I like the idea of using a WEBcam or something to look at the red dot
then use a custom program to read the video and turn the graphic data
into rectangular coordinates of a standard four quadrant graph
with the point resting in the center of the graph
But to do this in near real time may not be possible for myself to do.
The max rate will be like 30Hz to 60Hz which is a video frame rate.
Video is usually encoded and needs to be uncompressed.
Uncompressing video takes lots of time to do so like a
series of BMP captures at whatever rate would be the thing to do.
You would take screenies at like 30 per second in a modulo fashion
then save all after an alarm and the series of like
108000 BMP images would be decoded into a series of (X,Y) coordinates ??
The concept as seen From a layman's point of view.
A mass on end of a bent over spring wire might do for a vertical sensor ?
Regards,
geoff
On 3/8/2013 3:05 PM, Charles R Patton wrote:
> I would use a shorter projection distance so the dot is on a smaller
> surface -- perhaps 10" square. Or even smaller -- you'll get the
> idea in a moment. I'd make this surface a back projection screen such
> as in the old microfilm readers. Frosty Mylar sheet or some similar.
> Mainly rear projection so I wouldn't have to get into correcting for
> angular skew, but that would be your choice if you want to do slightly
> more image processing. Next I'd take a standard USB webcam and view
> the image of the dot projected on the film. Run this through any one
> of several free image processing libraries (depends a bit whether
> you're using Windows or Linux) or write a simple custom program to
> extract the pixel position of the dot. Typical low resolution
> webcams give the position to 640x480. Actually if you use image
> processing, this can be interpolated due to the 8 bit quantization of
> the dot in the image and that it will typically spread over several
> pixels. Your frame update rate will be around 30 times a second. The
> size of the image is not the resolution limit, the webcam is. So you
> can also get higher resolution webcams. In any case, the projected
> image size is not very critical unless you make it too small. The
> point here being that it can easily be made to be a table top size.
> Regards,
> Charles R. Patton
>
>
> On 3/8/2013 5:47 AM, Geoff wrote:
>> Scholars and Gentle-peoples,
>>
>> Here is a Video created by myself which shows
>> what i want to measure
>>
>> http://youtu.be/w-6r9o7Mds8
>>
>> Can someone tell me how they might
>> actually, or Do now, measure in real time,
>> the (x,y) coordinate of this moving Laser spot ?
>>
>> Youtube says my video is blocked in some countries,
>> Don't know why, or where it is blocked.
>> Most likely because I used FM general radio broadcast
>> for the Audio part of the video.
>> This station damages the audio before it is transmitted
>> so i do not understand why it makes any difference anywhere.
>>
>> Any Comments ?
>>
>> Regards,
>> geoff
>> __________________________________________________________
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>
--
*************
It is by the Entropy, That I set my mind in Motion.
Entropy is the seeking of equilibrium.
It is by the Entropy that, I set my mind in motion.
I like the idea of using a WEBcam or
something to look at the red dot
then use a custom program to read the video and turn the graphic
data
into rectangular coordinates of a standard four quadrant graph
with the point resting in the center of the graph
But to do this in near real time may not be possible for myself to
do.
The max rate will be like 30Hz to 60Hz which is a video frame
rate.
Video is usually encoded and needs to be uncompressed.
Uncompressing video takes lots of time to do so like a
series of BMP captures at whatever rate would be the thing to do.
You would take screenies at like 30 per second in a modulo fashion
then save all after an alarm and the series of like
108000 BMP images would be decoded into a series of (X,Y)
coordinates ??
The concept as seen From a layman's point of view.
A mass on end of a bent over spring wire might do for a vertical
sensor ?
Regards,
geoff
On 3/8/2013 3:05 PM, Charles R Patton wrote:
I would use a shorter projection distance so the dot is on a
smaller surface -- perhaps 10" square. Or even smaller --
you'll get the idea in a moment. I'd make this surface a back
projection screen such as in the old microfilm readers. Frosty
Mylar sheet or some similar. Mainly rear projection so I
wouldn't have to get into correcting for angular skew, but that
would be your choice if you want to do slightly more image
processing. Next I'd take a standard USB webcam and view the
image of the dot projected on the film. Run this through any
one of several free image processing libraries (depends a bit
whether you're using Windows or Linux) or write a simple custom
program to extract the pixel position of the dot. Typical low
resolution webcams give the position to 640x480. Actually if
you use image processing, this can be interpolated due to the 8
bit quantization of the dot in the image and that it will
typically spread over several pixels. Your frame update rate
will be around 30 times a second. The size of the image is not
the resolution limit, the webcam is. So you can also get higher
resolution webcams. In any case, the projected image size is
not very critical unless you make it too small. The point here
being that it can easily be made to be a table top size.
Regards,
Charles R. Patton
On 3/8/2013 5:47 AM, Geoff wrote:
Scholars and Gentle-peoples,
Here is a Video created by myself which shows
what i want to measure
Can someone tell me how they might
actually, or Do now, measure in real time,
the (x,y) coordinate of this moving Laser spot ?
Youtube says my video is blocked in some countries,
Don't know why, or where it is blocked.
Most likely because I used FM general radio broadcast
for the Audio part of the video.
This station damages the audio before it is transmitted
so i do not understand why it makes any difference anywhere.
--
*************
It is by the Entropy, That I set my mind in Motion.
Entropy is the seeking of equilibrium.
It is by the Entropy that, I set my mind in motion.