PERCEPT Indoor Wayfinding for Blind and Visually Impaired Users: Navigation Instructions Algorithm and Validation Framework Topics: Ambient Intelligence; Assistive Technology and Adaptive Systems; Autonomy and Active Ageing; Smart Environments and Housing In Proceedings of the 3rd International Conference on Information and Communication Technologies for Ageing Well and e-Health ICT4AWE - Volume 1, 143-149, 2017 , Porto, Portugal