LAYER COMPARISON TECHNIQUES IN STEREOLITHOGRAPHY

A method of and apparatus for slicing a three-dimensional object representation into a plurality of layer representations. The layer representations are subsequently used to form the object layer-by-layer from a solidifiable material by stereolithography (711). If not already provided in the object representation, a plurality of layer boundary representations are first formed, and then the boolean difference (17), of successive layer boundary representations are computed to derive boundaries of up and down-facing regions, enabling different cure parameters to be specified for these different regions. In another method, the depth of the curable material within the objet underlying a selected area element is determined and compared to the depht to the minimum solidification depth of the material. The area element is exposed to solidifying synergistic stimulation only if the depth of the material equals or exceeds the minimum solidification depth. A next layer is created over the first layer without curing the first layer, if the depth is less than the minimum solidification depth. Another method and apparatus (714) eliminates or substantially reduces curling effects in stereolithographically formed objects. Synergistic stimulation is applied to a curable material to form a three-dimensional object through the build up of successive layers.