rank.ac

Necessity:optional
Value:true | false
Default:false

Parameter for enabling the Auto Context feature. This feature does only work in conjunction searching by images (rank.by=id). Auto Context determines the semantic context of the visual search based on the associated keywords of the image.

A Solr query consists of one or several clauses. Auto Context produces clauses out of keywords associated to the image (specified by rank.by=id) and automatically extends the query with them.

Note: In order to use Auto Context, the properties rank.ac.readfrom and rank.ac.searchin must be set correctly (see PixolutionParserPlugin).

An example for searching by image id 123 with Auto Context:

&pixolution=true&rank.by=id:123&rank.ac=true

Set q param correctly

If a user does not specify any keyword for param q always specify q=*:* to match all docs. Auto Context will then and only then replace this query with associated keywords of the sample image given by rank.by=id:. Do not use something like q=myField:*. Auto Context will not replace this query and the search results will not be reduced to relevant images.