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Chapter 5
Performing Machine Vision Tasks
© National Instruments Corporation
5-7
Choosing a Method to Build the Coordinate Transform
Figure 5-4 guides you through choosing the best method for building a 
coordinate transform for your application.
Figure 5-4.  Building a Coordinate Transform
Start
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Object positioning
accuracy better
than ±65 degrees.
The object under
inspection has a straight,
distinct edge (main axis).
The object contains
a second distinct edge not
parallel to the main axis in a
separate search area.
The object contains a 
second distinct edge not parallel 
to the main axis in the same 
search area. 
Build a coordinate
transformation based on
edge detection using two
distinct search areas.
Build a 
coordinate transformation
based on edge detection 
using a single search area.
Object positioning
accuracy better
than ±5 degrees.
Build a coordinate
transformation based on
pattern matching
shift invariant strategy.
Build a coordinate
transformation based on
pattern matching
rotation invariant strategy.
End
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