Sketcha: a captcha based on line drawings of 3D models.

@inproceedings{ross-2010-sketcha, author = {Steven A. Ross and J. Alex Halderman and Adam Finkelstein}, editor = {Michael Rappa and Paul Jones and Juliana Freire and Soumen Chakrabarti}, title = {{Sketcha: a captcha based on line drawings of 3D models}}, booktitle = {{Proceedings of the 19th International Conference on World Wide Web, WWW 2010, Raleigh, North Carolina, USA, April 26-30, 2010}}, pages = {821--830}, publisher = {ACM}, year = {2010}, url = {https://doi.org/10.1145/1772690.1772774}, doi = {https://doi.org/10.1145/1772690.1772774} }