I have a program that's creating data points, some of them are in the shape of a log function and some are lines. I need to be able to fit curves to these data points to be able to extrapolate. Are there any C++ libraries that can do this for me?
Try the GNU scientific Library: http://www.gnu.org/software/gsl/manual/html_node/Linear-regression.html
CERN's ROOT package is probably your best option. It combines plotting, GUI resources, and stable computing resources together in one great package.
Related
For a scientific project i need to compress video data. The video however doesn't contain natural video and the quality characteristics of the compression will be different than for natural footage (preservation of hard edges for example is more important than smooth gradients or color correctness).
I'm looking for a library that can be easily integrated in an existing c++ project and that let's me experiment with different video compression algorithms.
Any suggestions?
Look at FFmpeg. It is the the most mature open source tool for video compression and decompression. It comes with a command line tool, and with libraries for codecs and muxers/demuxers that can be statically or dynamically linked.
As satuon already answered, FFmpeg is the go-to solution for all things multimedia. However, I just wanted to suggest an easier path for you than trying to hook your program up to its libraries. It would probably be far easier for you to generate a sequence of raw RGB images within your program, dump each out to disc (perhaps using a ridiculously simple format like PPM), and then use FFmpeg from the command like to compress them into a proper movie.
This workflow might cut down on your prototyping and development time.
As for the specific video codec you will want to use, you have a plethora of options available to you. One of the most important considerations will be: Who needs to be able to play your video and what software will they have available?
all I want is to create circles (from data) on a grid for specific sets of data with different colours. These might be objects I have created to be placed on grid or from the program itself. I was using POVRAY but it is massively complicated and I don't have the time. Unless anyone has a tutorial on how to read data from files and extract all the numbers and used successfully in .pov files.
There are several programs/environments (not C++) that can do this directly. One is gnuplot; another, more robust tool is R. Although with R there is a bit more of a learning curve to really get moving.
Have you considered GNUplot?
It has a simple syntax, so you can just convert your data file into an input file for gnuplot.
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
I am working on the system that compares images. MPEG-7 standard provides some descriptors which can be used for that e.g: Dominant Color, Color Layout, Edge Histogramm, Color Coherence Vectors.
Do you know where i can get a source code for some of these methods?
Thx!
You can also use the Windows and Linux executables, or easy-to-use API based on OpenCV library, developed for BilVideo-7 video indexing and retrieval system: http://www.cs.bilkent.edu.tr/~bilmdg/bilvideo-7/Software.html.
The ISO distributes reference software as part of the MPEG-7 standard, and among other things it includes feature extraction code for the visual descriptors. The zip file contains another zip file called XMWin.zip, which contains the source. (Despite the "Win" name, it contains instructions for compiling on both windows and unix.)
Hope this helps to other programmers:
Here you can find one implementation on C#
Here another implementation in Java.
For Future readers, there's a CPP library that claims to be easy to use here.
https://github.com/mubastan/mpeg7fex
This has been tested on OpenCV 3, so this is at par the latest.
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.