CMake has a long-standing bug/feature (see [here](https://cmake.org/pipermail/cmake/2015-March/060204.html) and reply [here](https://cmake.org/pipermail/cmake/2015-March/060209.html)) which can mangle certain path variables by attempting to make them into relative paths if you try to set them with CACHE PATH.
Say you have your OpenCV download at `/path/on/my/computer/to/opencv/`. What actually happens is that if you try to set this variable by invoking CMAKE with `-DCMAKE_INSTALL_PREFIX=/my/desired/install/path`, what you end up is *not* `/usr/local/` and *not* `my/desired/install/path`, but instead, this monstrosity: `/path/on/my/computer/to/opencv/src/OpenCV-build//my/desired/install/path`.
That is, CMake attempts, for some reason, to turn the path that you passed into a path relative to `${CMAKE_BINARY_DIR}`. See the links I posted above: this is a known (and apparently unfixable) issue with CMake.
In OpenCV's case, among other potential issues, this leads to broken paths in `opencv_tests_config.hpp`, which can break the build or cause bizarre behaviour.
The fix for this issue, as stated in my links above, is to test that the variable hasn't been set yet with an `if(NOT DEFINED ...)` before attempting to set it. This is what I've implemented here. I admit I don't know enough about OpenCV's internals to know whether you *really* need to force the install to be in `/usr/local`, but as it stands right now you get *neither* a clean `/usr/local` path *nor* a customized `/my/desired/install/path`, but a broken mess. This change at least allows the user to customize their install directory.
In the meantime, there's a workaround for this, by explicitly defining the variable as a path with `-DCMAKE_INSTALL_PREFIX:PATH=my/desired/install/path`. But if this change can save anyone else the hours of headaches that I had today, I'll be happy.
* moved BLAS/LAPACK detection scripts from opencv_contrib/dnn to the main repository.
* trying to fix the bug with undefined symbols sgesdd_ and dgesdd_
* removed extra whitespaces; disabled LAPACK on IOS
Aravis several updates
* Fix adressing camera with id=0
* Aravis buffer property control & status added
* Modify of autoexposure algorith, ream frame ID from aravis + new properites
* Change of macro name
* VideoCapture now returns no frame on camera disconnecion
* Allow aravis-0.4 usage, proper camera object release.
- removed OpenCV_LIB_DIR* vars (they are broken and not required anymore)
- OpenCVConfig.cmake doesn't contain ANDROID/CUDA code if there is no such support
- removed OpenCV2_INCLUDE_DIRS_CONFIGCMAKE, merged into OpenCV_INCLUDE_DIRS_CONFIGCMAKE
- fix hard-coded relative paths for OpenCV_INSTALL_PATH
- removed OpenCV_TBB_ARCH
- switch OpenCVConfig.cmake into 2-level mode for Android SDK
PR #2968: cce2d998578f9c
Fixed bug which caused crash of GPU version of feature matcher in stitcher
The bug caused crash of GPU version of feature matcher in stitcher when
we use ORB features.
PR #3236: 5947519
Check sure that we're not already below required leaf false alarm rate before continuing to get negative samples.
PR #3190
fix blobdetector
PR #3562 (part): 82bd82e
TBB updated to 4.3u2. Fix for aarch64 support.
PR #3604 (part): 091c7a3
OpenGL interop sample reworked not ot use cvconfig.h
PR #3792: afdf319
Add -L for CUDA libs path to pkg-config
Add all dirs from CUDA_LIBS_PATH as -L linker options to
OPENCV_LINKER_LIBS. These will end up in opencv.pc.
PR #3893: 122b9f8
Turn ocv_convert_to_lib_name into a function
PR #5490: ec5244a
fixed memory leak in findHomography tests
PR #5491: 0d5b739
delete video readers
PR #5574
PR #5202
- added new functions from core module: split, merge, add, sub, mul, div, ...
- added function replacement mechanism
- added example of HAL replacement library
- IPP is disabled by default when compiler is mingw (couldn't make it
work)
- fixed some warnings
- fixed some `__GNUC__` version checks (for correctness and convenience)
- removed UTF-8 BOM from hough.cpp (fixes#5253)
