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Solving road intersections in Illustrator

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#1
Hans van der Maarel

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Hoping to get a worthwile discussion on this topic:

Posted Image

The problem: 2 roads, of different classes, intersect. The lower class road is displayed on top of the higher class road, which looks odd and is not something you'd want to see on a map.

Changing the order of display so that higher class roads always get the highest priority often solves this, but not always. There are cases where it's visually a better idea to give the low class road priority.

So in order to solve these cases, a certain amount of manual work is needed. What I usually do in Illustrator is this:
- zoom in on the problem area
- get the scissors tool and cut the lower class road(s) close to the intersection
- select the ends and move them to the background

With this result:
Posted Image

Moving an entire road to the background is something I'm a bit weary of, as it might affect other intersections.

As you can see, this takes some time to do and gets really annoying if you have to do this for an entire map. Also, it's a non-automated process, which means I'd have to do it again for the next map update. Finally, it ruins the MAPublisher attributes (I work a lot with MAPublisher, so this does bother me).

Are there any alternative approaches, ideas or comments?
Hans van der Maarel - Cartotalk Editor
Red Geographics
Email: hans@redgeographics.com / Twitter: @redgeographics

#2
Nick Springer

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That does seem a bit tedious and manual as you mentioned. I usually just put the lower classed road layer below the higher classed road.

The only other thing I have done to solve this issue is for really wide roads where end cap shapes become a problem, I use "Outline stroke..." to create polygons out of the lines. You can then use the Pathfinder features to clip the polygons where necessary.

Typically you can do this for a whole layer at a time, so it's less manual labor, but your stuck if you want to change the width of the roads later. It also become difficult to change the shape of a road. I'm sure you would lose you MapPublishe attributes as well.

As a safety measure I often keep the original lines on a hidden layer so if I need to change something I can edit the line and then quickly convert to a polygon and trim it again.

Nick Springer

Director of Design and Web Applications: ALK Technologies Inc.
Owner: Springer Cartographics LLC


#3
ELeFevre

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Another manual version might be to create a new selection where the roads intersect and recolor the selection. In the example you provided, you could create a small selection box over the ends of the white lines and fill this selection with the yellow color of the higher class roads. It would create the same effect in fewer steps, so it seems. Plus, all of the selections would be on their own layer, so you would not have to cut up your work layers. Maybe, maybe not?



#4
ELeFevre

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On second thought, the suggestion I made would probably have to be done in an image editing program with more selection tools, rather than AI.



#5
Hans van der Maarel

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I have to admit I was a bit wondering about that. But the general idea is somewhat useful. Instead of cutting up existing lines and trying to move them to the background, once could simply make a new layer and place a little line there, covering the problem. The tricky bit would be to make sure it'd line up perfectly, so in the long run I don't think it'd be much of an improvement in terms of speed.
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Red Geographics
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#6
Jeff

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The tricky bit would be to make sure it'd line up perfectly, so in the long run I don't think it'd be much of an improvement in terms of speed.

Just copy the whole line, do a "paste in front", move it to a separate layer (or do it in one step by option-dragging the line to a different layer), and then trim it back to cover just the problem area(s). You might need multiple layers depending on the compexity, but there's no worries about whether they're lined up perfectly, and the original line(s) are left intact.

That trick kept me sane while creating nasty, interwoven highway interchange ramps. Use the same method to create any road/bridge casings.

#7
Rick Dey

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Hans,

I've got to admit that the first method you mention is pretty much what we've used around here, but then we don't reimport the linework for the next update, we reuse the exixting AI file. We will try to use layers as much as possible but that doesn't help to much when threading through interchanges.

Pasting in front (or Back) when creating the bridge casings is the only way to go. Increase the stroke, convert to outline, them trim down the bridge ticks as needed.
Rick Dey




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