How to keep the first edge coordinate as reference?

[amila]

Hi..

My program is to detect movement of an object using a webcam and Labview 8.5.1.

I used an IMAQ RAKE with 'top to bottom' scan direction to find the first edge of my object and I want to keep the coordinate of this first edge (X1,Y1). Then when the object moves, the IMAQ RAKE will find the first edge with same scan direction and the coordinates (Xi,Yi) are needed to calculate the distance of the movement (X1-Xi,Y1-Yi). And this calculation is running in real-time.

My problem is, when the IMAQ RAKE detect the very first edge (X1,Y1), how can I store this as a reference coordinate that I'm going to use in the calculation? Because in my current program, the coordinate will follow the current first edge detection, thus the distance will always be 0.

Many thanks.

[Antoine Chalons]

QUOTE (amila @ Feb 26 2009, 12:52 AM)

Hi..

My program is to detect movement of an object using a webcam and Labview 8.5.1.

I used an IMAQ RAKE with 'top to bottom' scan direction to find the first edge of my object and I want to keep the coordinate of this first edge (X1,Y1). Then when the object moves, the IMAQ RAKE will find the first edge with same scan direction and the coordinates (Xi,Yi) are needed to calculate the distance of the movement (X1-Xi,Y1-Yi). And this calculation is running in real-time.

My problem is, when the IMAQ RAKE detect the very first edge (X1,Y1), how can I store this as a reference coordinate that I'm going to use in the calculation? Because in my current program, the coordinate will follow the current first edge detection, thus the distance will always be 0.

Many thanks.

place the IMAQ Rake in a loop and use a shift register :

http://lavag.org/old_files/monthly_02_2009/post-7452-1235668135.png' target="_blank">

hope this helps

[amila]

QUOTE (Antoine Châlons @ Feb 26 2009, 05:09 PM)

place the IMAQ Rake in a loop and use a shift register :

http://lavag.org/old_files/monthly_02_2009/post-7452-1235668135.png' target="_blank">

hope this helps

Thanks Antoine.. Sorry for the late reply because I've to solve some errors before I can start using this shift register. This question may sound silly -> where do you get the cluster on the left of the image (containing location pixel, location real-world, etc)? Do I need to build it or it comes from specific VI?

Please refer to my image. I want to calculate the distance using the shift register. Can I just put a MathScript and wire the shift register from both sides?

Many thanks.

Amila

[Neville D]

I think you will help yourself greatly by going through some example programs and a few chapters of an introductory text on LabVIEW; maybe a little tutorial on LabVIEW before you wade into trying to detect motion in an image.

Try looking up clusters, shift registers, and maybe a few image examples after you feel comfortable with LabVIEW.

We are all here to help, and I am not trying to discourage you, but your questions seem to indicate a lack of very basic labview knowledge.

Neville.

PS A mathscript node is the last thing you want to use in an image application. It is extremely slow and its main benefit is being able to run matlab scripts in a LabVIEW environment.