A method reads information of a three-dimensional (3D) product model and a light source model, and meshes the product model by multiple space triangles. The method further sets illumination parameters based on the information of product model and the light source model, simulates illuminated environment based on the illumination parameters, and projects the product model to a two-dimensional (2D) plane under the illuminated environment. 2D triangles matching the space triangles and 2D measurement points matching the 3D measurement points are determined in the 2D plane, and a measurement region is determined based on the 2D measurement points. Then, the 2D triangles in the measurement region are given colors based on illuminated effect produced by the illuminated environment, and point-selection tools are created for the 2D measurement points. At last, an off-line program is generated according to information of the measurement region and the point-selection tools.