Table 2.

Coding of global features.

Global features		Examples
Observation perspectives	Front view 1	Front View 1
	Side view 2	Side View 2
	Plan view 3	Plan View 3
	Upward view 4	Upward View 4
	Mixed view 5	Mixed View 5
Baseline	Without baseline 1	Baseline 1
	Objects drawn on baseline 2	Baseline 2
	Baseline divided the space area 3	Baseline 3
Comparison	Wrong comparison 0	Wrong Comparison 0
	Distance comparison 1	Distance Comparison 1
	Proportion comparison 2	Proportion Comparison 2
	With distance and proportion comparison 3	Distance and Proportion Comparison 3