  Recently, public displays such as liquid crystal displays (LCDs) are often
used in urban green spaces, however, the display devices can spoil green
landscape of urban green spaces because they look like artificial materials. We
previously proposed a green landscape-friendly grass animation display method
by controlling a pixel-by-pixel grass color dynamically. The grass color can be
changed by moving a green grass length in yellow grass, and the grass animation
display can play simple animations using grayscale images. In the previous
research, the color scale was mapped to the green grass length subjectively,
however, this method has not achieved displaying the grass colors corresponding
to the color scale based on objective evaluations. Here, we introduce a dynamic
grass color scale display technique based on a grass length. In this paper, we
developed a grass color scale setting procedure to map the grass length to the
color scale with five levels through image processing. Through the outdoor
experiment of the grass color scale setting procedure, the color scale can
correspond to the green grass length based on a viewpoint. After the
experiments, we demonstrated a grass animation display to show the animations
with the color scale using the experiment results.
