Rockwell Automation 5370-CVIM2 Module - Manual (Page 328)

Chapter 7
Inspection Tools
7–90
Perspective
A perspective “shape” image tool consists of two separate windows: a
perspective AOI, and a rectangular “destination.” It provides a means of
reshaping the contents of the original image in cases where the original
image is slightly distorted because the camera is not perpendicular to the
image.
NOTE: The perspective image tool gives slightly better results than the
quad image tool when used to correct for perspective distortion, but it runs
more slowly.
The image appearing in the perspective AOI is transformed, according to the
shape of both the AOI and the aspect ratio of the destination. Each point in
the AOI is “mapped” into a corresponding point in the destination. The
perspective image tool can be used to perform the same kinds of
transformations as the quad image tool, with the added capability of
correcting for perspective distortion.
Figure 7.73 illustrates this concept by using the image of a square grid where
the image plane is not perpendicular to the camera. The resulting grid is thus
a trapezoid, and the AOI is positioned around the grid.
Figure 7.73 Example: Image Tool With Perspective “Shape”
AOI
Destination
The squared destination shows the resulting “perspective” image.
The effect of the perspective image tool, in this example, is to stretch the
upper part of the original image horizontally and vertically, but not the