point_coding.h

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#pragma once
 
#include <algorithm>
#include <iostream>
#include <vector>
 
namespace pcl
{
namespace octree
{
/** \brief @b PointCoding class
  * \note This class encodes 8-bit differential point information for octree-based point cloud compression.
  * \note typename: PointT: type of point used in pointcloud
  * \author Julius Kammerl (julius@kammerl.de)
  */
template<typename PointT>
class PointCoding
{
    // public typedefs
    using PointCloud = pcl::PointCloud<PointT>;
    using PointCloudPtr = typename PointCloud::Ptr;
    using PointCloudConstPtr = typename PointCloud::ConstPtr;
 
  public:
    /** \brief Constructor. */
    PointCoding () = default;
 
    /** \brief Empty class constructor. */
    virtual
    ~PointCoding () = default;
 
    /** \brief Define precision of point information
      * \param precision_arg: precision
      */
    inline void
    setPrecision (float precision_arg)
    {
      pointCompressionResolution_ = precision_arg;
    }
 
    /** \brief Retrieve precision of point information
      * \return precision
      */
    inline float
    getPrecision ()
    {
      return (pointCompressionResolution_);
    }
 
    /** \brief Set amount of points within point cloud to be encoded and reserve memory
      * \param pointCount_arg: amounts of points within point cloud
      */
    inline void
    setPointCount (unsigned int pointCount_arg)
    {
      pointDiffDataVector_.reserve (pointCount_arg * 3);
    }
 
    /** \brief Initialize encoding of differential point */
    void
    initializeEncoding ()
    {
      pointDiffDataVector_.clear ();
    }
 
    /** \brief Initialize decoding of differential point */
    void
    initializeDecoding ()
    {
      pointDiffDataVectorIterator_ = pointDiffDataVector_.begin ();
    }
 
    /** \brief Get reference to vector containing differential color data */
    std::vector<char>&
    getDifferentialDataVector ()
    {
      return (pointDiffDataVector_);
    }
 
    /** \brief Encode differential point information for a subset of points from point cloud
      * \param indexVector_arg indices defining a subset of points from points cloud
      * \param referencePoint_arg coordinates of reference point
      * \param inputCloud_arg input point cloud
      */
    void
    encodePoints (const Indices& indexVector_arg, const double* referencePoint_arg,
                  PointCloudConstPtr inputCloud_arg)
    {
      // iterate over points within current voxel
      for (const auto& idx: indexVector_arg)
      {
        unsigned char diffX, diffY, diffZ;
 
        // retrieve point from cloud
        const PointT& idxPoint = (*inputCloud_arg)[idx];
 
        // differentially encode point coordinates and truncate overflow
        diffX = static_cast<unsigned char> (std::max (-127, std::min<int>(127, static_cast<int> ((idxPoint.x - referencePoint_arg[0])  / pointCompressionResolution_))));
        diffY = static_cast<unsigned char> (std::max (-127, std::min<int>(127, static_cast<int> ((idxPoint.y - referencePoint_arg[1])  / pointCompressionResolution_))));
        diffZ = static_cast<unsigned char> (std::max (-127, std::min<int>(127, static_cast<int> ((idxPoint.z - referencePoint_arg[2])  / pointCompressionResolution_))));
 
        // store information in differential point vector
        pointDiffDataVector_.push_back (diffX);
        pointDiffDataVector_.push_back (diffY);
        pointDiffDataVector_.push_back (diffZ);
      }
    }
 
    /** \brief Decode differential point information
      * \param outputCloud_arg output point cloud
      * \param referencePoint_arg coordinates of reference point
      * \param beginIdx_arg index indicating first point to be assigned with color information
      * \param endIdx_arg index indicating last point to be assigned with color information
      */
    void
    decodePoints (PointCloudPtr outputCloud_arg, const double* referencePoint_arg, uindex_t beginIdx_arg,
                  uindex_t endIdx_arg)
    {
      assert (beginIdx_arg <= endIdx_arg);
 
      const uindex_t pointCount = endIdx_arg - beginIdx_arg;
 
      // iterate over points within current voxel
      for (uindex_t i = 0; i < pointCount; i++)
      {
        // retrieve differential point information
        const unsigned char& diffX = static_cast<unsigned char> (*(pointDiffDataVectorIterator_++));
        const unsigned char& diffY = static_cast<unsigned char> (*(pointDiffDataVectorIterator_++));
        const unsigned char& diffZ = static_cast<unsigned char> (*(pointDiffDataVectorIterator_++));
 
        // retrieve point from point cloud
        PointT& point = (*outputCloud_arg)[beginIdx_arg + i];
 
        // decode point position
        point.x = static_cast<float> (referencePoint_arg[0] + diffX * pointCompressionResolution_);
        point.y = static_cast<float> (referencePoint_arg[1] + diffY * pointCompressionResolution_);
        point.z = static_cast<float> (referencePoint_arg[2] + diffZ * pointCompressionResolution_);
      }
    }
 
  protected:
    /** \brief Pointer to output point cloud dataset. */
    PointCloudPtr output_{nullptr};
 
    /** \brief Vector for storing differential point information  */
    std::vector<char> pointDiffDataVector_;
 
    /** \brief Iterator on differential point information vector */
    std::vector<char>::const_iterator pointDiffDataVectorIterator_;
 
    /** \brief Precision of point coding*/
    float pointCompressionResolution_{0.001f};
};
 
} // namespace octree
} // namespace pcl
 
#define PCL_INSTANTIATE_ColorCoding(T) template class PCL_EXPORTS pcl::octree::ColorCoding<T>;