Figure 2
From: Simplifying the propagation environment representation for LMS channel modelling

Description of the 4 different classes of details. Class 1, green, contains only the flat parts of the walls. Class 2, yellow, contains windows and balconies. Class 3, orange, contains shutters and guardrails. Class 4, red, contains all smaller details. Each class of detail roughly reproduces the characteristics of each level of detail.