Table 2.

Spatial indicators in mountainous historic urban parks.

Hierarchy	Category	Description	Calculation method*
Visual	Openness	Percentage of prospect view pixels ($\mathit{\text{PVPixel}}$) of the street view image	$\mathit{\text{Openness}}=\frac{\mathit{\text{PVPixel}}}{P}$
	Green view index	Percentage of greenery pixels ($\mathit{\text{GreeneryPixel}}$) of the street view image	$\mathit{\text{Green view index}}=\frac{\mathit{\text{GreeneryPixel}}}{P}$
	Concealment	Percentage of obstructed pixels ($\mathit{\text{ConcealmentPixel}}$) in the street view image	$\mathit{\text{Concealment}}=\frac{\mathit{\text{ConcealmentPixel}}}{P}$
	Material hardness ratio	Ratio of the percentage of soft material pixels ($\mathit{\text{SoftMaterialPixel}}$) to the percentage of hard material pixels ($\mathit{\text{HardMaterialPixel}}$) in the street view image	$\mathit{\text{Material hardness ratio}}=\left(\frac{\mathit{\text{SoftmaterialPixel}}}{\mathit{\text{HardMaterialPixel}}}\right)\times 100\%$
	Retaining walls ratio	Percentage of retaining walls pixels ($\mathit{\text{RetainingwallsPixel}}$) in the street view image	$\mathit{\text{Retaining walls ratio}}=\frac{\mathit{\text{RetainingwallsPixel}}}{P}$
	Green slopes ratio	Percentage of retaining walls pixels ($\mathit{\text{GreenslopesPixel}}$) in the street view image	$\mathit{\text{Green slpoes ratio}}=\frac{\mathit{\text{GreenslopesPixel}}}{P}$
	Proportion of trees	Percentage of tree canopies pixels ($\mathit{\text{TreesPixel}}$) in the street view image	$\mathit{\text{Proportion of trees}}=\frac{\mathit{\text{TreesPixel}}}{P}$
	Elevation difference	The elevation drop gradient near the adjacent node.	$\mathit{\text{Elevation difference}}={\mathit{Ele}}_i-\mathit{El}{e}_{\mathit{ni}}$
Acoustic	Natural sound	Average percentage of naturalsound ($T_{\mathit{ns}}$) duration in the recorded segment	$\mathit{\text{Natural sound}}=\frac{1}{n}\sum _{i=1}^n\frac{T_{\mathit{ws},i}}{T_{\mathit{\text{total}},i}}$
	Artificial sound	Average percentage of artificial sound ($T_{\mathit{as}}$) duration in the recorded segment	$\mathit{\text{Artificial sound}}=\frac{1}{n}\sum _{i=1}^n\frac{T_{\mathit{ws},i}}{T_{\mathit{\text{total}},i}}$
	Mechanic sound	Average percentage of mechanic sound duration ($T_{\mathit{ms}}$) in the recorded segment	$\mathit{\text{Mechanic sound}}=\frac{1}{n}\sum _{i=1}^n\frac{T_{\mathit{bs},i}}{T_{\mathit{\text{total}},i}}$

*P is the total pixels of the street view image, “T_total” is the total number of recorded segments.