jay wrote:Shot 01 shows how I want my camera to shoot a flat image without skew. This requires the shot angle to match the angle of the cradle
dpc wrote:Does this mean that the camera position should be adjusted over the course of a scanning a thick book?
spamsickle wrote:jay wrote:Shot 01 shows how I want my camera to shoot a flat image without skew. This requires the shot angle to match the angle of the cradle
For me, this says it all. I wouldn't have the patience to do a lot of mathematical calculations before shooting each book, but I'm essentially doing the same thing you're doing.
I use tripods instead of having a camera mount built into my scanner, but the principles are the same. There are three "rotations" to consider. The Mercury astronauts called them "roll, pitch, and yaw". If you're holding a camera, roll is raising the left or right side of the camera. I don't want any roll; it would make my image appear tilted. Yaw is rotating your head from left to right. I don't want any yaw either; it would give me "left to right" keystoning. Pitch is nodding your head. I want the pitch to be 45 degrees every time, to match the angle of my cradle.
I set the head of my tripod to have a 45-degree pitch, attach the camera, and then raise or lower it just as you say until the book I'm shooting is positioned in the viewfinder. The main thing is getting the 45-degree thing right. Your camera mounts should take care of enforcing the no-roll, no-yaw, 45-degree-pitch automatically, so all you have to adjust is the zoom factor and the height to get a full-frame rectilinear image.
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