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Messages - Alrecenk

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Wiimote Interactive Whiteboard / Re: Drawing lines not smooth
« on: January 25, 2008, 09:20:08 AM »
There are only a few reasons I can think of that it wouldn't be smooth:
The LED is not bright enough, the wiimote is positioned badly, or the wiimote simply doesn't track accurately enough for the amount of accuracy you want. It sounds like you've tried a lot of this already, but you might try checking the battery voltage/resistance(rechargeable AAAs have less voltage than regular AAAs), bundling a couple of LEDs together, and positioning the wiimote as close to the screen as it can get and still see all the corners and as aligned with the screen as possible(also make sure that it's not at an angle where your hand might occasionally block it). I had a lot of trouble getting my homemade pen to track well with an LED I bought at radio shack, but the key chain light I bought off line which is much brighter tracks very smoothly. Perhaps you could get the same effect by bundling several LEDS together.


Comments and Feedback / 500 error
« on: January 16, 2008, 06:35:14 AM »
I saw where you mentioned this in the shoutbox, but I didn't see a thread for it so I'll go ahead and post it. I just got the 500 error attempting to go to this link:
and shortly after that I got it refreshing the main page.

Comments and Feedback / Page Link Broken
« on: January 13, 2008, 02:20:01 PM »
In the "say hi" forum clicking the two to go to the second page of posts takes you back to the first page. That's the only board with 2 pages at the moment, so I can't say if it would do it in other sections.

Wiimote Interactive Whiteboard / Re: Source Code Doesn't Compile
« on: January 13, 2008, 09:30:57 AM »
That takes care of the cross thread issue, but now I get another PInvoke stack imbalance in it's place on the mouse button up call, and though I can compile and run the program and move the mouse without it crashing I am, not surprisingly, unable to click anything.

edit: Changed title of the thread. The errors are and have been runtime errors.    My apologies if I misled anyone.

Wiimote Interactive Whiteboard / Re: Source Code Doesn't Compile
« on: January 12, 2008, 07:12:44 PM »
I updated the source, and it seems that if I run the built exe it works like I would expect. I didn't do anything to fix that other error, and I wouldn't really know where to start as my c# experience is limited. It still throws when I run in debug mode, but at least now I can get something done....well, maybe not right now...*plays video games*

Wiimote Desktop VR/Head Tracking / Re: Improving to 6 DOF head tracking
« on: January 11, 2008, 10:42:48 AM »
I attempted to work out the mathematics for more 3D tracking, but I ultimately arrived at a system of 3 quadratics that I was unable to solve. The basic idea was to have a set of calibration points with position given in actual space, and in camera space. With 3 calibration points it should be possible to determine all of their distances from the camera, and given the fov etc of the camera find their positions in world space relative to the camera. This calibration should work as long as those 3 points remain in their original configuration, but it's not enough information to track individual points in 3D. For that you need more than one camera, and to calibrate a camera's position and orientation completely it takes 4 calibration points I believe. I was originally thinking about this in relation to a general application that could track a point in 3D using 2 or more wiimotes, and I hadn't really thought about using it for advanced head tracking until I read this post. Given that you can assume that there are always 3 points in a set configuration the math should be considerably simplified. At the moment my compiler and I don't seem to be getting a long, but I'd be happy to provide mathematical assistance if someone wants to attempt this.

Say Hi! / Yo
« on: January 10, 2008, 12:18:28 AM »
Hi, I'm a compsci-math major who loves nothing more then putting fancy formulas behind new toys.  I don't have a whole lot to say at the moment, but I should have more as soon as I've found out which of my ideas are ridiculous and which ones might actually work.

IR Pens / Re: Where can I get IR pen components in Tucson?
« on: January 10, 2008, 12:09:02 AM »
I've got one. It works pretty well. I posted on my first few hours of experience with it on the first info page before seeing this post:

I should read more before posting, but all this IR camera talk makes me giddy. lol

Wiimote Interactive Whiteboard / Source Code Doesn't Run in Debug Mode
« on: January 10, 2008, 12:04:20 AM »
I downloaded the C# source code from this board, and when I attempt to run the program in debug mode I get this error:

A call to PInvoke function 'WiimoteWhiteboard!WiimoteWhiteboard.Form1::mouse_event' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

on this line:

mouse_event(MOUSEEVENTF_LEFTDOWN, 0, 0, 0, 0);

the first time I attempt to click with the ir pen when calibrating.

and if I uncheck the cursor option, and try it I get:

cross-thread operation not valid: Control 'CalibrationForm' accessed from a thread other than the thread it was created on.

on this line:


immediately after the last calibration point. I'm using visual c# 2005 express edition on a windows xp home machine. I can run the precompiled application, and my wiimote connects fine etc. Is there a certain configuration I need to be compiling in to get this to work or any additional files I need? I haven't put very much time into researching this problem, so it may be trivial to fix, but I figured it was worth posting anyways for anyone who might be as surprised as I was when the original source did not compile. Any help would be appreciated.

This website seems to sell IR keychain lights that might be ready to use, but I haven't tested them.

After some difficulty constructing my light pen I ordered the cheapest infrared keychain light made by that site for about 20 bucks after shipping. It works quite well, but it is smaller and might not be as comfortable to hold for long periods of time as a homemade pen. The light is fairly directed, and it didn't work very well facing forward, but I calibrated it holding the light facing toward me, and it works like a charm. It is quite smooth (on my 17 inch monitor), and I was able to calibrate it as a pointer across the room from my wiimote without having any problems with the light dissappearing(like my homemade pen did). That's my two cents for anyone too lazy(or unsuccessful) to create an infrared pen, and too impatient to wait for them to be sold: it works, it's bright, but the small keychain form factor and high price may be undesireable for practical use.

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