differential the edge detected on each of 2 virtual lines

[wuliao23]

i have a question..
now i draw 2 virtual lines on a image-- virtual line "A" and virtual line "B"
may i know that is that possible to specified the ROI for virtual line "A" and virtual line "B" differently??
because i need to do the edge detection...
then i need to specified is this the edge detected by virtual line "A" or virtual line "B"..
is that possible to do so by drawing 2 virtual lines on a image??

[Jaidev]

Hi wuliao,

This could be easily accomplished in NI-Vision Assistant. You can open an image and then add the Edge Detector step. Every Edge Detector step lets you draw a virtual line on the image and then detects edges on it. Since you can draw only one virtual line per Edge Detector step, you will need to add two such steps for your application. Since you can always distinguish between the outputs of the two steps, you will always know where a certain edge was detected.

Once you have the algorithm ready in Vision Assistant, you can export it to LabVIEW.

Please let me know if you need any more details.

Jaidev

[wuliao23]

i get the ROI descriptor from the property nodes of the image display..
Is that possible to differential the edge detector by virtual line "A" or virtual line "B" by
just create one image display and have two ROI descpritor from the  property nodes of the image display?
will it differential the this is the ROI descriptor for virtual line "A" or virtual line "B"?

or i cannot do by this way ??
but if get the ROI descriptor by vision Assistant, is that i can simply draw the line on the image display to get
the edge detected when imported to Labview every time i run the program?
or the location of the line is needed to  be adjust by the coodinates only?

thanks for helping me!!

[Jaidev]

Hi wuliao,

When you export Vision Asst code, you will have two edge detector steps. If they take only the ROI decriptor as input, try using the IMAQ Select Line.vi. It gives you a prompt (new window) to draw lines on the image and returns an ROI descriptor.

Jaidev

[wuliao23]

thanks you very much...
i will try this method....

[wuliao23]

sorry for disturbing again..
i have try many times to get the ROI descriptor from IMAQ select line.vi and i failed to do it.
i don know how to connect the line(output of IMAQ select line.vi) as the ROI descriptor..
can anyone give help on this??
thanks..

[Jaidev]

Hi wuliao,

You can use the IMAQ Convert Line to ROI.vi for this. You can find this in the Vision and Motion>>Vision Utilities>>Region of Interest>>Region of Interest Conversion palette.

Jaidev

[wuliao23]

yes...
i get it...
thank you very much..

[wuliao23]

hi,
is that possible to create 1 IMAQ edge tool but have 2 ROI descriptor??
thanks..
 

[wuliao23]

another question..
is that the IMAQ edge detection depend heavily on computer performance??
i use the IMAQ edge detection on a video playback, and once edge detected, time will be taken, will it depend heavily on computer performance??
why every time i run the program, it give me the different value on the time reading for the same video and same ROI descriptor??
thanx..