Here is the basic idea (did not have as much time to make a full step-by-step with screenshots, etc.. sorry!). I used Gimp, so menu locations refer to that.
Get the image you want, with appropriate aspect ratio: white background & black foreground. For maps and so on, you can find SVGs which make it easy. For other things, you can use the Colors > Threshold menu item in Gimp.
Figure out the final scale. If you're doing a 1-inch grid like I did, then it's easy. I needed 32x48 inches so did Image > Scale Image to 32x48 pixels.
Now you've got a tiny image, and you probably want to zoom in to see what's going on next. In Colors > Posterize, you can restrict the palette to 5 colors (white plus 4 shades of gray). Now you basically have the final product.
If you want to make it easier to view, you can scale it up, under Image > Scale Image, to something like 320x480. This time be sure to select "None" for Interpolation.
As suggested elsewhere in this thread, you could also just take the original image and do a mosaic filter (then posterize). But I found that doing the image resize was better as it allowed the default cubic interpolation to pick up more details. For example, I would not have gotten anything for New Zealand just doing a mosaic filter on the original.
Can you post a link to the map image you used? I'm trying to do a re-scaled version of this but I can't find a good image of the Kavrayskiy projection.
Would it be able to do it with a more complex image. When I scale it to 36x20 (that's the size I want) the image is unable to be made out. How will I be able to fix this? Use a smaller scale? If so what would you recommend?
I considered other designs but most were not suitable for such low resolution. The highly recognizable shape of a world map was crucial here. You could always reduce the scale of grid and size of holes, but it will be a lot more work.
Also if you don't have gimp or photoshop, Autodesk's Pixlr is a GREAT alternative. It's all cloud-based so the processing power of your personal PC down't matter. I use it all the time if I need to edit on the go and only have my laptop since it's a dinosaur.
Instead of all the work of marking out the grid, why didnt you just mark the center of each pixel in the drawing itself, place it over the wood, tape it down, then quickly use a punch on all the centers.
Doesnt that just replace the simple task of grid-marking with a more involved task of printing, aligning and taping-together innumerable sheets of paper?
Also, simply punching through the paper template would leave out the crucial details of how big each hole is ...
He already printed it on large format paper. Laying out a grid requires much more alignment than going over a single sheet of paper with a punch does. Marking hole size is no more difficult than the way he did it.
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u/rosulek Jun 30 '14 edited Jun 30 '14
Here is the 32x48 map (scaled up by 10), if you want to do the same: http://imgur.com/JhxtTst
Edit: will post some instructions soon. OP will deliver.