Monday, September 24, 2018

Grasslands (Part 5)

So far I completed the little “tuft of grass" marking and implemented at least a rudimentary display on the map.  Part of the challenge in using the tuft of grass mark on the map is that it's fairly intrusive if used widely.  It looks much better in a small area of the map.  So I'd like to try creating a new grasslands marking that might be more subtle.

An example of the kind of effect I'd like to achieve can be seen on this map of Middle Earth by Misty Bee:
This is quite a lovely map, so it's easy to overlook the faint horizontal dotted lines that fill the empty spaces.  They add interest to the empty space without distracting from the other map elements.

Here's another example, from a map of Romania by Cartographer's Guild user Kasey:
I'm not exactly sure what the small square bumps on the lines are supposed to indicate, but once again you see the faint line motif to indicate open land.

Drawing a horizontal line is pretty straightforward, so I can start with just drawing lines where I would have drawn the grass symbols:
One drawback of using the computer display is that you can't drawn infinitely thin lines -- in the end a single pixel is the limit of your resolution.  So it's impossible for me to get lines as thin as those on (say) the Romania map above.  That aside, these lines could probably use a little variation so they're all not perfectly horizontal, and probably be spread out more as well.
Here I've also turned off the grass coloring and spread out the grass symbols to cover all the land area.  This isn't awful but doesn't add much either.  Let me try the dotted line version and see how that looks.

For dotted borders I use SVG dash arrays.  Dash arrays are very flexible, but can only be applied to a path, so if I use this I'll be limited to a single width, color, etc., at least within one line.  Still it should be fairly quick to implement and see if it has any potential.  Here's a simple first effort:
The lines in the Middle Earth map above are more closely spaced, faded and varied, so let me try to add (some) of that.
This is not too bad.  It would probably benefit from some “hand-drawn" embellishments like jitter, but I'm not sure I'll use this enough to warrant the effort.  If I find that I'm using it a lot I'll go back and work on it some more.

Here's a variant where instead of making regular dotted lines, I'll make the dashes get bigger in the middle and smaller near the ends:
Visually it doesn't look a lot different.

In the meantime, let's see how it looks with the isolated grasslands style:
That's not terrible.  Here's the same style but with the lines more thickly placed:
This seems acceptable.

It's also interesting to combine the two styles, so that you have lines for the low grass and hachures for the deep grass:

That about wraps up illustrating grasslands (at least for now).  My general conclusions are that grassland markings work best when they are limited and/or use a subtle indicator.  However, there's a danger that marking only some grasslands implies that other areas are deserts, particularly for maps that use a brown color for land.  Distinguishing “deep grasslands" from “prairie" adds interest to the map (at least in my opinion).

Next time I'll look at modifying the grass symbol to create a symbol for marking swamps.


6 comments:

  1. As a note, of your uploaded images, Image13 and Image15 both read as desert to me, due to how sparse the lines were. Once you did more densely packed lines in Image17, then it read as grassland. The next image (Image3) looked like grasslands surrounding desert (the areas with no lines).

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  2. That makes sense. So maybe density helps distinguish grasslands from desert.

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  3. In my mind, the tufts of grass with the green background more suggests swampland or marshland rather than grassland. But maybe that's just me.

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  4. >I'm not exactly sure what the small square bumps on the lines are supposed to indicate, but once again you see the faint line motif to indicate open land.

    All the available data indicates that we are dealing with small rural houses—probably farms that are exploiting the vast agricultural resources of the region—and maybe some workshops. ;)

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  5. >One drawback of using the computer display is that you can't drawn infinitely thin lines -- in the end a single pixel is the limit of your resolution. So it's impossible for me to get lines as thin as those on (say) the Romania map above.

    This is a puzzling statement, and a glaring limitation of SVG too.

    A thin line might described by a 1px-line, but when I need thinner width (less than 1px) the common algorithm that comes to mind is Gupta-Sproull, which is not that common due to computation time. (The idea of drawing lines—probably with Bresenham's line algorithm—and then blurring is more computationally expensive and weights are not normalised, which gives feeling of thicker lines.)

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    1. To be clear, I was talking about the resolution of the display. SVG will let you draw thinner lines, and (depending upon the browser/display engine) will make some attempt to render those lines. But in the end you are limited by the display resolution.

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