Towards cognitive evaluation of computer-drawn sketches

This paper seeks to raise visual comparisons beyond subjective opinions into evidence-based visual reasoning. It provides an informal deductive analysis of the marks in sketches derived with two competing line-filtering algorithms. 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 debate. Although the proposed cognitive computation was not automated, it justified the rejection of the Douglas–Peucker algorithm in favour of Visvalingam's algorithm in subsequent research within the Cartographic Information Systems Research Group (CISRG).