opencv-contrib在cmake中出现下载错误的解决。

opencv-contrib的这个master版本Latest commit 23c0256 Apr 12, 2017

在cmake中会出现下载错误，导致config失败。

看cmake源代码知道ocv_download这个函数在使用的时候，错把PACKAGE写成filename.

修改后再次config,generate成功。

D:\opencv\opencv_contrib\modules\dnn\cmake\OpenCVFindLibProtobuf.cmake 32 行改为  ocv_download(PACKAGE "protobuf-cpp-3.1.0.tar.gz"

D:\opencv\opencv_contrib\modules\dnn_modern\CMakeLists.txt 20行改为 ocv_download(PACKAGE "v1.0.0a3.tar.gz"

D:\opencv\opencv_contrib\modules\xfeatures2d\cmake\download_boostdesc.cmake 22行改为  ocv_download(PACKAGE ${name_${id}}

D:\opencv\opencv_contrib\modules\xfeatures2d\cmake\download_vgg.cmake 16行改为 ocv_download(PACKAGE ${name_${id}}