
Using the canvas feature
The canvas feature lets you use an image as the background to the planar view. The image may be scaled and positioned so that you may compare your lens design to a published one, for example.
To use the canvas feature:
- Open the options panel of a Planar window
- Select the Canvas tab
- Drag an image file onto the image well
- If desired, enable image calibration and enter the offsets and scale
- To remove the image, press the Clear button> or use the Clear canvas menu item (on the Graphics menu and on the Planar view contextual menu
Below is what the canvas tab looks like

Canvas parameters
The canvas tab contains controls to set the position and size of the image on the planar view. The coordinates are defined as follows:

Offset
Enter the (y,z) coordinates in mm of the reference point. Enter the pixel coordinates (h,v) of this point in the image, measured from the lower left corner.
Scale
Enter a known length for which you know the number of pixels. For example, if the total width of the area represented in the image is 10.3mm and the image is 250 pixels wide, then set the scale length to 10.3 and the parameter n to 250.