© 2015 IEEE. Emerging and continuing developments in ubiquitous computing and Internet of Things have brought novel opportunities to develop context-aware indoor navigation system. However, lacking of formal, directly applicable spatial models was one of the reasons made indoor navigation systems not world wide practicable in the physical phenomenon. Especially, indoor spatial model that takes into account diverse accessibility semantics could be a fundamental component for generating indoor routes that can be referenced by users with specific needs or preferences, assisting their indoor mobility. For the purpose of assisting indoor mobility, we firstly clarified and categorized diverse features of facilities that should be considered as accessibility semantics. We proposed an indoor spatial model fine-grained designed with accessibility semantics that is directly applicable for indoor routing. Based on our proposed model, we developed a systematic approach to generate indoor path descriptions for implementation. The visually impaired oriented case study was conducted for evaluating feasibility and effectiveness of our proposal, the promising result will be stated at last.