3D Line Drawing for Archaeological Illustration

Archaeological line drawing is an essential component of an archaeological report, which can not only illustrate heritage objects, but also record their accurate geometric measurements. In this paper, we propose a multi-scale approach to generating 3D line drawings on meshes reconstructed from raw scanning data of objects in grottoes. To reduce redundant lines detected on the rough and noisy surfaces, we first construct the discrete multi-scale representation of a given model based on random walks. The transition probability matrices are defined by studying the local variation around each vertex on the mesh. Furthermore, it is difficult to determine a single optimal scale for the whole mesh, because different scales are localized on the surface. A method for local scale selection is proposed based on the minimum description length (MDL) principle. Finally, we generate the line drawing using ridges or valleys detected with the selected scales. Experimental results show that the multi-scale 3D lines can well depict the shapes of heritage objects. Compared with the traditional manual method, our method is more accurate and convenient. Moreover, the offsets of detected lines are less than those using mesh smoothing methods. As assistance in archaeological mapping, our computer-generated line drawings can decrease the time cost to a large extent.