fix sample positions (imagery was skewed by 0.5 pixels at bottom left tile corner)
fix sample positions (imagery was skewed by 0.5 pixels at bottom left tile corner)

seanisom/vtp,markraz/vtp,seanisom/vtp,seanisom/vtp,markraz/vtp,markraz/vtp,seanisom/vtp,markraz/vtp,markraz/vtp,seanisom/vtp