[OSM-talk] Potlatch 2

[Richard Fairhurst]

Hi all,

I’d like to tell you about Potlatch 2, the all-new version of the 
OpenStreetMap online editor.

Potlatch 2 is a complete rewrite still with the same principle in mind: 
an editor which hits the right balance between speed, ease-of-use, and 
flexibility. It’s under very active development at the moment and I’ll 
include a link at the end of this mail where you can have a look.

But there are four big new features - and one behind-the-scenes change - 
to tell you about first.


== New feature - friendly tagging system ==

Potlatch 2 has a friendly, intuitive tagging system. The mapper can use 
graphical menus, dedicated fields, and icons to get the tagging just 
right - without the need to remember tag names and values.

For example, you can choose highway types from a set of icons, then add 
a speed limit by selecting the appropriate restriction sign.

All this is fully customisable using a straightforward presets file. 
Using this, you can create your own favourite tag combinations.


== New feature - WYSIWYG rendering ==

Potlatch 2 has an all-new rendering engine far in advance of the current 
one.

With road names, patterned fills, rotated icons, and much more, the 
editing experience can be like working live on the familiar Mapnik 
rendering, the cyclemap, Osmarender, or anything you like - making it 
much more approachable for the beginner.

Just like the tagging, the rendering is easy to customise. It uses a 
special form of CSS, called MapCSS, which lets you create 
wonderful-looking maps with just a few lines of text. The tagging and 
rendering together make Potlatch 2 ideal for ‘vertical’ mapping 
applications, such as a cycle-specific editor or a building/addressing 
editor. Stylesheets aren’t just about making the map look pretty: you 
can create stylesheets to help your mapping, such as one that highlights 
roads without names.

The rendering engine (Halcyon) is available as a compact (<100k) 
standalone component which you can embed in webpages, so your custom 
maps can be used outside Potlatch 2.


== New feature - Beginners’ Guide ==

You couldn’t write instructions for Potlatch without writing 
instructions for OSM. The new Potlatch user needs to know about tagging, 
surveying, and copyright - but they’re certainly not Potlatch-specific.

So Potlatch 2 will have an accompanying ‘OSM Guide’, explaining the 
basics with friendly, illustrated text. It will be concise, focused and 
clear.


== New feature - vector background layer ==

Mappers are working more and more with imports. But the approach until 
now has been to import data directly into the map - and many people have 
pointed out the problems this can lead to.

Potlatch 2 will support vector background layers. You can load 
OSM-formatted data from servers or files, and work on bringing it into 
the map the way you want, at your own pace.

Because this integrates fully with MapCSS stylesheets, you can choose to 
temporarily hide background data, or show (say) only footpaths... 
whatever you like.


== Fully rewritten in ActionScript 3 ==

Potlatch 2 is written in ActionScript 3, a Java-like language with an 
open source compiler and full docs available online. The Potlatch 2 
source comes with instructions on getting started and is, of course, 
permissively licensed under the WTFPL.

Potlatch 2 thus far has been written by Dave Stubbs and myself. But we 
would love to see more people hacking on the source. There’s a 
potlatch-dev mailing list especially for this 
(http://lists.openstreetmap.org/listinfo/potlatch-dev ).


== Playing with Potlatch ==

So where are we up to right now, and how long do you have to wait?

The tagging system, rendering engine, geometry editing, and server 
communication are all up and running - the core of the editor, and the 
real hard work.

Some other features, like Yahoo and tiled backgrounds, are finished but 
not currently exposed through the editor: they’ll be along shortly. 
Others, such as GPS track support, the Beginners’ Guide and the vector 
background layer are not coded yet but are intended for the initial release.

Potlatch 1 has some three years of development behind it, of course, and 
much of this feature set has not yet been ported to Potlatch 2. There’ll 
be countless little UI tweaks (no keyboard shortcuts yet, for example!); 
and as you’d expect for an in-development version, performance can 
sometimes be sluggish and there’s a lot of optimisations we’d like to do.

But with work progressing so fast, this seemed a great time to talk 
about it. Both the tagging system and the renderer are enormously 
flexible and we’d like to see people hacking on them as soon as possible.

So have a play, let us know what you think, and grab the source. You can 
find a read-only running version at:
	http://www.geowiki.com/potlatch2/

or play with the renderer alone at:
	http://www.geowiki.com/halcyon/

Should you want to try a particular area, just put the lat and lon in 
the URL like this:
	http://www.geowiki.com/potlatch2/?lat=52.2&lon=0.1
	http://www.geowiki.com/halcyon/?lat=52.2&lon=0.1

and the source is at:
	http://trac.openstreetmap.org/browser/applications/editors/potlatch2

and you can read MapCSS documentation at:
	http://wiki.openstreetmap.org/wiki/MapCSS

cheers
Richard