Annulus controls to create visible circle

[jeisenstein]

I am trying to use the annulus control on the front panel to specify a circle of a particuly pixel radius, and I'd like to be able to drag the circle around to different X/Y positions.  I have been able to do that, but the problem is, I can't see where the annulus is located on my image (the annulus controls do not output the corresponding circle anywhere)--there's no visual feedback, only text output in the control boxes.  Alternatively, I have been able to create a circle overtop of my image that acts as a region of interest using the ROI property on the property node.  The problem here is that I cannot specify the pixel radius of the circle I draw overtop of my image.

So basically I want to have a circle appear overtop of my image indicating the ROI and I want to be able to control the radius through a controls box. 

Jessica

[Vivek_N · Accepted solution]

Hello Jessica,

You can use the IMAQ Convert Annulus to ROI VI and the IMAQ Overlay ROI VI to accomplish this. The IMAQ Convert Annulus VI takes a control input through which you can specify the radius, X,Y and angles of the annulus. After that, the IMAQ Overlay ROI VI will allow you to see the annulus displayed in the Image Display control. I hope this helps.

[jeisenstein]

Perfect!  Thanks!

[ChuckS]

The problem with that routine is it is an integer. The circle and radius is usually subpixel !

[ahillinaustin]

Hi ChuckS,

Thanks for posting on the forums! If you're just trying to add info to this post, we appreciate it! If you're looking for help with this function, I'd recommend starting a new thread that will be more recent and therefore more likely to have visiblity for the rest of our community. If you're looking for a place to suggest a change to this function, you can head over to the Idea Exchange (http://forums.ni.com/t5/Vision-Idea-Exchange/idb-p/visionideas) and post there.

Best!