How do I scan A3 paper with an A4 scanner?

[MapMappingMapped]

I'm nearing the completion of my largest maps linework, larger than previous works not only in size but in detail, and I figured I needed to know how to scan it beforehand. Assuming that's possible, of course, which I've heard it is.
Knowing the guild is really helpful
EDIT: Scanning in two parts I believe...

[Mouse]

Hi MMM

You've already answered your own question. It's a bit fiddly, but it works. I did Road to Tiamis that way to import it into GIMP for colouring.

I would suggest, however, that you actually do it in 3 parts - both ends and the middle. Match up the ends, and if you have any contrast mismatch problems (ie if your lines are darker on one half than the other where they meet, you have the middle section to blend over the top of them both.

The hardest bit for me was the human error thing of managing to place the drawing square on the scanner glass. I kept seeming to get it tilted one way or the other by half a degree! Another good reason for doing a middle section scan to blend over the end halves.

[MapMappingMapped]

*sheepish grin*
Thank you Mouse. I will use your advice. But I do wonder about the stitching together itself... Do I need an exact measurement of my paper? It came in a pad so its a few millimeters smaller on the sides than A3...?

[Mouse]

Ummm... I'm not really understanding the problem.

I had to do mine with the top open because I didn't want to fold the paper just to be able to scan it, so where the paper ended there was blackness where there was nothing covering the scanner plate. That's also how I knew if each part was slightly skewed or not. It was the line by which I rotated each piece back to 'square' again before I even tried matching them with each other.

I then aligned the end pieces with each other using the drawing itself to achieve the match, then matched the centre piece with the rest.

When all three were aligned as closely as possible I used an absolutely huge soft round brush to erase both ends of the middle piece until it effectively blended over the join between the end pieces.

I hope that helps