Table 2.

Repeatability of UrbanCrowns estimates of crown volume and density for sugar maple (Acer saccharum) photographed at four horizontal distances equal to multiples (1.5×, 2.0×, 2.5×, 3.0×) of their individual heights. *, **, ***, and **** denote average absolute differences between paired photo distance intervals that are significantly greater than 0%, 1%, 5%, and 10%, respectively (n = 10 per interval).

Tree Attribute	Trunk Diameter Class (cm)
Tree Attribute	1–15	16–30	31–45	46–60	>60
Crown Volume
1.5× – 2.0×	**^z	**	***	***	***
1.5× – 2.5×	**	**	***	***	***
1.5× – 3.0×	**	***	****	***	***
2.0× – 2.5×	**	**	**	**	**
2.0× – 3.0×	**	**	**	**	**
2.5× – 3.0×	**	**	**	**	*
Crown Density
1.5× – 2.0×	**	*	*	*	*
1.5× – 2.5×	**	**	*	*	*
1.5× – 3.0×	**	**	*	*	*
2.0× – 2.5×	*	*	*	*	*
2.0× – 3.0×	**	*	*	*	*
2.5× – 3.0×	**	*	*	*	*

^zDifferences between paired photo distance intervals calculated as l(a – b) ÷ a × 1001. Values tested against hypothesized means (0%, 1%, 5%, and 10%) using one-sample t-tests at α = 0.05.