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View Full Version : Photoshop Tutorial Request: How to paste together large drawings scanned in pieces



psyekl
03-08-2010, 02:58 PM
I tend to draw my maps by hand with the intention of them being reproduced at a smaller size and this causes a problem with the originals being far too large to be scanned in in just one pass. I've recently purchased a new scanner and a copy of PS, but I still have no idea how to reconstitute the image from the multiple image files so that I can work on it digitally. I've heard that it isn't too difficult but I haven't a clue where to start. A quick tutorial or a link to one would be greatly appreciated :)

Steel General
03-08-2010, 03:53 PM
I believe there is a program called HUGIN(?) that will "stitch" the multiple images together into one. Which could then be pulled into photoshop.

OldGuy
03-08-2010, 05:02 PM
I've had to do this a few times and I agree that it isn't difficult exactly. But I've never been 100% happy with the results either. The big thing for me was that the various pieces each had an extremely small amount of rotation. Too little to adjust out digitally but enough to affect how the pieces lined up.

There was also a problem with stretching. I once scanned in the original greyhawk map. It was two 22" x 34" posters, each folded in half three times which made each section 8.5" x 11". That was a perfect size for scanning but the folds caused subtle stretching that distorted the image (again, only very slightly).

What I found that helped reduce both problems was to cut up the original before scanning. I didn't do this with the greyhawk map but I did with another project. This reduced the distortion effect caused by folding and gave me common edges between the pieces to use to align them up with each other. By setting the same cut edge against the scanner edge, the rotation was as close to identical between the pieces as I could get.

If you don't want to cut up the original (understandable!) I think the key is to match the rotation as closely as you can. Also, it may help to lay the original on a flat surface and press it flat with heavy books for a day prior to scanning. That will help work out any deformations in the paper that might have occurred during the drawing process or from rolling it up, etc.

hth

ZleapingBear
03-08-2010, 05:18 PM
This migth sounds odd. but i have chosen another way... its not the bests. but i works for me... i used a hell of alot momon to get my self a camara with enough magapix. (15mgpix minimum is minimum for this) made a ligth room (white romme with alot of dim ligths in all directions. and photographed the maps. this removes one problem. but creates another... you simply cant get a camara with a resolution high enough to compeat with a good scanner.

Gamerprinter
03-08-2010, 05:56 PM
I may have posted something like a tutorial in one of my challenge threads, I believe.

Basically, I do this every week - I did it for this months's challenge and I'm doing that today in fact.

Place your drawing/photo/whatever you are scanning onto the scanner bed. Use the paper's straight edge and place it against the plastic top "window" around the scanning glass - use the paper's edge helps keep the original straight. Scan the area needed, then keeping the edge against the lip, slide the drawing left or right, make sure to have at least a half inch overlap on what you already scanned, then scan again. Continue this process untill one side of the piece is scanned. If you have to rotate and do the other edge/side the same way. If you need to scan the middle of a drawing - its much tougher. If the original is just a copy or other kind of throw away original, I fold the piece to create a straight edge and do the process described above. If working from an original you can't damage - do whatever you can think of to keep a consistent straight edge to work with...


Once all scanned - in Photoshop or whatever you are using, create a new blank image the size (or just a bit bigger than the final size you need (make sure its the same resolution as the scans. Open your scanned files and cut an dpaste them into place. Even with all the attempts to keep it straight there's still a chance for somethign crooked, then you are forced to use the rotate function to get what you need... Got it?

GP

Redrobes
03-08-2010, 06:12 PM
This can work really well if you have a good scanner. Try that with mine tho and it would never work. If a crease lifts off of the glass then it goes black and also my platter is not very constant and tends to drift in the scan direction. Still, all said and done it would be the first thing to try if I had to do it. Doing the same with a camera sounds easier but I have found it more difficult to get the lighting even over multiple pages. If you can do it with one shot photo then you can take a mid grey sheet of card at the same time and normalize the lighting to some degree which can help.

When stitching I have found that if I blend all the edges of all the internal scans then I can line it up easier but maybe that just works for me.

Microsoft used to have this download called ICE which was a free beta thing going. You might be able to find it still. It used to stitch lots of images together. I think they have dropped it now tho - not sure - but I am told that you can now use photosynth and silverlight to do it. No idea what that entails tho. Theres other free image stitchers about tho but if your lining up flatbed scanned stuff from a good scanner its pointless. If doing that with photos then it might be more helpful.

Gamerprinter
03-08-2010, 06:21 PM
As always the job is only as good as the tool you're using. I have a $900 12 x 18 flatbed scanner capable of 9600 dpi non-interpolated - so yeah, I have a good scanner (I run a graphics shop, so I need good tools.)

GP

psyekl
03-08-2010, 07:10 PM
As always the job is only as good as the tool you're using. I have a $900 12 x 18 flatbed scanner capable of 9600 dpi non-interpolated - so yeah, I have a good scanner (I run a graphics shop, so I need good tools.)

GP

:!: Where did you find a scanner that good for only $900?! The largest scanner I could find goes up to 12.2 x 17.2 at 2400x4800 dpi but it cost CONSIDERABLY more than that!

Thanks for the tips so far! Keep 'em coming if you know of a good way to splice drawings.

Gamerprinter
03-08-2010, 07:23 PM
Well I used to use Photoshop to do the splicing, but that takes too long, if the scans aren't perfectly straight. My software app of choice is Xara Xtreme Pro 4.0 - which is a vector app, but I use it for all my mapping. Actually its easier to rotate your scanned image in a vector app, then in Photoshop or similair. Once the file sits on your screen in Xara, I just select it, click it again and rotation arrows show up at the corners, allowing me to freely rotate any direction at any increment. I rotate until it perfectly lines with the adjacent scanned image.

I zoom in lots to see details up close. Also sometimes I make my next scanned image 50% transparent so I can line up the overlap area over the adjacent image allowing me to line it up perfectly with necessary rotations. Make sure to remove the transparency before combining the images.

Since I do all my compositing in Xara, I don't need to do anything else, but if I plan to use PS or GIMP, I select the multiple scans placed correctly together, select the whole thing, then I export as a TIFF or JPG, then import to my image editor - that's it.

GP

RobA
03-08-2010, 08:56 PM
I'll repeat what SG said.. Give Hugin (http://hugin.sourceforge.net/)a try. It works very well.
Here is a tutorial for stitching scanned images.
(http://hugin.sourceforge.net/tutorials/scans/en.shtml)
-Rob A>

Midgardsormr
03-08-2010, 09:02 PM
The trouble I have with scanning large documents is the "lip" around the scanner's perimeter. If you can remove the lid and bezel, you can get the map to lay much flatter, eliminating the lift at the edges and allowing you to scan the center of the page easily.

Make each scan with a little bit of overlap, then move them all into a single Photoshop document. Select all of the layers, go to edit > Auto Align layers... Experiment with the different projections to get one that works. Usually collage or reposition work well for me.

TheHoarseWhisperer
03-01-2014, 06:32 PM
Howdy people. I thought I'd resurrect this thread to see if there are any new methods or tools for scanning large images. I'm currently hand-drawing a lite challenge map on an A3 page (297x420mm; 11.7x16.5"), and don't have a large enough scanner. So, does anyone know if the art of scanning large pages has moved on since 2010?

THW