Method and apparatus for forming three-dimensional objects using line width compensation with small features retention

摘要

Rapid prototyping and manufacturing (e.g. stereolithography) methods and apparatus are disclosed that form objects with enhanced accuracy and small feature retention. Techniques for offsetting cross-sectional boundary data to at least partially accommodate for solidification width induced in a medium by a beam of radiation are provided. One technique uses repeated small offsets to yield an effective offset of a desired amount. A second technique uses displacement vectors to determine where and to what extent to offset the boundary segments. The offset amount for each vertex is determined based on a combination of the (1) the vertex angle, and (2) a predefined variable offset criteria which is different for at least two predefined ranges of angles. A third technique converts a single boundary segments into a plurality of offset boundary segments when the single boundary segment can not undergo the full desired offset without violating another offsetting rule.