从零开始解决ubuntu2204，pcl-1.8 编译中报错的问题，cmake-gui编译

1.编译pcl时候报错，

kdtree is required, but flann not found

2.然后下载了flann，编译flann是报错
按照步骤编译的时候会报错，错误如下：
CMake Eroor at src/cpp/CMakeLists.txt:86 (add_library):
No SOURCES given to target: flann
CMake Eroor at src/cpp/CMakeLists.txt:32 (add_library):
No SOURCES given to target: flann_cpp
直到看到这个网页
https://stackoverflow.com/questions/50763621/building-flann-with-cmake-fails
直到原来是本身的问题，按照里面写的修改方法，先创建一个空的文件，然后加入到库中就行了，具体是：
首先

touch src/cpp/empty.cpp
然后在src/cpp/CMakeLists.txt中将

add_library(flann_cpp SHARED "") and add_library(flann SHARED "")
代替为

add_library(flann_cpp SHARED empty.cpp) and add_library(flann SHARED empty.cpp)

2.编译boost,官网直接下，下载下来直接编译：

①  sudo ./bootstrap.sh --prefix=/home/lib
②  sudo ./b2 install cxxflags="-std=c++14"
直接按照上面位置命令编译，正常情况下会编译通过，直接生成库，但是在编译pcl时发现问题（问题后面说），pcl编译不过然后倒回来发现boost编译时有问题，却库，缺iosstream.so这个库，查编译过程发现，编译中有报错：fatal error: bzlib.h: No such file or directory，解决报错问题：

sudo apt-get install libbz2-dev

安装完libbz后在编译，按照①②步骤重新编一编发现一切正常，会生成iosstream.so，boost编译完成。

3.编译pcl,用camke_gui编译（有点坑，不会提示boost相关的东西），直接编会报错：Could NOT find Boost (missing: iostreams)（就是上面提到的错），此时需要人为手动配置boost路径，打开pcl/cmake/pcl_find_boost.cmake这个文件，然后在里面添加boost和版本号，

set(Boost_LIBRARY_DIR /*/boost_1_61_0/boost_1_61/lib)
set(Boost_INCLUDE_DIR /*/boost_1_61_0/boost_1_61/include)

增加上面两句后保存，然后再编译，

编译过程中报错：*/pcl-pcl-1.8.0/filters/src/frustum_culling.cpp:44:1:   required from here
/usr/include/eigen3/Eigen/src/Core/Dot.h:75:3: error: static assertion failed: YOU_TRIED_CALLING_A_VECTOR_METHOD_ON_A_MATRIX
   75 |   EIGEN_STATIC_ASSERT_VECTOR_ONLY(OtherDerived)
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

查了半天发现是pcl-1.8自己的问题，不过这个问题在，pcl-1.10以后被修改了，可以参考github的上的解释：https://github.com/PointCloudLibrary/pcl/pull/2786/commits/3eeca19fda82a6d393f3c6bd09d2331ad60ee53c

错误一  针对pcl1.8所报错误，修改如下：找到：pcl-1.8/filters/include/pcl/filters/impl/frustum_culling.hpp,打开后将原来的：（0，0，3，1）改成<3,1>(0,0),其他以此类推：将所有的（i，j，3，1）改成<3,1>(i，j)，切记这个文件里的所有的都要改。具体如下：

 Eigen::Vector3f view = camera_pose_.block <3, 1> (0, 0);//(0, 0, 3, 1);    // view vector for the camera  - first column of the rotation matrix
  Eigen::Vector3f up = camera_pose_.block <3, 1> (0, 1);//(0, 1, 3, 1);      // up vector for the camera    - second column of the rotation matix
  Eigen::Vector3f right = camera_pose_.block <3, 1> (0, 2);//(0, 2, 3, 1);   // right vector for the camera - third column of the rotation matrix
  Eigen::Vector3f T = camera_pose_.block <3, 1> (0, 3);//(0, 3, 3, 1);       // The (X, Y, Z) position of the camera w.r.t origin
 

错误二  针对对编译报错类型不匹配问题：/pcl-pcl-1.8.0/segmentation/include/pcl/segmentation/plane_coefficient_comparator.h:144:17: error: invalid initialization of reference of type ‘std::vector<float>&’ from expression of type ‘const boost::shared_ptr<std::vector<float> >’
  144 |         return (plane_coeff_d_);

