You should be able to open it with with the free adobe reader. Just click on the image and then you can rotate it and so on. It has some weird greyish colours but it's good enough to see the whole keyboard and choose good angles.
Orthogonal means just that all parallel lines on the keyboard are also parallel on the picture, opposed to perspective, where they run to one or two points.
I think the first set looks a bit better from this angle.
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