  Spatial patterns and processes of cities can be described with various
entropy functions. However, spatial entropy always depends on the scale of
measurement, and it is difficult to find a characteristic value for it. In
contrast, fractal parameters can be employed to characterize scale-free
phenomena. This paper is devoted to exploring the similarities and differences
between spatial entropy and fractal dimension in urban description. Drawing an
analogy between cities and growing fractals, we illustrate the definitions of
fractal dimension based on different entropy concepts. Three representative
fractal dimensions in the multifractal dimension set are utilized to make
empirical analyses of urban form of two cities. The results show that the
entropy values are not determinate, but the fractal dimension value is certain;
if the linear size of boxes is small enough (e.g., <1/25), the linear
correlation between entropy and fractal dimension is clear. Further empirical
analysis indicates that fractal dimension is close to the characteristic values
of spatial entropy. This suggests that the physical meaning of fractal
dimension can be interpreted by the ideas from entropy and scales and the
conclusion is revealing for future spatial analysis of cities. Key words:
fractal dimension; entropy; mutlifractals; scaling; urban form; Chinese cities
