Contour Lines

[Dean]

I want to make a topo map, with contour lines. Going for Swiss shaded style. The problem I'm having is with the contour lines. I've read Ascension's tutorial and tried out the techniques, and while the maps it produces are pretty, I'm not satisfied with the contour lines. I've tried various combinations of Cutout, Posturize, Find Edges, and Trace Contour. It looks OK, but not great. So, I think I'm gonna have to hand draw them.

Any suggestions you could offer about this huge undertaking? What would be the best way to draw these contour lines? I'm thinking just draw them up as paths, and then "Stroke Path" onto a layer in my map. Any better ways? I'm going to start small-scale, for the first map at least.

For what it's worth, I think the main reason the quick and easy filters aren't working so well for me is because I'm working at 300 dpi. I want to print the map when I'm finished. A4 sized canvas, CMYK.

[Ascension]

The way I would tackle hand-making your own contour lines would be to just lay down color blobs, lowest areas in black then proceed up through the grays each on its own layer say in increments of 10, set those layers to zero fill and then put a layer style of stroke on it. That way you can get complete control of where your lines will be. It might take a while and lots of trial and effort to get them right but it gives you complete control.

[Dean]

The way I would tackle hand-making your own contour lines would be to just lay down color blobs, lowest areas in black then proceed up through the grays each on its own layer say in increments of 10, set those layers to zero fill and then put a layer style of stroke on it. That way you can get complete control of where your lines will be. It might take a while and lots of trial and effort to get them right but it gives you complete control.

Hmmm, sounds like a good technique. I should also say, however, that I want the contour lines to be overlaid on a shaded relief map. Would the "coloured blob layers" technique work best before or after doing the actual shaded relief?

I think the best way to achieve what Ascension is talking about would be to make a custom action that automatically generates a low opacity layer UNDER the layer you're working on. That way I could overlay all the contour layers on top of the shaded relief layer, painting them up in real time. Have I got that right?

[tilt]

you can also change the color of the contour layers to white when you are done and set the layer to darken - that way only the contour will remain. Hmmmm... but that will give a job of fixing layers crossing each other where they shouldn't ... but depending on what you want - this could help

[Redrobes]

Assuming that you don't have a 3D DEM / model of the terrain, the way I do contour lines is to draw lines on top of the map in a new layer. You can do that with a tablet or by printing it and then using a pen and then scanning it. Once you have thin lines then up the contrast so that they are 2 colour black and white only. Then alternately flood fill in odd ones in black so as to leave a zebra striped set of contours. At this stage you can blur / sharpen to round of corners or up res the map to the final size. Then ensure that its got full contrast black and white again (two colour only) do a find edges on it and this will produce 1 pixel thin contour lines. From there you can thicken them or anti-alias them as required. Put these on a layer above the one your drawing the shaded relief using the dodge/burn or by using multiply mode and the underneath will show through.

[Dean]

Thanks everybody. I took all of the advice into consideration and ran some tests this evening. Looks pretty promising, although there are a few creases to smooth out yet. I liked the technique Ascension suggested the best. Only problem was that the strokes ended up overlapping all over the place. I had to paint every contour layer to the edge of the canvas to eliminate the problem (or fill the canvas, then erase to paint in the contours). Didn't want to fill them all with white, as I wanted to keep the different contours filled with distinct colors. Anyway, this technique seems to work well, but I think it'd be easier to draw the contours lines by hand for a bigger map with lots of mountains. Or maybe it'd work better to paint from the highest elevations down? Hmmm, will try that.

I also found it much easier to do the relief shading after the contour lines were in place, so I might have to rethink the order of the workflow. I'll try some more tomorrow and see if I can figure it out better. Too late now.