... the heel (pivot) location, the end of the blade planing, and the blade tip (point). On the right the mark is the end of the blade planing (where the rails diverge). All these are as best I can judge on a rather indistinct photo -- in particular the end-of-planing on both sides is a best guess. This is unfortunate because it is the only location showing on both sides, and at least one such location is needed to align the correction grid. gimp4.png This is a zoomed-in screenshot from Gimp, showing the perspective correction grid. I have dragged the grid corners to align the vertical grid lines down the rail edges, and also one horizontal grid line is aligned across between the end-of-planing green marks where they intersect the gauge lines. Strictly speaking we need another location to align the horizontal grid lines square across the rails and complete a full rectangle. The best that can be managed here is to align a grid line across the far ends of the ...