Match page (MExtract)
The Match page of the Source Extraction configures source list matching for the Extract Sources command. When extracting from an image set, source list matching removes sources that pass all the filtering criteria but are not located at the same coordinate in every image of the image set. In other words, this phase produces a final source list that includes only those objects that match in every image. Only the coordinate is used as a matching criterion and source differences such as luminance or shape are not involved. The Tolerance and Matching Region parameters control the area searched to establish a coordinate match at each object location. Depending upon the application, you may or may not need to register the images before using source matching.
When an image set is processed, these preferences determine how the lists of detected objects are matched.
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Matching Region |
Specifies the shape of the region used to determine whether objects in each pair of images refers to the same object. The tolerance determines the size of the region. |
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Tolerance |
The size of the region examined for object matching. |
This operation is the complement of the differencng operation, meaning that objects not matched are differenced. However, this method gives a slightly different result than the simple "set complement" because Matching requires an object to be located in every image whereas Differencing identifies sources that are not matched in a subset of the entire image set.