survey_animation = function()
	print('Viewport at start of survey animation', Viewport.x, Viewport.y, Viewport.zoom)
	local initial_viewport = copy_viewport(Viewport)
	animate_viewport_to(--[[global viewport]] nil)
	animate_viewport_to(initial_viewport)
	print('Viewport at end of survey animation', Viewport.x, Viewport.y, Viewport.zoom)
end