Why did eighteenth-century artists in kyoto begin to use western methods of shading and perspective?

The correct answer is to meet the demand of patrons interested in three - dimensional effects enhanced by optical device

People who commissioned works of art and those who participated in the public life became enchanted with the western achievements in art such as the development of perception and scaling and proportion and similar things so they started bothering artists in Japan to learn from them and incorporate it in their works.