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
> __________________________________________________________
>
> Public Seismic Network Mailing List (PSNLIST)
>
> To leave this list email PSNLIST-REQUEST@.............. with the body 
> of the message (first line only): unsubscribe
> See http://www.seismicnet.com/maillist.html for more information.


  
    
  
  
    

      
      
      
      
      
      
      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
      

      __________________________________________________________
      

      

      Public Seismic Network Mailing List (PSNLIST)
      

      

      To leave this list email PSNLIST-REQUEST@.............. with the
      body of the message (first line only): unsubscribe
      

      See http://www.seismicnet.com/maillist.html for more information.