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View Full Version : Video Manipulation - Need help w/ research



DiablodeMorte
01-27-2008, 04:28 AM
Hello Everybody,

I had this idea for a project but I'm not entirely sure where to begin. In short, the idea behind the project is to replicate the Wii-Remote's ability to track 4 IR points. I looked at the PixArt site(the company who made the actual chip for Nintendo) but their site is very hard to navigate and I didn't get anywhere. When I brake the project down I get the following "requirements"
-1)Input of CCD camera/NTSC video signal
-2)Algorithm to examine said input
-4)Output of ir point location.

For 1) I figure I'm going to have to some how take a video signal and then break it down into a huge array. Is there a better way? How would I achieve this? I looked at Hitt Consultings HC-OSD Overlay Module since it inputs video like I need and also uses a propeller but I don't really understand the code. I would love some information on how I would achieve the video breakdown

For 2) I'm sure I can find a algorithm on the internet that will solve this problem. Will probably have something to do w/ bringing up the contrast and then looking for the brightest points

For 3) Probably going to use serial and since thats well documented I probably don't need any help on this end.


Thanks in advance for any suggestions/comments,
Diablo

Fred Hawkins
01-27-2008, 07:13 AM
Does the wii bother with a video input at all? It seems easier to just to put an ir-only filter on the ccd.

VIRAND
01-27-2008, 09:59 AM
Right, with IR filter you get only the IR dots and it's really simple to count out their x,y coordinates
and store them when you get to them while reading the CCD.

Another app for this would be to use a laser pointer and CCD->Propeller->Videoprojector
to virtually draw on a wall. Use a red filter then.

DiablodeMorte
01-27-2008, 11:10 AM
Fred Hawkins said...
Does the wii bother with a video input at all? It seems easier to just to put an ir-only filter on the ccd.


Unless I really don't understand CCD cameras.. Don't they still output a video signal? Is it a different video signal than a normal video say from a dvd player? I'm going to assume it is.. and now that i think of it ofcourse it is. How would I use said CCD camera w/ the prop then?

And yes, the wiiremote does use an IR filter.

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Current Projects:
Robot Control Via Skype API - Dev Stage(50% Complete) - Total(25%)
Robot Localization Via Xbee's - Research Stage
IR Tracking with Propeller - Research Stage

Harrison.
01-27-2008, 11:31 AM
CCD (Charged-Coupled Device) is just the name for the type of image sensor. Another common (and extremely inexpensive) imaging sensor is the CMOS imaging sensor. A quick search on google will give you tons of information on these devices.

All cameras (that I am aware of) use an imaging sensor and various chips to convert the digital/analog non-standard camera sensor signal to standard NTSC/PAL/USB/Firewire, etc. It is generally cheaper to just buy a camera module that outputs NTSC/PAL (cheaper probably due to higher demand and higher availability).

Search these forums for 'PropCAM', which is a camera Phil is working on for interfacing with the Propeller. There is also a serial camera module that sparked some interest a few months ago. It isn't nearly as fast as other cameras, but it would help as a proof of concept.

As for your implementation: You would definitely want to use an IR filter that will only allow your chosen IR wavelength to pass. Then all you need to worry about is the actual sensor/interface. It would probably be cheapest to use the Viewport video capture driver that uses a high speed video ADC and a cheap NTSC B/W camera. It captures your video into a large array that you can process with another cog.

Regardless of your choice, you probably won't reach the processing speeds and resolution the wiimote can achieve. I recall that the specs were close to 100fps @ 1024x768 (interpolated) with real time IR blob tracking/sizing. I messed with a wiimote and .NET library during Christmas break and found the tracking to be incredibly fast and accurate.

Post Edited (Harrison.) : 1/27/2008 4:39:49 AM GMT

DiablodeMorte
01-27-2008, 12:16 PM
Thank you Harrison. I'll look into the PropCAM and google like a crazy man..

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Current Projects:
Robot Control Via Skype API - Dev Stage(50% Complete) - Total(25%)
Robot Localization Via Xbee's - Research Stage
IR Tracking with Propeller - Research Stage

SimDan
01-27-2008, 01:10 PM
WiiLi has lots of information on the workings of the Wii Remote here http://www.wiili.org/index.php/Wiimote#IR_Sensor

It looks like that the Wii Remote does not transmit an image dump of the IR sensor as that would be bandwidth prohibitive with the Bluetooth interface it uses. Rather, the Remote takes care of the image processing and transmits the resulting tracking data.