  Nowadays, Vision Transformer (ViT) is widely utilized in various computer
vision tasks, owing to its unique self-attention mechanism. However, the model
architecture of ViT is complex and often challenging to comprehend, leading to
a steep learning curve. ViT developers and users frequently encounter
difficulties in interpreting its inner workings. Therefore, a visualization
system is needed to assist ViT users in understanding its functionality. This
paper introduces EL-VIT, an interactive visual analytics system designed to
probe the Vision Transformer and facilitate a better understanding of its
operations. The system consists of four layers of visualization views. The
first three layers include model overview, knowledge background graph, and
model detail view. These three layers elucidate the operation process of ViT
from three perspectives: the overall model architecture, detailed explanation,
and mathematical operations, enabling users to understand the underlying
principles and the transition process between layers. The fourth interpretation
view helps ViT users and experts gain a deeper understanding by calculating the
cosine similarity between patches. Our two usage scenarios demonstrate the
effectiveness and usability of EL-VIT in helping ViT users understand the
working mechanism of ViT.
