Towards cognitive evaluation of computer-drawn sketches

This paper seeks to raise visual comparisons beyond subjective opinions int o evidence-based visual reasoning. It provides an informal deductive analys is of the marks in sketches derived with two competing line-filtering algor ithms. This prompted the novel speculation that the visual system might be placing some types of anomalies in the foreground of mental 3D space, where they can be ignored. A brief survey is provided to encourage informed deba te. Although the proposed cognitive computation was not automated, it justi fied the rejection of the Douglas-Peucker algorithm in favour of Visvalinga m's algorithm in subsequent research within the Cartographic Information Sy stems Research Group (CISRG).