Modifying vision calibration to new coordinate system

[nzamora]

I have an image that I have applied a multi-point coordinate system to, easy enough. Next, the point that I call (0,0) within this calibrated image is not where I want to base my measurements off of - I need to find that position somewhere else in the image, but I want the scaling to stay as is. If I apply a coordinate system to a new point, in Vision assistant, it is only used to modify the location of any ROIs used afterwards, and not used to modify measurements taken. Is there a way I can modify the measurements taken using the coordinate system? It is not feasible for this situation to be able to build the calibration off of the true (0,0), it must be built then adjusted.

I also cannot simply add/subtract the difference between my adjusted (0,0) and the calibrated one because the image calibration is non linear, thus the use of multi-point calibration.

[Bob_Schor]

 There is an Image Calibration function in the Image Assistant that you can use with a known "Grid" image to create a Calibration that you can subsequently use with Image Correction to correct distortions and redefine your Image Origin (0, 0).  I've never used them, and the description I once saw of the procedure seemed complicated.

So the answer seems to be that the Tools may be present, but I, personally, don't know how to use them.  You might try experimenting and/or looking for Help files on specific tools ...

Bob Schor

[samazing]

Hi Nzamora,

How are you taking your measurements? Are you simply doing something like a particle analysis or feature location and using the coordinates to take a measurement? Typically I've see metrology done by using two or more features (edges, pattern matching, etc.) and then using the caliper to take the measurement.

In a quick test I ran, I was unable to move the origin (0,0) away from the top left corner, would it be possible for you to include your source code so that we may replicate the behavior you are seeing? This would include a VI with the vision assistant code, the image, and also the calibration file.

Best,

Sam K

[ChristopheC]

Sorry for the late answer. Yes, you can do that from Vision Assistant.

What you want to do is first insert the steps that will locate the new calibration axis center and angle, then insert the calibration step. Calibrate your system using any of the calibration type. The important part is then to enable the checkbox "Learn Calibration at Each Iteration". The name might be a bit misleading as the full calibration will not  be relearned (unless you chose simple calibration), but the calibration axis will be updated.

When the check box is enabled, you can click on the Origin item in the calibration data, and point to the new origin. Same for the Angle or X-Axis point, depending how you defined the calibration axis.

Each step you insert after will use that new calibration axis when computing real-world measurements.

Hope that makes sense.

Christophe