Free-viewpoint　video　(FVV)　systems　allow　the　viewers　to　freely　change　the　viewpoints　of　the　scene.　In　such　systems,　view　synthesis　and　compression　are　the　two　main　sources　of　artifacts　influencing　the　perceived　quality.　To　assess　this　influence,　quality　evaluation　studies　are　often　carried　out　using　conventional　displays　and　generating　predefined　navigation　trajectories　mimicking　the　possible　movement　of　the　viewers　when　exploring　the　content.　Nevertheless,　as　different　trajectories　may　lead　to　different　conclusions　in　terms　of　visual　quality　when　bench-marking　the　performance　of　the　systems,　methods　to　identify　critical　trajectories　are　needed.　This　paper　aims　at　exploring　the　impact　of　exploration　trajectories　＇defined　as　hypothetical　rendering　trajectories　(HRT)]　on　the　perceived　quality　of　FVV　subjectively　and　objectively,　providing　two　main　contributions.　First,　a　subjective　assessment　test　including　different　HRTs　was　carried　out　and　analyzed.　The　results　demonstrate　and　quantify　the　influence　of　HRT　in　the　perceived　quality.　Second,　we　propose　a　new　full-reference　objective　video　quality　assessment　measure　to　objectively　predict　the　impact　of　HRT.　This　measure,　based　on　sketch-token　representation,　models　how　the　categories　of　the　contours　change　spatially　and　temporally　from　a　higher　semantic　level.　Performance　in　comparison　with　existing　quality　metrics　for　the　FVV　highlight　promising　results　for　the　automatic　detection　of　most　critical　HRTs　for　the　benchmark　of　immersive　systems.