurvatureFilter.hpp>

#include <grid_map_core/grid_map_core.hpp>
#include <pluginlib/class_list_macros.h>

#include <Eigen/Dense>

using namespace filters;

namespace grid_map {

template<typename T>
CurvatureFilter<T>::CurvatureFilter()
{
}

template<typename T>
CurvatureFilter<T>::~CurvatureFilter()
{
}

template<typename T>
bool CurvatureFilter<T>::configure()
{
  if (!FilterBase < T > ::getParam(std::string("input_layer"), inputLayer_)) {
    ROS_ERROR("Curvature filter did not find parameter `input_layer`.");
    return false;
  }
  ROS_DEBUG("Curvature filter input layer is = %s.", inputLayer_.c_str());

  if (!FilterBase < T > ::getParam(std::string("output_layer"), outputLayer_)) {
    ROS_ERROR("Curvature filter did not find parameter `output_layer`.");
    return false;
  }
  ROS_DEBUG("Curvature filter output_layer = %s.", outputLayer_.c_str());

  return true;
}

template<typename T>
bool CurvatureFilter<T>::update(const T& mapIn, T& mapOut)
{
  if (!mapIn.isDefaultStartIndex()) throw std::runtime_error(
      "CurvatureFilter cannot be used with grid maps that don't have a default buffer start index.");

  mapOut = mapIn;
  mapOut.add(outputLayer_);
  auto& input = mapOut[inputLayer_];
  auto& curvature = mapOut[outputLayer_];
  const float L2 = mapOut.getResolution() * mapOut.getResolution();

  for (Eigen::Index j{0}; j < input.cols(); ++j) {
    for (Eigen::Index i{0}; i < input.rows(); ++i) {
      // http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/How_Curvature_works/00q90000000t000000/
      if (!std::isfinite(input(i, j))) continue;
      float D = ((input(i, j==0 ? j : j-1) + input(i, j==input.cols()-1 ? j : j + 1)) / 2.0 - input(i, j)) / L2;
      float E = ((input(i==0 ? i : i-1, j) + input(i==input.rows()-1 ? i : i + 1, j)) / 2.0 - input(i, j)) / L2;
      if (!std::isfinite(D)) D = 0.0;
      if (!std::isfinite(E)) E = 0.0;
      curvature(i, j) = -2.0 * (D + E);
    }
  }

  return true;
}

} /* namespace */

PLUGINLIB_EXPORT_CLASS(grid_map::CurvatureFilter<grid_map::GridMap>, filters::FilterBase<grid_map::GridMap>)