I need to use the connected component labeling algorithm on an image in a C++ application. I can implement that myself, but I was trying to use Boost's union-find/disjoint sets implementation since it was mentioned in the union-find wiki article.
I can't figure out how to create the disjoint_sets object so that it'll work with the image data I have (unsigned shorts). What am I missing? The examples in the Boost documentation aren't making any sense to me. Do I need all the extra Graph mumbo-jumbo in those examples when I have an image? OR, is there already an OpenCV connected component labeling implementation. Currently we're using OpenCV 1.1pre1 and Boost 1.37.
Surprisingly, there is no CCL in OpenCV. However, there is a workaround that is described in the reference manual. See the example for cvDrawContours. When I tried to use it, I had some strange behaviour on first and last rows and columns of an image, but I probably did something wrong.
An alternative way is to use cvBlobs library.
We ended up writing the algorithms for CCL and Union-Find ourselves using the descriptions found on Wikipedia and elsewhere. It seemed easier and faster than adding another library to our application just for this purpose.
Another possibility is to use the source codes provided provided by Ali Rahimi, and you can have a look at this.
I was able to use disjoint_sets of the boost library for the connected component labeling.
But to test, I was trying to create an image with pixel intensities having the value same as its label.
This led to the problem which I haven't been able to handle yet. Have a look at the thread.
Related
I am currently in the process of learn c++ and I have decided to make a simple program that takes a .png file and exports the link inside it. I have looked it up and discovered ZXing but I still can't figure out how to implement it easily.
The ones I've found consists of scanning using webcam etc instead of a very simple version.
First, you need a library to read the images. CImg is good, it is a header only library build on top of the base libraries for the different images format: https://cimg.eu/
Assuming the image is a clean QR code you can skip the complex computer vision recognition part.
For the decoding part I am not sure, I don't know ZXing but it looks like the c++ port is no longer maintained anyway. Still, once you have the clean image it should not be a problem to use it.
You might want to have a look at the most recent c++ port of ZXing: https://github.com/nu-book/zxing-cpp
The project includes a trivial example application that does exactly what you want.
I need to use OpenCV with uEye Ethernet Camera. The problem is that I wasn't finding some useful tips regarding some example codes.
The source code provided with the installation is really linked to MFC stuff which is not what I want. It's really complicated to get rid of that, it was causing me so much problems (CWnd, Afx, Dialogs...)
I would like to read some frames from the camera and record some snapshots.
You can find the whole SDK description here: https://en.ids-imaging.com/manuals-ueye-software.html
Just simply make and account and you can access it. The documentation is really good.
I found this document in the internet
http://master-ivi.univ-lille1.fr/fichiers/Cours/uEye_SDK_manual_enu.pdf
How can I, programmatically, draw a KML-file (routing information on a map) onto a map and then save the result to a .png-file?
What I try to accomplish: a program of mine (written in C++) produces a route. Now I would like this program to emit a .png-file instead with the route draw on it.
I've looked into the google maps api as well as others (e.g. cartagen) but google maps is java-script oriented and cartagen produces html5 output.
Probably you can use Qt Framework to achive this.
It has great XML support so it should be easy to read KML.
It has support for drawing simple shapes.
It has support for PNGs too.
There is also library called libkml - it can probably help you with manipulating with KML files.
I highly doubt if there is any "Ready to Use" solution.
is there a DWT (discrete wavelet transform ) function in opencv ?? else if anyone have link of its implementation in c++
No, I don't believe OpenCV has that functionality.
This page might be useful.
It appears that openCV does not have an implementation of the DWT algorithm, but a quick google search turns up two results which may be relevant.
First is a result from Koders code search, which is an implementation designed to process MPEG4 frames for an image decoding program.
There is also a google code project, wavelet1d which is a version designed to process a 1d array of data.
You may be able to use those two implementations to build your own suitable for your uses?
i'm developing some kind of heuristics for a variation of the vehicle-routing-problem in C++.
After generating a solution, i want to plot this solution. The solution is a composite of various tours, all starting and ending at a common depot.
Therefore i have a vertex-set with all the coordinates and edges defined by two vertex-id's each. Furthermore i have all the distances between vertex-pairs of course.
It would be helpful to plot this in an extra-window opening in my program, but writing a plot to a graphics-file should be okay too.
What is an easy way to plot this? How would you tackle this?
First i tried to look for common graph-visualization packages (graphviz, tulip, networkx (python)), but i realized that all of them are specialized at graph-layouting (when there are no coordinates). Correct me when i'm wrong.
I don't know if it is possible to tell these packages that i already have the coordinates, helping the layouting-algorithms.
Next thing i tried is the CGAL library with geomview output -> no luck until now -> ubuntu crashes geomview.
One more question: Is it a better idea to use some non-layouting 2d-plot-libraries risking a plot, which isn't really good to view at (is there more to do than scaling?) or to use some layout-algorithm-based-libraries (e.g. graphviz, tulip, networkx), feed them with the distances between the vertices and hope the layouting-algorithms are keeping the distances while plotting in a good-to-view-at way?
If non-layouting-plotting is the way to do it: which library do you recommend?
If layout-based-plotting is the way to do it: how can i make use of the distances/coordinates in these libraries? And which library do you recommend?
Thanks for all your input!
Sascha
EDIT: I completed a prototype implementation using the PLplot library (http://plplot.sourceforge.net/). The results are nice and should be enough for the moment. I discovered and chosed this library because a related project (VRPH Software Package / Groer) used this plot and the source code was distributed. So the implementation was done in a short amount of time. The API is in my opinion bit awkward and low-level. Maybe there are some more modern (maybe not a c-based library) libraries out there? MathGL? Dislin? Maybe i will try them too.
The nice thing about drawing multiple tours in a vehicle routing problem is that "not so bad" algorithms tend to discover nice non-overlapping and divergent tours which is really good for the eye ;-)
It is not quite clear what you are trying to archive, but if I understand your question correctly, then you could do it using OpenGL. Having vertex coordinates, it should be fairly easy.
You can use Gnuplot with a input text file that contains your solution.
It is convenient to draw the points (vertex) then lines (agents paths) than link them.
To make the plot script easy, you can have a separate file for each vehicle, if the number
of vehicles is known.
check out:
http://www.cleveralgorithms.com/nature-inspired/advanced/visualizing_algorithms.html