Abstract: A new simple method to obtain contour plot of temperature distribution in two dimensional scalar valued fields is presented in this paper.The parent element is divided into four sub-areas，and the natural coordinates of the vertices of the sub-areas and the shape functions are used to calculate the temperature at the vertices of corresponding sub-areas in real coordinate system.The temperature at the vertices can be utilized to determine whether an isothermal line goes through the sub-area or not.The sub-areas that an isothermal line goes through will be gradually subdivided into smaller and smaller sub-areas until the sizes of the bounding rectangles of sub-areas in real coordinate system are small than or equal to that of a pixel.Theory analysis and examples illustrate that the suggested method is simple，accurate，and easily implemented.

Key words: contour, visualization, finite element method, temperature field

摘要： 等值线是二维标量场可视化的一种主要手段，提出一种画二维单元等值线的简单方法。首先把母元等分成4个子块，然后利用子块顶点的自然坐标和单元的形函数，求出实际单元中对应子块的顶点温度，利用子块顶点温度判断是否有等值线通过。对于有等值线通过的子块，求出其包围盒的尺寸，如果小于等于一个像素，则把对应的像素设置为相应的颜色，否则，在母元中把子块继续4等分，直到实际坐标系中子块的包围盒尺寸小于一个像素为止。应用实践表明，这种方法原理简单，精度高，易于编写程序。

关键词: 等值线, 可视化, 有限单元法, 温度场