By Brian Robertson on Fri, Aug
19, 2011
One of the most unique and powerful features of IMPACT software is the
ability to work with lists of data. When performing image analysis,
inspection locations can sometimes be numerous and data sets can be
lengthy. In this case, the IMPACT list handling tools can be very useful
and efficient.
The primary list handling tools are the List Sorter, List Loop, Data
Instance and Data Set tools.
List Sorter
The List Sorter, as the name implies, sorts the incoming data by the
selected Sort Feature. Incoming data can be a Blob, Point, Integer, or
Real list. The corresponding Sort Features are Blob Features (area,
height, width, etc), X or Y point value, Integer value, or Real Value.
The output of this tool is a Sorted List.
List Loop
The List Loop tool can “step through” a list while doing an operation at
each step. For example, you might want to step through a Centroid List,
and, at each centroid point, execute another vision tool to inspect a
feature. The List Loop tool makes this implementation much simpler, since
you can use one tool and move it to many locations to do the same inspection,
rather than adding many duplicate tools.
Data Instance and Data Set
The Data Instance tool is used to store values in a list, which can then be
added using the Data Set tool.
The example below demonstrates all of these list handling tools. The
goal of the inspection is to determine the internal radius for each pair of
tabs in each hole.
Determine the Radius
To determine the radius of a pair of tabs, a Circle Gauge tool is
used. But, rather than adding forty circle gauge tools, we will use one
tool, which will be moved to each of the holes, executed, and the radius value
will be stored.
The complete tool set is described below (the number in the graphic below
corresponds to the detail in the bulleted list that follows.)
- Blob tool - finds the centroid
of each of the forty holes and creates a centroid (point) list.
These centroids will be used to position a Circle Gauge tool at each hole.
- List Sort - puts the
centroids in Y-order direction.
- Data Set tool - clears the
previous result (from tool 8), the list of Radii.
- List Loop
tool - steps through the centroid list. The tools inside the loop
execute for every element in the list.
- Data Instance - uses the
current centroid list element (as the List Loop tool steps through them)
to create an Origin (x, y, and angle).
- Circle Gauge - finds the
internal radius of the tabs in each hole.
- Data Set tool - adds the
current radius value to the final list of radii.
- Data Instance - stores the
list of radii for all the holes.
The final result is the list of 40 radius values as shown in the Data
Instance tool property tab below.
Summary
In summary, IMPACT software is very efficient at working with list data from
vision algorithms. The List Sorter, List Loop, Data Instance, and Data
Set tools can easily manipulate and step through list data to facilitate
repeated operations.
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