This paper explores the perceptual quality of visual coding designs for 3D charts in data visualization. With the increasing use of 3D-style interfaces, 3D charts such as pie charts and bar charts are gaining popularity due to their enhanced visual appeal and higher user experience. However, the design guidelines for 3D chart visual coding, particularly regarding transparency, viewing angles, and category quantities, remain under explored. Inappropriate design choices in these areas can lead to increased cognitive load, complicating data interpretation. This study aims to assess optimal visual coding strategies for the typical 3D pie chart through a behavioral experiment, offering recommendations for design to reduce cognitive strain and improve overall visual quality.