The photographer metaphor for content based image retrieval

Image database systems have been widely studied in the last few years. Having to deal with visual information, a great effort has also been put into designing and implementing user interfaces for retrieval engines. Most of those interfaces allow the user to specify the query through visual examples, either by feeding a complete image to the system or by drawing some coloured/textured patches on a sketchpad. However, the “query by example” paradigm can be inadequate in many contexts, due to the difficulty for many users to paint significant examples and the impossibility, in many cases, of reproducing complex scenes. 3D interfaces and virtual reality-based interaction paradigms offer new possibilities to overcome these limitations. In the prototype system presented here, the user is allowed to navigate a 3D scene. While navigating the virtual world, the user is given the opportunity of taking some photographs used to query by content a database of images