CHOP: Counterfactual Human Preference Labels Improve Obstacle Avoidance in Visuomotor Navigation Policies. - Gershom Seneviratne; Jianyu An; Vaibhav Shende; Sahire Ellahy; Yaxita Amin; Kondapi Manasanjani; Samarth Chopra; Jonathan Deepak Kannan; Dinesh Manocha (CoRR, 2026)