3D Searching

          The 3D-search system uses algorithms to convert the selected or drawn image-based query into amathematical model that describes the features of the object being sought. This converts drawings andobjects into a form that computers can work with. The search system then compares the mathematicaldescription of the drawn or selected object to those of 3D objects stored in a database, looking forsimilarities in the described features.

          The key to the way computer programs look for 3D objects is the voxel (volume pixel). A voxel is a set of graphical data-such as position, color, and density-that defines the smallest cubeshaped building blockof a 3D image. Computers can display 3D images only in two dimensions. To do this, 3D renderingsoftware takes an object and slices it into 2D cross sections. The cross sections consist of pixels (pictureelements), which are single points in a 2D image. To render the 3D image on a 2D screen, the computerdetermines how to display the 2D cross sections stacked on top of each other, using the applicableinterpixel and interslice distances to position them properly. The computer interpolates data to fill ininterslice gaps and create a solid image.

          True 3D search systems offer two principal ways to formulate a query: Users can select objects from acatalog of images based on product groupings, such as gears or sofas; or they can utilize a drawingprogram to create a picture of the object they are looking for. or example, Princeton's 3D search engineuses an application to let users draw a 2D or 3D representation of the object they want to find.