"rainbow lines" for overlapping polylines - leaflet plugin

[Aaron Antrim]

Hello Transit Developers!

You may be familiar with this problem.  Showing overlapping transit routes in "slippy maps" cover each other, and it is hard to see all the routes and a full view of the system.

I have looked for some leaflet plugins to solve this problem, but I do not think they exist yet.  The best option, I think, would be a leaflet plugin that automatically offsets overlapping polylines to show classic transit "rainbow lines" (BART map example, https://www.bart.gov/stations).

Have I overlooked any resources?

Would anyone be interested in collaborating on or co-funding the development of an open source "rainbow lines" plugin for leaflet?

-Aaron

-- 
Aaron Antrim
www.trilliumtransit.com
Portland, Oregon
503.567.8422

[Richard Kendall Wolf]

On Apr 10, 2014, at 2:53 PM, Aaron Antrim <aa...@trilliumtransit.com> wrote:
>
> Hello Transit Developers!
>
> You may be familiar with this problem. Showing overlapping transit routes in "slippy maps" cover each other, and it is hard to see all the routes and a full view of the system.

Aaron,

I do not know if this is helpful at all, but you reminded me of a question I once asked the MapKit folks when I was at Apple's WWDC (I lost the lottery this year ... 19 consecutive WWDCs, this year would have been my 20th anniversary).

Anywho, I said that I was drawing a polyline on a map view from GTFS data, but wanted to know what the best way would be to offset that polyline, given that transit lines often overlap (Chicago Loop, in my case). I was especially concerned because of the way Apple rescales map views when a user zooms in/out of a view (I couldn't, say, fudge the latitudes and longitudes of the polylines to offset them because that won't scale).

The clever answer I got from Apple was to apply an affine transform to the drawing layer as I was in the process of drawing the polyline. That way, when a user zooms in/out, the polylines remain offset a number of points from one another in a consistent way. Dunno if you can do the same thing ... but I thought I'd throw it out there. :)

[Andrew Byrd]

On 04/10/2014 09:53 PM, Aaron Antrim wrote:
> I have looked for some leaflet plugins to solve this problem, but I do
> not think they exist yet. The best option, I think, would be a
> leaflet plugin that automatically offsets overlapping polylines to
> show classic transit "rainbow lines" (BART map
> example, https://www.bart.gov/stations).
>
> Have I overlooked any resources?

Hi Aaron. Conveyal is working on a library that is in many ways similar
to what you want. Check out https://github.com/conveyal/transitive.js .
It's intended to find a compromise between geographically accurate and
schematic transit maps. David Emory should be able to provide further
information if you're interested.

-Andrew

[Sean Barbeau]

Good article discussing Conveyal's Transitive.js project is on the Mobility Lab site:
http://mobilitylab.org/2014/04/16/the-technology-behind-a-new-kind-of-travel-planning/