Thursday, September 10, 2009

Experimental content based retrieval engine which operates within a real time 3D virtual reality environment.

This system presents the idea of content based retrieval of 3D models within a VR environment. A 3D reconstruction of a part of the old city of Xanthi has been used as a test-bed 3D scene. Within this environment the user can perform a virtual walkthrough and by clicking on objects the system performs aquery-by-example to a database and retrieves the coordinates of similar objects that might exist within the 3D scene. Animated arrows are then presented over similar objects while the user can monitor on the top map the similarity ranking of the retrieved objects.
At the moment the system uses our 3D descriptors which are designed for vessels and generally surfaces of revolution and thus the available objects are limited to bottles, flower-pots,etc. With the use of other 3D shape descriptors the system can be expanded for other types of objects such as architectural structures, facade features, etc.
It should be mentioned that the 3D scene is manually segmented into separated 3D model entities which properties such as their digital shape signatures (descriptors), their coordinates within the 3D space and other information are encoded into metadata within a native XML database and when the 3D scene is loaded those are loaded progressively and located to their positions according to their metadata.More specifically a left click on an object initiates a query-by-example call which forwards the object's id to the database. The database compares the digital signatures of the query-object against all other scene objects using a similarity metric and returns a sorted (based-on-shape similarity) list with the id's of the similar objects.The system is based on PHP technology and on the native XML database eXist. The 3D reconstruction of a part of the old city of Xanthi has been modelled using Blender and the web based virtual walkthrough is based on Quest 3D technology which works on IE web browser.
To enter the 3D scene using an IE browser click on the following link Take me to the old city of Xanthi (pop up window) or you can watch a small video demo on youtube.

Additional material related to this project can be found at the following links

3D Reconstruction of the old city of Xanthi
On 3D Reconstruction of the old city of Xanthi (Journal of Cultural Heritage)
Process Evaluation of 3D Reconstruction methodologies targeted to web based VR (CIPA 2007)
Experimental 3D Pottery Content Based Retrieval Engine

No comments: