在電腦圖學最常用的轉換是易凡轉換[2]，因這種轉換有一個簡單的格式，共有4種基本的轉換1.平移 2.放大縮小 3.旋轉 4.變形。任何一個轉換是由一個或數個基本轉換所組合成。在三度空間中先定一條線(圖1)，對Z軸旋轉360度將得到像甜筒外殼一樣的圖形(圖2)，叫做懷爾凡模式(wireframe model)。依照所站的角度不同而顯示出看得見部份，將此看得見的部份再依易凡轉換轉成不同的圖形。
The most common transformations used in Computer Graphics are the Affine Transformations, for they have a simple form. There are four elementary trans-formations: 1. Translation 2.scaling 3.rotation 4.shearing. Any transformation is the combinations of one or more than one elementary transformations. In three di-mensional space to generate wire and rotate 360。 Around Z axis, will get a shape like a crust of ice cream. We call it “Wireframe Model”. Depending on the different site that you stand, you can see the visible part, and then using Affine Transformation to translate the visible part to different shape.
