Can a search be triggered directly from the URL, not being through the tag cloud or search form ?
Yes, this is possible. A search can now be done directly on the image database without going through the search form or tag cloud. All you have to do is to form URLs like http://wwww.mysite.com/image_library?tags=car+plane+airport, forming your tag list using tag slugs. In that example, the page image_library is the one set with the search form and/or tag cloud, that will be displayed with the tag cloud and/or search form, clean of any search result if requesting http://wwww.mysite.com/image_library. A tag slug is the tag name with no accent and spaces replaced by hyphens. For instance, the tag “l’automne en forêt” becomes “l-automne-en-foret”. By default the result page produced by explicit search URL will not hold any tag cloud or search form. Anyhow you can request to have this capability on top of the search results by forming URL like : http://wwww.mysite.com/image_library?tags=car+plane+airport&display=cloud. Possible values for the display argument are : cloud, form, combined.
