How the coordinate values change on rotation?

[siju]

I need to know how the coordinates of the pixels change when they are rotated by a certain angle.

Or suggest some VI which will give the new coordinate values after rotation..

pls reply

[Andrey_Dmitriev]

Hi,

You can use 2D Cartesian Coordinate Rotation.vi (from Mathematics->Geometry palette)

Andrey.

[siju]

i tried it .. but it also gave negative values ..

how to convert them in to meaningful values..?

pls reply

[Andrey_Dmitriev]

Combine it with 2D Cartesian Coordinate Shift.vi. You should clear understand where is your rotation center, of course.

Andrey.

[siju]

i tried it .. but it also gave negative values ..

how to convert them in to meaningful values..?

pls reply

[Andrey_Dmitriev]

Hmmm....

Not fully understand where is your problem? Show your code, please.

Quick and dirty test:

Andrey.

Message Edited by Andrey Dmitriev on 06-10-2009 01:51 PM

[siju]

but still the values are negative...

i want to rotate the overlay for the selected roi..

AM UPLOADING THE VI

[Andrey_Dmitriev]

If you will do this exercise accurately, then you will get desired result.

Your problem with coordinate shift (if you not maintain size of the rotated image, then it should be used in calculation. Also be accurate with rotated rectangle).

Otherwise if you need just rotate ROI for overlay, then you can use IMAQ Transform ROI instead of calculation each point separately. See attached example.

Andrey.

[siju]

iam wrkin in LV 8.2

pls send me a screenshot of the VI.

How do i find the reference?

[Andrey_Dmitriev · Accepted solution]

Saved in LV 8.2. Screenshot attached.

Andrey.