Vector Silhouette Extraction for Generating Blueprint

Silhouette extraction as the first step in many computer graphics techniques, like non-photorealistic rendering, has attracted more and more people working on it. In this paper, we proposed an algorithm to extract vector silhouette lines for generating blueprint of culture heritages. It includes two stages. In the silhouette detection stage, we use Brute Force [1] method to guarantee all silhouette edges will be found In the visibility determination stage, we proposed a hybrid algorithm to do hidden line removal. With the help of three depth buffers, we generate analytic vector lines for visible silhouette in real data, which can be used for measurement. We have tested several polygonal models on our system to verify the efficiency. We can get the vector silhouette edges for generating blueprint, and we can measure the features in real data. Compare to other hybrid algorithms, our rendering results have no disconnected lines. The time complexity of our algorithm is less than Appel´s [2] algorithm which is frequently used in the context of silhouette extraction algorithms. The vector silhouette images are satisfied even when enlarge the edge lines many times.