In many applications of spatial or temporal visualization, glyphs provide an effective means for encoding mul- tivariate data objects. However, because glyphs are typically small, they are vulnerable to various perceptual errors. In data communication, the concept of Hamming distance underpins the study of codes that support error detection and correction by the receiver without the need for corroboration from the sender. In this extended abstract, we outline a novel concept of quasi-Hamming distance in the context of glyph design. We discuss the feasibility of estimating quasi-Hamming distance between a pair of glyphs, and the minimal Hamming distance for a glyph set. This measurement enables glyph designers to determine the differentiability between glyphs, facilitating design optimization by maximizing distances between glyphs under various constraints (e.g., the available number of visual channels and their encoding bandwidth).