How do I remove openCV - opencv

I am trying to remove opencv fully from my system. I was trying to learn ROS, while in tutorials I faced an issue. After creating empty workspace I invoke
catkin_make
It gives an common error, I searched and asked around in answers.ros
here is the link of the question
I think I found out the problem was opencv libraries which I had build before installing ROS-Noetic, creating the error, I searched around how to remove opencv, but non of the answers totally remove opencv without removing my opencv names files.
Is there a common solution on how to remove opencv?
Ubuntu 20.04
ROS Noetic

Best way if you installed opencv from source and still have the build directory, simply go there and call make uninstall. Another solution is to delete all opencv related files as you already know and suggested in many other similar questions like this. You could also try to use synaptic package manager if you installed using a package.
I suggest for the future to install development libraries a custom folder, so it will be just a matter of deleting that folder if something goes wrong. In this way you can also have different opencv versions in your system, this is how I do.

Related

Rust binding for OpenCV seems to be missing the face module

I'm using opencv as OpenCV bindings for rust and I'm trying to implement an EigenFaceRecogniser system. On docs.rs, the opencv::face module is listed inside the opencv crate. However, when I build my code, I get the error:
could not find face in opencv
I'm not really sure what's causing this as the face module is clearly listed in the documentation but for some reason I cannot use it. If anybody who has used these bindings before or knows anything about what could be going wrong could help, it would be appreciated.
I'm using OpenCV version 4.5.1.
The solution was to enable the contrib feature for the opencv package.
While I was writing the above question, I stumbled across this post asking about OpenCV having no face module in python. The solution to that question was to install the opencv-contrib-python package so I tried enabling the contrib feature in the opencv crate and it compiled. I thought I'd post this question anyway just in case somebody else was having this issue.

How to get the ImageMagick library working with Swift 4/iOS 11?

I'm trying to get ImageMagick to work in my iOS project. Unfortunately everything I have tried so far has not worked.
Cocoapods
The most obvious approach would be to use the cocoapod. Unfortunately after installing the cocoapod there doesn't appear to be anything exposed to swift to import. Maybe I'm missing something obvious and if anyone has any ideas that would be great. Unfortunately the documentation is lacking as far as specific examples go.
Static library - approach #1
The official ImageMagick docs provide some instructions to compile the latest version of ImageMagick and include a static library in your Xcode project. Unfortunately the first step of the instructions requires running a bash script imagemagick_compile.sh which I cannot find. Once again I could be missing something obvious.
Static library - approach #2
After some additional searching I found the ~Claudio guy which the ImageMagick docs mention as the maintainer of the iOS version of ImageMagick. He has a repo with similar instructions as provided by ImageMagick but this repo includes a bash script to compile and generate a static library of ImageMagick. I tried running the script directly ./all.sh 6.8.8-9 but soon realized I hadn't setup a build directory they way his instructions outlined and I got stuck getting libpng installed correctly.
Static library - approach #3
The same repo with the instructions to compile and generate a static library also includes an old sample iOS project with a static library already included for an older version of ImageMagick. This just about worked except the ImageMagick library has a class Timer that clashes with the Timer class provided by Swift4/iOS so I couldn't get my project to compile using this static library of ImageMagick.
ImageMagick iOS Questions on SO
There are a handful of other questions on Stack Overflow that deal with running ImageMagick on iOS so I know other people have done it but nothing very recent. If anyone has any ideas that would be greatly appreciated, thanks!
Un-answered question on how to use ImageMagick on iOS: ImageMagick iOS image Potentially useful comment that includes some of the same links that I provided above.
Someone already using ImageMagick for iOS but gives no details on how it was implemented: ImageMagick circular dstortion on iOS
Un-answered question from someone already using ImageMagick in their app: Ios - ImageMagick - No Image Created after Distortion
More recent question related to warnings using the cocoapod version: iOS: ImageMagick compiler warnings in Xcode
Other questions: https://stackoverflow.com/search?q=imagemagick+ios Unfortunately I haven't found any of these that have helped.
To integrate ImageMagick into iOS you will need to do the following:
Install the library available here https://www.imagemagick.org/download/iOS/
You will need a Swift-Objective-C bridging header that includes:
#import "ImageMagick.h"
#import "MagickWand.h"
You will need to modify any functions that reference Timer to Foundation.Timer, this will resolve any conflicts with the ImageMagick library
You will need to add under Your target > Build Phases > Link Binary With Libraries > "libxml2.tbd".
Hope this helps

Cannot compile OpenCV for iOS with nonfree module

I'm attempting to compile the OpenCV framework for iOS using the nonfree module. Right now, I'm not able to compile the OpenCV framework, period. I would use the stock iOS opencv2.framework download from the website, except it doesn't include the nonfree module that I need for my project. I've been following the instructions as prescribed here:
http://answers.opencv.org/question/61663/how-to-make-opencv2framework-with-opencv_contrib/
as these appear they might be out of date
http://docs.opencv.org/2.4/doc/tutorials/introduction/ios_install/ios_install.html
https://github.com/Itseez/opencv/issues/4712
However, when I run the command from a folder outside the building directories "python opencv-master/platforms/ios/build_framework.py --contrib opencv_contrib-master ios_contrib" it spits out the following error:
http://pastebin.com/LUep8Tdw
The error doesn't mean much to me. I thought at first it was related to me building it inside the same directory as opencv, but I tried it outside of it and it still failed. Any thoughts? I've tried everything I can possibly think of, and done a bunch of research without coming up with anything.
It appears there's some issue with one of the modules in opencv_contrib. I'm not sure what it is, but I was using version 3.0.0-rc-1. The way I got around it was by moving specific modules from the module folder in the contrib folder into the regular opencv directory's modules folder and then compiling the framework from scratch.

Linking Header File with Main.Cpp file in Codeblocks

I am trying to use codeblocks to compile the code available here
The thing is every time I try to build and run, I run into the following error:
|/.../head_pose_estimation/opencv2/core/core.hpp|48|fatal error: opencv2/core.hpp: No such file or directory
Does anyone know how I can fix this? Thank you!
You do not have the pre-built (compiled) version of OpenCV, what you currently have are the source files. If you want to do something special with OpenCV (Target/GPU SUpport etc) then you will need to build the framework using an appropriate guide.
If however you simply want to use OpenCV in the most common way then download the pre-built libraries from the OpenCV.org website.
NOTE:
If you are using OpenCV with MinGW compiler, I do not remember if the pre-built is actually pre-built for MinGW. (I dont think they do) In this case you will HAVE to built the libraries. You can find a guide here

Does OpenCV need to be compiled before using?

I'm trying to install OpenCV on Windows. Following are how I installed it:
Download OpenCV 2.4.2.exe from sourceforge.
unarchived it.
open Eclipse CDT.
Add C:/opencv/include/opencv to "Includes"
Add opencv_highgui, opencv_core, opencv_ml... to "Libraries"
Create a small project and compiled it.
The compiler complained about "opencv2/core/core_c.h:No such file or directory"...
I remember that when I install OpenCV on Ubuntu, I did compiled the project (it took quite a bit of time). Do I have to do the same thing on Windows? Or is any other thing causing this error?
Thanks.
You should add correct directories to includes.
Since you added C:/opencv/include/opencv, there is no way for compiler to find C:/opencv/include/opencv2/core/core.h.
I believe you should enter C:/opencv/include/ to includes directories as well.

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