How to control a button using motion in opencv? - c++

I want to control a button using hand motions. For example, in a video frame I create a circle-shaped button. Then when I move my hand to that circle I want to play an mp3 file, and when I move my hand to another circle the mp3 song stops playing. How can I do this?
i am working in windows7 OS and i use microsoft visual studio 2008 for work...

You have infinite options to do that. Probably the easiest is trying to do background segmentation and then check if there's anything which is not background that overlaps with the button area. It would work with any part of your body, not only your hands, but that might not be an issue.
Another option would be to try to detect and track your hands based on skin color. For this you need to obtain an histogram of the skin color and then use it with the camshift tracker. A nice way to obtain the skin color on runtime would be running a face detector (haarcascade) and getting the color from the detected region.
I'm sure there are hundreds of additional ways to do it.
Also, if you can get your hands on a Kinect camera it could help a lot. Check OpenNI and the MS Kinect SDK to see what it enables you to do.

The first thing you will have to do is create a haar cascade xml file and train it on human hands.

Related

full screen and zoom in Koolplot

I'm trying to graph some things in C++ and Koolplot seems like a very simple and suitable library to do so with. I'm stuck, however, on finding some documentation about it that allows me to fullscreen the application (or resize it like you can do so on lots of applications, chrome, word, discord...). As well as this, I can't find or see how i can allow the user to drag the graph around with the mouse as well as zooming into a point of a scatterplot or function. If anyone has any ideas about these things i'd appreciate it, thanks.
The short reply is: cannot do.
Koolplot uses for drawings of the charts a modernized version of the venerable BGI driver. It was invented once upon a time, when personal computers were still running on some DOS version. Those times the graphics were full screen, hence of fixed size. This particularity was kept in the modernized WinBGIm library.
Zooming or panning properly a chart present on the screen require access from the drawing/painting routines of Koolplot to the data to be shown. This is not the case. If you look once again in the source code, you will note that in the implementation efforts were made to keep separated data to be plot from the actual drawing on the screen.
In conclusion, to do what you want, you will have to modify WinBGIm such that it manages correctly a drawing surface of variable dimensions and modify koolplot such that data to be shown is owned by (or aggregated with) Plotstream class.

Is it possible to get the physical shape of a touch contact (a bitmap) in Windows?

I want to be able to determine the size AND rotation of touch contacts for a finger painting app. Right now laying down a long finger diagonally gives me a giant square, which is not what I want at all, I want a long rectangle at an angle.
I figured this would be provided by the system, but even the Surface Pro 4 hardware doesn't have this. But I could extract the info if I had a bitmap of the contact area.
So far googling WM_INPUT related things hasn't helped. Is this even possible?
Edit: a way to get POINTER_TOUCH_INFO::orientation is what I'm looking for, to be precise. My touch screen doesn't put any value into this field.
Edit 2: There's some useful research on this (http://hci.cs.umanitoba.ca/assets/publication_files/2009-UIST-wang-DirectTouchSurface.pdf), all I need now is access to the contact shape.
Edit 3: I got an answer from #msdev, they also suggest motion tracking. The only thing lacking now is continuous tracking, and I guess there's no way to reliably solve that without a contact bitmap. Maybe teaching a neural net could work.
Since Windows 8 there are new messages:
- WM_POINTERUP
- WM_POINTERDOWN
- WM_POINTERUPDATE

How to remove a specific background from a video (OpenCV 3)

I am relatively new to OpenCV. My program will have a fixed camera that will track insects moving passed it. I figured that this would mean that I could remove the background from the video. I have attempted to use the method (which I found in a tutorial - http://docs.opencv.org/3.1.0/d1/dc5/tutorial_background_subtraction.html#gsc.tab=0):
pMOG2 = cv::createBackgroundSubtractorMOG2();
..
pMOG2->apply(frame, background);
However, how does this determine the background?
I have tried another way, which I thought might work, which was to capture the background when the program first starts and then use absDiff() or subtraction() on the background and current frame. Unfortunately, this results in a strange image which has parts of the static background image displayed over the video, this messes up the tracking.
I am a bit confused as to what would be the best way to do things. Is it possible to remove a specific background from each frame?
Thanks!

OpenGL - Display video a stream of the desktop on Windows

So I am trying to figure out how get a video feed (or screenshot feed if I must) of the Desktop using OpenGL in Windows and display that in a 3D environment. I plan to integrate this with ARToolkit to make essentially a virtual screen. The only issue is that I have tried manually getting the pixels in OpenGl, but I have been unable to properly display them in a 3D environment?
I apologize in advance that I do not have minimum runnable code, but due to all the dependencies and whatnot trying to get an ARToolkit code running would be far from minimal. How would I capture the desktop on Windows and display it in ARToolkit?
BONUS: If you can grab each desktop from the 'virtual' desktops in Windows 10, that would be an excellent bonus!
Alternative: If you know another AR library that renders differently, or allows me to achieve the same effect, I would be grateful.
There are 2 different problems here:
a) Make an augmentation that plays video
b) Stream the desktop to somewhere else
For playing video on an augmentation you basically need to have a texture that gets updated on each frame. I recall that ARToolkit for Unity has an example that plays video.However.
Streaming the desktop to the other device is a problem of its own. There are tools that do screen recording, but you probably don't want that.
It sounds to me that what you want to do it to make a VLC viewer and put that into an augmentation. If I am correct, I suggest you to start by looking at existing open source VLC viewers.

OpenGL Window Overlay

What I need to do is create a program that overlays the whole screen and every 30 seconds the screen needs to flash black once.
the program just needs to be on top of everything, doesn't have to work over the top of games, but wouldn't say no if it did!
But i've got no idea where to start. Ideally the solution would be cross-platform for both windows and osx.
Does anybody have any ideas about where I should start or could whip up a quick demo?
OpenGL (you tagged it as such) will not help you with this.
Create a program, that overlays the whole screen,
The canonical way to do this is by creating a decorationless, borderless top level window with some stay-on-top property being set.
and every 30 seconds the screen needs to flash black once.
How do you define "flash back once"? You mean you want the display become visible for one single vertical retrace period or a given amount of time? Being the electronics tinkerer I am, honestly, I'd do this using a handfull of transistors, resistors and capacitors, blanking the analog VGA signal.
Anyway, if you want to do this using software, this is going to be hard work. If you'd do this using the aforementioned stay-on-top window, when you "flash" it away, all the programs with visible output would receive redraw events, which to process would take some time. In the best case scenario the system uses a compositing window manager which can practically immediately show the desktop. Without a compositor its going to be impossible to "flash" the screen.
Ideally the solution would be cross-platform for both windows and osx
A task like this can not be solved cross plattform. There's too much OS dependent work to do for this.
I presume this is for some kind of nerological or psychological experiment. I think doing this using some VGA intercepting circurity would be actually the easier, quicker to implement solution. I can help you with that. But I think there's another StackExchange better suited for this. Unfortunately digital display interfaces (DVI, HDMI and Display Port) use a complex line code scheme, which can not be blanked as easily as VGA, so you must have a computer capable of analog (=VGA) output and a display with a VGA input.