找到文件plane_coefficient_comparator.h，做如下修改：

 //const std::vector<float>&
      boost::shared_ptr<std::vector<float>> getPlaneCoeffD () const
      {
        return (plane_coeff_d_);
      }

将const std::vector<float>&改为boost::shared_ptr<std::vector<float>>或者

将 return (plane_coeff_d_);改为 return (*plane_coeff_d_);都可以

错误三    /pcl-pcl-1.8.0/surface/include/pcl/surface/impl/bilateral_upsampling.hpp:121:51: error: cannot convert ‘Eigen::internal::enable_if<true, Eigen::IndexedView<Eigen::Matrix<float, -1, 1>, float, Eigen::internal::SingleRange> >::type’ {aka ‘Eigen::IndexedView<Eigen::Matrix<float, -1, 1>, float, Eigen::internal::SingleRange>’} to ‘float’ in initialization 121 |

float val_exp_rgb = val_exp_rgb_vector(d_color); | ~~~~~~~~~~~~~~~~~~^~~~~~~~~ | | | Eigen::internal::enable_if<true, Eigen::IndexedView<Eigen::Matrix<float, -1, 1>, float, Eigen::internal::SingleRange> >::type {aka Eigen::IndexedView<Eigen::Matrix<float, -1, 1>, float, Eigen::internal::SingleRange>}

将float val_exp_rgb = val_exp_rgb_vector(d_color);

改为float val_exp_rgb = val_exp_rgb_vector(int(d_color)）；

错误四：    /usr/bin/ld: ../../lib/libpcl_kdtree.so.1.8.1: undefined reference to `LZ4_resetStreamHC'
/usr/bin/ld: ../../lib/libpcl_kdtree.so.1.8.1: undefined reference to `LZ4_setStreamDecode'
/usr/bin/ld: ../../lib/libpcl_kdtree.so.1.8.1: undefined reference to `LZ4_decompress_safe'
/usr/bin/ld: ../../lib/libpcl_kdtree.so.1.8.1: undefined reference to `LZ4_decompress_safe_continue'
/usr/bin/ld: ../../lib/libpcl_kdtree.so.1.8.1: undefined reference to `LZ4_compress_HC_continue'
collect2: error: ld returned 1 exit status
make[2]: *** [visualization/tools/CMakeFiles/pcl_viewer.dir/build.make:236: bin/pcl_viewer] Error 1
make[1]: *** [CMakeFiles/Makefile2:1631: visualization/tools/CMakeFiles/pcl_viewer.dir/all] Error 2

解决：/pcl/build/kdtree/CMakeFiles/pcl_kdtree.dir/下的link.txt里在末尾写上：-llz4

错误五  ： /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/local-search.hh:83:7: error: ISO C++17 does not allow dynamic exception specifications
   83 |       throw(no_moves_error);
      |       ^~~~~
/home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/local-search.hh:110:3: error: ISO C++17 does not allow dynamic exception specifications
  110 |   throw(no_moves_error)
      |   ^~~~~
In file included from /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/mets.hh:150,
                 from /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/hv/hv_go.h:14,
                 from /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/impl/hv/hv_go.hpp:40,
                 from /home/zc/Documents/pcl-pcl-1.8.1/recognition/src/hv/hv_go.cpp:37:
/home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/tabu-search.hh:245:7: error: ISO C++17 does not allow dynamic exception specifications
  245 |       throw(no_moves_error);
      |       ^~~~~
/home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/tabu-search.hh:404:3: error: ISO C++17 does not allow dynamic exception specifications
  404 |   throw(no_moves_error)
      |   ^~~~~
In file included from /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/mets.hh:151,
                 from /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/hv/hv_go.h:14,
                 from /home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/impl/hv/hv_go.hpp:40,
                 from /home/zc/Documents/pcl-pcl-1.8.1/recognition/src/hv/hv_go.cpp:37:
/home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/simulated-annealing.hh:125:7: error: ISO C++17 does not allow dynamic exception specifications
  125 |       throw(no_moves_error);
      |       ^~~~~
/home/zc/Documents/pcl-pcl-1.8.1/recognition/include/pcl/recognition/3rdparty/metslib/simulated-annealing.hh:224:3: error: ISO C++17 does not allow dynamic exception specifications
  224 |   throw(no_moves_error)
解决办法：注释掉throw(no_moves_error)即可，由于c++17不支持这个报错