Ogre.h cannot be found about opencv_contrib

[LiChao1998]

Thank you for your answer, and I will close this issue since I can go to the forum.

[Kumataro]

Hello, OpenCV3 has been deprecated already, so please could you update to OpenCV4 ?(And OpenCV 3.4.0 is too old).

OpenCV try to find OGRE package. However between 3.4(including 3.4.0 tag) and 4.x branch, its CMake scripts are slightly changing. And OGRE version is important, however there are no information. Please could you share ?

4.x

opencv_contrib/modules/ovis/CMakeLists.txt

Lines 1 to 3 in ba5c23c

	set(the_description "OGRE 3D Visualiser.")
	find_package(OGRE QUIET CONFIG)

3.4

opencv_contrib/modules/ovis/CMakeLists.txt

Lines 1 to 3 in f852576

	set(the_description "OGRE 3D Visualiser.")
	find_package(OGRE 1.10 QUIET)

3.4.0

opencv_contrib/modules/ovis/CMakeLists.txt

Lines 1 to 3 in 81ca8da

	set(the_description "OGRE 3D Visualiser.")
	find_package(OGRE 1.10 QUIET)

---

In your environments, OpenCV detected OGRE package (so ovis module is available.)
pkg-config should be suggest OGRE include path and OGRE libraries.
However your compiler log shows include path is missing. I think library may be missing too. It is strange a little.

Could you try to run standalone pkg-config to find OGRE ?

pkg-config OGRE --modversion --cflags --libs

And if possible, please could you try to get log of cmake ... after Found OGRE ?

[LiChao1998]

Yes I can find the OGRE, and the version is 1.12.1.

This is the CMakeOutput.log when I run cmake .. for my test.cpp above.
CMakeOutput.log
Actually, I am trying to run an old repo, so OpenCV 4.x might be too new. BTW, I found that after I change the version of opencv and opencv_contrib to 3.3.0, the errors were strangely gone.

[LiChao1998]

Although OpenCV 3.3 is enough to run the repo, I wonder why the error occurs when using the version 3.4.0.

[Kumataro]

Yes I can find the OGRE, and the version is 1.12.1.

Maybe you use not official release from ubuntu distributors.

(For image)

I'm sorry we have to separate --modversion and --cflags --libs options.

kmtr@ubuntu:~$ pkg-config OGRE --modversion
1.9.0
kmtr@ubuntu:~$ pkg-config OGRE --cflags --libs
-pthread -I/usr/include/OGRE -lOgreMain -lpthread

This is the CMakeOutput.log when I run cmake .. for my test.cpp above.

Necessary information is console log of cmake -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules .. .
You should remove your build folder and clear at perfectory before this operation.

Actually, I am trying to run an old repo, so OpenCV 4.x might be too new.

This is OpenCV bug tracking, not Q&A forum. If you want to ask question, please use https://forum.opencv.org/
And if you want to use old OpenCV which is out of supporting,
we cannot help you in here, so it is better to close this "question" issue.