Elasticity

Specify the upper limit of elasticity with relation to the model pattern for a pattern to be found. The allowable elasticity must be specified in pixels. The default value is 1.5 pixels.

This default value rarely needs to be changed. It is not recommended to set a large value for the allowable elasticity, except in the case of a "bag-like workpiece whose geometry is subject to change".

What differs between when a small value is set for the allowable elasticity and when a large value is set is explained below, using a rather extreme example.

(i) Model pattern
(ii) Allowable range ±1.5 pixels
(iii) Allowable range ±4.0 pixels
Allowable elasticity range

Suppose that you have taught a circle, like the one shown in Fig.(i), as the model pattern, and you have a pentagon in the image, as shown in Fig.(ii). When a small value is set for the allowable elasticity, the pattern in Fig.(ii) is not found because its geometry is judged different. When a large value is set for the allowable elasticity, however, even the pattern in Fig.(iii) is considered to have the same geometry and is found.

When a large value is set for the allowable elasticity, the GPM Locator Tool needs to take many distortedgeometries into consideration and takes longer to find a pattern. Conversely, setting a small value leads to a shorter location time.

When a large value is set for the allowable elasticity, it appears that patterns can be found with high scores. However, this setting is often prone to incorrect location or failure to find a matching pattern. This can also be inferred from the example in Fig.(iii).

Keep in mind that setting a large value for the allowable elasticity can generally result in frequent incorrect locations.