快速原型（Rapid Prototyping，RP）是一種新興的電腦控制製造系統，在工業界使用已日漸普及。RP系統主要是藉由CAD軟體建構出實體模型，再轉換成STL格式，經由RP系統以疊層製造（Layered Manufacturing）的方式產生工件。而STL格式本身存在資料重複記錄性與精度不足的缺點，因此近幾年逐漸發展出直接切層理論，就目前直接切層發展狀況，主要侷限於應用特定軟體做切層處理、通用性不足以及使用簡單圖元資訊做切層後的記錄等缺點。
本研究提出以B-Rep結構的IGES檔案格式實體模型，依照IGES檔案中幾何圖元資訊的不同，分為平面與平面、圓弧曲面與平面和NURBS曲面與平面三種曲面做切層計算，達到提高切層輪廓成型精度、具通用性與避免STL格式轉換。在模擬實驗中，利用本研究所提之方法，與STL切層法做比較，由結果可知，確實提高成型精度，並獲得愈趨近於原始CAD模型的實體。

Rapid Prototyping（RP） was the new manufactured system of computer control. It was more popular every day in the industry. We create a 3D solid model with CAD, then translate to STL format for RP system and fabricate by layered manufacturing（LM）. Disadvantages of the STL format are having redundancy and accuracy problems. The field of direct slicing for LM has been researched for some time. In reality, direct slicing confines applications to particular software, less universal and uses simple geometric entities.
This research uses an IGES solid model based on B-Rep structure. According to the differential geometric entity, the intersection of two surfaces can be divided into plane/plane、arc surface/plane and NURBS surface/plane, differential methods were taken to compute their intersection. The methods can be enhanced accuracy, universal and avoided data translation from CAD to STL. In this paper, we use our method to compare with STL slicing algorithm. These results show the accuracy of sliced can be enhanced. And to make the part produced by the RP machine nearly the original CAD model as possible.
Keywords：Rapid Prototyping、Direct Slicing、B-Rep

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