在Ubuntu上编译opencv3.4.2源码时，遇到下面的错误，
错误1：
/home/src/software/opencv-3.4.2/modules/stitching/include/opencv2/stitching/detail/matchers.hpp:52:42: fatal error: opencv2/xfeatures2d/cuda.hpp: No such file or directory
 #  include "opencv2/xfeatures2d/cuda.hpp"
                                          ^
compilation terminated.

解决办法1：
在/home/src/software/opencv-3.4.2/modules/stitching/CMakeLists.txt中加入：
INCLUDE_DIRECTORIES("/home/src/software/opencv-3.4.2/opencv_contrib-3.4.2/modules/xfeatures2d/include")

解决办法2：
根据报错信息，打开/home/src/software/opencv-3.4.2/modules/stitching/include/opencv2/stitching/detail/matchers.hpp文件，将52行
#include "opencv2/xfeatures2d/cuda.hpp"
替换成  #include "/home/src/software/opencv-3.4.2/opencv_contrib-3.4.2/modules/xfeatures2d/include/opencv2/xfeatures2d/cuda.hpp"

重新编译即可。

错误2：
/home/src/software/opencv-3.4.2/opencv_contrib-3.4.2/modules/xfeatures2d/src/boostdesc.cpp:693:46: fatal error: boostdesc_bgm.i: No such file or directory
           #include "boostdesc_bgm.i"
                                              ^
compilation terminated.

解决办法：
应该是boostdesc_bgm.i文件下载失败了，需要手动下载，在/home/src/software/opencv-3.4.2/build路径下找到CMakeDownloadLog.txt，打开后搜索”boostdesc_bgm.i“，复制其下载地址到网页可以看到源码，直接拷贝源码并存为同名文件，把它放在
/home/src/software/opencv-3.4.2/opencv_contrib-3.4.2/modules/xfeatures2d/src
路径下，
以下这些文件也都需要手动下载：
boostdesc_bgm.i
boostdesc_bgm_bi.i
boostdesc_bgm_hd.i
boostdesc_lbgm.i
boostdesc_binboost_064.i
boostdesc_binboost_128.i
boostdesc_binboost_256.i
vgg_generated_120.i
vgg_generated_64.i
vgg_generated_80.i
vgg_generated_48.i
把上述文件放置在上述指定路径下后，直接make重新编译即可
注：opencv源码编译教程和其它报错，大家可以看我之前的博客，祝大家安装顺利！