concentric rake

[mat84]

Hi to everybody,I`m a newby with labview and the module vision...

I have to use concentric rake on a frame captured on a video, but it stops with this error:

Error -1074395720 occurred at IMAQ Concentric Rake
  Invalid ROI.

Possible reason(s):

IMAQ Vision:  (Hex 0xBFF605B8) Invalid ROI


I`m not able to find a way to input a correct ROIdescriptor I think.....

thanks for the help

[muks]

Have you tried this?

[mat84]

yes I tried it but it gives me the same error...

[mat84]

could be the problem on the output concentric rake connection?

how can I diplay the edge on the image?

thanks

[gregstoll]

mat84 -

From the error you mentioned it sounds like either Concentric Rake is getting either an invalid or wrong type of ROI.  Can you post your code or a screenshot of your diagram so we can take a look?

Thanks!

Greg Stoll
Vision R&D
National Instruments

[mat84]

this is the block diagram.......I think there are a lot of mistake because is my 7th day with LABview:-)
thanks a lot!
Mattia

[gregstoll]

Mattia -

Can you put a probe on the the output of IMAQ WindGetROI to see what ROI is being passed to IMAQ Concentric Rake?

My guess is that there's no ROI on the image window and that's why IMAQ Concentric Rake is returning an error.  You may have to loop and wait until there's actually an ROI on the window before calling IMAQ Concentric Rake.  Another alternative would be to call IMAQ Construct ROI (to let the user select an ROI and click "OK") to get the ROI.

I'm more used to writing code using the Image Display Control instead of the Wind* functions, so hopefully one of these suggestions will work 🙂

Greg Stoll
Vision R&D
National Instruments

[mat84]

Greg-
thanks to reply. I tried to modify the block diagram but I have always the same error

and looking the probe it seems that the rectangle is correct

[gregstoll]

Mattia -

Whoops - my mistake!  IMAQ Concentric Rake only works on ROIs that are an annulus.  If you want to do a Rake-type operation on a rectangle use IMAQ Rake instead.

Greg Stoll
Vision R&D
National Instruments