Finished my scanner

Built a scanner? Started to build a scanner? Record your progress here. Doesn't need to be a whole scanner - triggers and other parts are fine. Commercial scanners are fine too.

Finished my scanner

Postby translucent1 » 25 Jul 2010, 17:49

First, let me say thanks to everyone here for sharing your knowledge and ideas. I just finished my scanner today. I only have one of my cameras (Canon A640), but the other one is on the way, and I have an old A520 that's filling in until it gets here.

I built the frame out of 8020 aluminum sections, and the cradle and "light box" are MDF. My goal was to build a machine that's as rigid and precise as possible, with the hope of avoiding any postprocessing steps to correct for rotation, keystoning, etc. I'm quite satisfied with the result. The platen up and down motion is extremely smooth, and I can lift it from any point on its frame without binding or flexing.

The lights are LED spotlights from Ikea. I cut the gooseneck on each light with a hacksaw and mounted them in the light box with cable glands. The light box also contains 5V power for the cameras, and a single light switch to turn everything on.

The cradle is pretty much standard, with left/right and width adjustments. The max book dimensions are 12"x10". Since I'm going to be using this mainly for textbooks, I don't anticipate needing to handle anything larger.

On the software side, I'm using linux for capture and postprocessing, with gphoto2 for triggering/downloading, imagemagick for cropping and contrast adjustment, cuneiform for OCR (output in HOCR format), and then hocr2pdf to create the final searchable pdf. I'm working on a simple GUI that shows the right and left pages as they're captured, similar to what most of the commercial scanners have.

The camera mounts are made of acrylic, and have about 2.5" of up and down adjustment, and scales so that I can accurately set the camera height on each side.

There's a small hinged piece that allows the platen to be held in the up position for convenience. Swapping books or adjusting the cradle was really cumbersome before I added this!

scanner_w_laptop_1.jpg
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scanner_camera_mount.jpg
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scanner_cradle.jpg
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scanner_camera_mount_2.jpg
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scanner_lighting_1.jpg
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scanner_platen_stop.jpg
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scanner_platen_up.jpg
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scanner_software_1.jpg
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translucent1
 
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Re: Finished my scanner

Postby univurshul » 25 Jul 2010, 18:52

Truly Awesome. Killer concept, design. Looks like a tank. Nice and stable, level supports. "Precision" is the word.

Hey, post some captures when you can. I'd like to see how your images produce with lighting output at this level.
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Re: Finished my scanner

Postby translucent1 » 25 Jul 2010, 20:00

Thanks. At the moment I'm working software so that I'll be ready to go when my second camera arrives.
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Re: Finished my scanner

Postby daniel_reetz » 25 Jul 2010, 23:39

holy kamole, that's a slick scanner! can you tell us more about the 80/20 system in terms of design pain and wallet pain? ;)

also, are you monitoring the output of both cameras onscreen? if so, how?

congratulations on a very, very nice build! really looking forward to seeing more of what you do.
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Re: Finished my scanner

Postby translucent1 » 26 Jul 2010, 12:09

The 80/20 extrusions certainly aren't the cheapest building material, but they're really nice for making machine frames like this. You can get pre-cut extrusions on ebay: http://cgi.ebay.com/80-20-T-Slot-Extrusion-10-S-1020-x-20-Long-Taps-AH-/330453623737?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item4cf09223b9#ht_995wt_913 or you can cut them yourself. I used a miter saw with 60 tooth carbide blade, and it cuts this stuff no problem. The various joining plates are also available on ebay, of you're in a hurry you can get everything from http://www.mcmaster.com/#structural-framing/=84o9ho (and pay higher prices).

I'm working on a simple perl-gtk2 application for scanning. It's basically a wrapper around gphoto2 that displays the pages as they're captured, and allows you to re-shoot individual pages. Each time I hit the spacebar it captures and displays the next set of pages.

scanner_screenshot.jpg
scanning app
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You can also see a shadow at the top of the pages from a chair that was sitting behind my scanner.

It's the same idea that unbelift is using: viewtopic.php?f=1&t=357&p=3469&hilit=gphoto2#p3469 but with a GUI
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Re: Finished my scanner

Postby Tim » 26 Jul 2010, 13:26

Wow to the build and especially the software. That's really cool. Too bad so few new camera work with gphoto, since for those that do, that's really nice. But can you say more about the parts you used for the camera mount? That is a truly impressive part and since your camera is held at exactly 45 degrees with a nice range of vertical motion, it's essentially ideal from a quality standpoint.
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Re: Finished my scanner

Postby translucent1 » 26 Jul 2010, 18:28

Thanks!

The camera mounts are made from acrylic, and assembled with weld-on solvent, just like the platen. They slide up and down in the t-slot in the 80/20 extrusions to adjust camera height. I'll take a better photo of them tonight. They were fairly simple to make, I just used a table saw and compound miter saw to cut the parts, and assembled them with a carpenter's square.

gphoto is indeed really nice. It means I can simply flip the power switch, click a button in my software, and the cameras will enter capture mode, set the zoom, white balance, exposure, etc and be ready to take photos within a couple of seconds.
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Re: Finished my scanner

Postby univurshul » 26 Jul 2010, 18:46

Are you scanning with ambient light+ led lights or in the dark? If you scan in the dark, how well do these LEDs perform? Is color balance and reproduction good or are you only concerned with B/W & greytone reproduction/post-processing?
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Re: Finished my scanner

Postby translucent1 » 26 Jul 2010, 19:15

I'll either have to scan in the dark or put some kind of tent over my scanner to block ambient light - I don't want random reflections bouncing around my scanner. I'm not really concerned with color accuracy, but with a custom white balance I don't think I'll have any problems. I haven't actually had a chance to do much scanning yet, but I'm hoping to get my second camera in a couple of days and then I'll be off to the races.
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Re: Finished my scanner

Postby translucent1 » 26 Jul 2010, 22:59

A few pictures of the camera mount. The idea is to hold the camera at a 45 degree angle and allow vertical adjustment. There are two tabs that ride in the t-slot, and a few pieces to keep it from flexing.

camera_mount_1.jpg
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camera_mount_2.jpg
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camera_mount_3.jpg
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