Table 1 Formulas and explanations for each indicator.

From: A novel framework integrating GeoAI and human perceptions to estimate walkability in Wuhan, China

First-level indicators

Second-level indicators

Formula

Quantitative definition based

on street view data

Greenness

Vegetation coverage rate

\({G_i}=\frac{{\sum\nolimits_{{i=1}}^{4} {{V_i}} }}{4}\)

Vi is the number of vegetation pixels;

Openness

Sky visible ratio

\({O_i}=\frac{{\sum\nolimits_{{i=1}}^{4} {{S_i}} }}{4}\)

Si is the number of sky pixels;

Crowdedness

Space occupancy rate

\({C_i}=\frac{{\sum\nolimits_{{i=1}}^{4} {({M_i}+{P_i})} }}{4}\)

Mi is the number of non-motor vehicles pixels;

Pi is the number of people pixels;

Traffic flow

\({T_{traffic}}=\left\{ {\begin{array}{*{20}{c}} {0,}&{smooth} \\ {1,}&{slow} \\ {2,}&{congestion} \end{array}} \right.\)

0,1,2 mean different levels of traffic flow;

Safety

Proportion of sidewalks

\({P_i}=\frac{{\sum\nolimits_{{i=1}}^{4} {P{1_i}} }}{{\sum\nolimits_{{i=1}}^{4} {{R_i}} }}\)

P1i is the number of sidewalk pixels;

Ri is the number of road pixels;

Road safety facilities

\({F_{facility}}=\left\{ {\begin{array}{*{20}{c}} {0,}&{deficient} \\ {1,}&{inadequate} \\ {2,}&{relatively{\text{ }}perfect} \\ {3,}&{complete} \end{array}} \right.\)

0,1,2,3 mean the degree of

perfection of road safety facilities;

Parking phenomenon on

the sidewalk

\({F_{park}}=\left\{ {\begin{array}{*{20}{c}} {0,}&{exist} \\ {1,}&{non - exist} \end{array}} \right.\)

0,1 mean whether the sidewalk

parking phenomenon exists.