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
