On today's Web, designers take huge efforts to create visually rich websites that boast a magnitude of interactive elements. Contrarily, most web information extraction (WIE) algorithms are still based on attributed tree methods which struggle to deal with this complexity. In this paper, we introduce a versatile model to represent web documents. The model is based on gestalt theory principles---trying to capture the most important aspects in a formally exact way. It (i) represents and unifies access to visual layout, content and functional aspects; (ii) is implemented with semantic web techniques that can be leveraged for i.e. automatic reasoning. Considering the visual appearance of a web page, we view it as a collection of gestalt figures---based on gestalt primitives---each representing a specific design pattern, be it navigation menus or news articles. Based on this model, we introduce our WIE methodology, a re-engineering process involving design patterns, statistical distributions and text content properties. The complete framework consists of the UOM model, which formalizes the mentioned components, and the MANM layer that hints on structure and serialization, providing document re-packaging foundations. Finally, we discuss how we have applied and evaluated our model in the area of web accessibility.

Fast technological advancements and little compliance with accessibility standards by Web page authors pose serious obstacles to the Web experience of the blind user. We propose a unified Web document model that enables us to create a richer browsing experience and improved navigability for blind users. The model provides an integrated view on all aspects of a Web page and is leveraged to create a multi-axial user interface.

We demonstrate a flight meta-search engine that is based on the Metamorph framework. Metamorph provides mechanisms to model web forms together with the interactions which are needed to fulfil a request, and can generate interaction sequences that pose queries using these web forms and collect the results. In this paper, we discuss an interesting new feature that makes use of the forms themselves as an information source. We show how data can be extracted from web forms (rather than the data behind web forms) to generate a graph of flight connections between cities.

Form mapping is the key problem that needs to be solved in order to get access to the hidden web. Currently available solutions for fully automatic mapping are not ready for commercial meta-search engines, which still have to rely on hand crafted code and are hard to maintain.

Traditionally, information extraction from web tables has focused on small, more or less homogeneous corpora, often based on assumptions about the use of tags. A multitude of different HTML implementations of web tables make these approaches difficult to scale. In this paper, we approach the problem of domain-independent information extraction from web tables by shifting our attention from the tree-based representation of web pages to a variation of the two-dimensional visual box model used by web browsers to display the information on the screen. The thereby obtained topological and style information allows us to fill the gap created by missing domain-specific knowledge about content and table templates. We believe that, in a future step, this approach can become the basis for a new way of large-scale knowledge acquisition from the current “Visual Web.”

In the AllRight project, we are developing an algorithm for unsupervised table detection and segmentation that uses the visual rendition of a Web page rather than the HTML code. Our algorithm works bottom-up by grouping word bounding boxes into larger groups and uses a set of heuristics. It has already been implemented and a preliminary evaluation on about 6000 Web documents has been carried out.