trying to use with pcl::PointXYZI

[DingFeng9313]

Hi, I am trying to use pico_tree with pcl::pointXYZI

looks like I should use both custom spacetraits and custom point. My custom SpaceTraits are as follows:

template <>
struct PointTraits<pcl::PointXYZI> {
  using PointType = pcl::PointXYZI;
  using ScalarType = float;
  // Spatial dimension. Set to pico_tree::kDynamicSize when the dimension is
  // only known at run-time.
  static std::size_t constexpr Dim = 3;

  // Returns a pointer to the coordinates of the input point.
  inline static float const* data(pcl::PointXYZI const& point) { return point.data; }

  // Returns the number of coordinates or spatial dimension of each point.
  inline static constexpr std::size_t size(pcl::PointXYZI const&) { return Dim; }
};

// Provides an interface for an std::deque<std::array>.
template <typename Scalar_, std::size_t Dim_>
struct SpaceTraits<std::deque<pcl::PointXYZI>> {
  using SpaceType = std::deque<pcl::PointXYZI>;
  using PointType = pcl::PointXYZI;
  using ScalarType = Scalar_;
  // Spatial dimension. Set to pico_tree::kDynamicSize when the dimension is
  // only known at run-time.
  static std::size_t constexpr Dim = Dim_;

  // Returns a point from the input space at the specified index.
  template <typename Index_>
  inline static PointType const& PointAt(
      SpaceType const& space, Index_ const index) {
    return space[static_cast<std::size_t>(index)];
  }

  // Returns number of points contained by the space.
  inline static std::size_t size(SpaceType const& space) {
    return space.size();
  }

  // Returns the number of coordinates or spatial dimension of each point.
  inline static constexpr std::size_t sdim(SpaceType const&) { return Dim; }
};

But it reports

 error: template parameters not deducible in partial specialization:
 struct SpaceTraits<std::deque<pcl::PointXYZI>>

Is it possible to use pico_tree this way? How can I use it with pcl library?

[Jaybro]

You can definitely use pico_tree with PCL. At first glance your custom PointTraits are fine, except that I don't see a namespace:

namespace pico_tree {

template <>
struct PointTraits<pcl::PointXYZI> {
  ...
};

}  // namespace pico_tree

However, your custom SpaceTraits needs a few changes:

namespace pico_tree {

// pcl::PointXYZI doesn't require template arguments, so we leave the template
// parameters for SpaceTraits empty. This results in a full template
// specialization for std::deque<pcl::PointXYZI>.
template <>
struct SpaceTraits<std::deque<pcl::PointXYZI>> {
  ...
  using ScalarType = float;
  static std::size_t constexpr Dim = 3;
  ...
};

}  // namespace pico_tree

[Jaybro]

Note that I would recommend using an std::vector over an std::deque because it would be faster. All you have to do is #include <pico_tree/vector_traits.hpp> and add your custom PointTraits<pcl::PointXYZI>.

If you really want to work with std::deque then here is a generic SpaceTraits<std::deque<Point_>> that will work for any point type Point_ supported by a PointTraits<Point_>:

namespace pico_tree {

// Provides an interface for an std::deque<Point_>.
template <typename Point_>
struct SpaceTraits<std::deque<Point_>> {
  using SpaceType = std::deque<Point_>;
  using PointType = Point_;
  using ScalarType = typename PointTraits<Point_>::ScalarType;
  static std::size_t constexpr Dim = PointTraits<Point_>::Dim;

  // It is not reliably possible to get the spatial dimension of an std::deque.
  // I.e., when the point set is empty.
  static_assert(
      Dim != kDynamicSize, "DEQUE_OF_POINT_DOES_NOT_SUPPORT_DYNAMIC_DIM");

  // Returns a point from the input space at the specified index.
  template <typename Index_>
  inline static PointType const& PointAt(
      SpaceType const& space, Index_ const index) {
    return space[static_cast<std::size_t>(index)];
  }

  // Returns number of points contained by the space.
  inline static std::size_t size(SpaceType const& space) {
    return space.size();
  }

  // Returns the number of coordinates or spatial dimension of each point.
  inline static constexpr std::size_t sdim(SpaceType const&) { return Dim; }
};

}  // namespace pico_tree

[DingFeng9313]

Thanks a lot. That solved my problem. I copied code from example files "kd_tree_custom_space_type.cpp", that is why it is std::deque. Initially I want to use std::vector.

Thanks again.