Python bindings don't respect CMAKE_INSTALL_PREFIX

[m-elwin]

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Required Info
Camera Model	Any
Firmware Version	N/A}
Operating System & Version	{Linux}
Kernel Version (Linux Only)	(e.g. 4.14.13)
Platform	PC
SDK Version	{ 2.50.0 }
Language	{python }
Segment	{Robot/Smartphone/VR/AR/others }

Issue Description

When configuring a build with -DBUILD_PYTHON_BINDINGS=ON, the generated
python libraries are always installed relative to / (e.g., /usr/lib/python3.10/dist-packages), regardless of the value of CMAKE_INSTALL_PREFIX.

Specifying -DPYTHON_INSTALL_DIR manually works around this issue.

I believe the issue is related to how the Python install directory is determined.
In wrappers/python/CMakeLists.txt:64, PYTHON_INSTALL_DIR is set to ${Python_SITEARCH}, which I believe is always an absolute path.

I think the code used for CMake Version <3.12 may not have this issue.

[MartyG-RealSense]

Thanks very much @m-elwin for highlighting this CMake issue to the RealSense community and advising about a manual workaround!

[MartyG-RealSense]

Case closed due to no further comments received. Thanks again @m-elwin for sharing your workaround!

[maloel]

@m-elwin
First, thanks for your contribution.
But I have to ask, why do you want to override the install directory?
Installation is supposed to put the compiled code in a place where a python import command would see it. Python itself sets this folder and, according to the docs, that's the folder that should be used.

Do you have two different Python installations? Is CMake finding the wrong Python executable?

[m-elwin]

Wanted to install under my home directory instead of system python directory (which requires root).