Yang Zhao Dang-en Xie Dan Xu Tour into Virtual Environment in the Style of Pencil Drawing. 628-635 2008 Edutainment http://dx.doi.org/10.1007/978-3-540-69736-7_67 conf/edutainment/2008 db/conf/edutainment/edutainment2008.html#ZhaoXX08