Eppi wrote:Hi all,
I'm new to the forum and have been following this thread with interest. Now I'm just a noob at this (first build still underway), so not as familiar with all the nuances & nuisances of book scanner design as you folks. But I thought I'd add my two cents worth anyway...
I'm following the "New Standard Scanner" build which means that my cameras will each be mounted on a fixed column. However, I am considering incorporating a minor tweak which I hope will help reduce keystoning. The idea is to mount the cameras to each column via a simple sliding (and lockable) mechanism. The mechanism will allow the camera position to be altered at 45Âº to horizontal, along a line which is parallel to the cradle (see blue line in diagram below ( I'm hoping that a diagram actually appears below, if not then I has mucked it up)).
So if the camera is positioned along this blue line so that it is directly over the center of the page, then keystoning should be minimised (along one axis anyway). Distance along the surface of the cradle will then be 1:1 with distance along the sliding camera mount.
This plan appears to be similar to the route that the.traveller is taking (lame pun not intended) just using a different plane of movement. Can anyone see any major problems with my plan? I can see that there will be a bit of extra work initially but if I mark some points along the slide which correspond to known points on the cradle surface then I'm hoping that setup time at the start of each book will be reasonable.
dpc wrote:Has there been a scanner build using a fixed cradle and allowed the platen to shift horizontally as well as move vertically?
If you did this and then attached the cameras to arms attached to the platen (instead of to the base), you would get the page in the same location within the captured image across the entire book scan. You'd minimize the amount of wasted pixels due to cropping and use more pixels on the actual page content which is always a plus.
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