Spatial Scale Calibration

Lets you calibrate an image, region of interest, or multi-ROI so that you can measure true dimensions. For spatial scale calibrations, the known length of a ruler is used to update image spacing and obtain the correct values. To perform a spatial scale calibration, the dataset must include a fiducial marker or other feature of known length.

1. Open the uncalibrated image, region of interest, mesh, or multi-ROI.
2. Zoom-in on the fiducial marker or object of known dimensions, recommended.

   Note You can remove image interpolation to better view the edges of the marker or object. To do so, choose Interpolation > Nearest in the 2D settings box on the Data Properties and Settings panel.

3. Select the Ruler tool and then draw a line that is exactly the same length as the fiducial marker or feature of known length, as shown below (see Using the Ruler Tool).

   

4. Right-click the object you need to calibrate in the Data Properties and Settings panel and then choose Calibrate Spatial Scale in the pop-up menu.

   The Calibrate Spatial Scale dialog appears.

5. Do the following in the Calibrate Spatial Scale dialog:
   • Choose the required ruler in the Select the ruler to calibrate with drop-down menu.
   • Enter the 'real' length of the ruler in the Expected length edit box.
   • Check the Reduce distance from origin option, recommended.

     

     Note If the 'Reduce distance from origin' option is selected, the calibrated dataset's position in space, also known as the point of origin, will be closer to 0,0 than if the distance from origin is not reduced. Refer to Advanced Dataset Properties for more information about position in space and other parameters.

   • Click OK.

   Spacing is updated automatically. You can view the updated dimensions of the calibrated object on the Data Properties and Settings panel.