UserAndre Castro/maps01

Maps

As is possible to render retrieved data from osm api and then render that data into a static map in svg format, that started to resonate with the work we have been developing with Michael concerning svgs and a drew possibilities for different lines of action.

New Maps

Thinking about my fascination with maps, specially unconventional maps in which accuracy and compreenshion are not priorities, such as map that friend draws you on a napkin, I started to image what this map could be, what form it could take, what would be its purpose, how it would be displayed and navigated.

Seeing in blog a map of South America in which a mistake prevented the map-lines from being printed. The fluidity and bordeless of the map said me something about mobility and loosening of geo-policital constraints.

I would be great to do a similar thing to a city. What happens when your only referrences are the street names? Does our vision of it changes? Can we still navigate through it? Will it still be possible to go from place A to place B taking this map as a reference?

This possibility also made sense with a simple idea I had been tinkering with of removing the stree name's suffixes. So in Rotterdam "Nieuwe Binnenweg" will become only "Nieuwe Binnen".

So I went on doing so.

retriving osm data

...

data manipulation

...

• [xml-manipulation-code]

data rendering to svg osmarender

osmararender renders osm data into an svg. It is constituted of 2 files... - ...features.xml - one is supposed to edit, to change the apperance of the map - osmarender - instructs on how the rendering should be done, and is advised not to chnage it.

I have started by altering the features file, so for example: I remove all the elements besides thes the street names, or live only the lines an street names

However when rendering the svg becomes filled with elements which are not present, therefore making it heavy and dificult to go through

Manipulating the Map

features file

• removing the '//area|//circle|//symbol|//caption'

* removing also line | wayMarker tags will produce words-maps

• changed svgBaseProfie="basic (tinny)

• background remove - in the svg the tag rect

<id="background" x="0px" y="0px" height="72.8048679813291px" width="128.000000000004px" class="map-background"/> if removed we take way the backgorund :)

• borderless

osmarender xsl file

Currently I am lookingon how to change to osmarander.xsl file so just the elements that are wanted are rendered into the svg. However muhc work needs to be donde here.

• parsing

x = lxml.etree.XSLT(doc) http://lxml.de/xpathxslt.html#xslt

• (To Do: simplify ways - these seem to be made of several layers of unecessary grey )

• To Do: remove background

==

The rule file is an xml file that specifies the drawing rules. Its basic structure is a list of selection rules containing rendering instructions that are processed sequentially

Each rule specifies what elements to select based on a matching key/value pair (for example, e="way" k="highway" v="motorway" will select all ways that have a highway tag with a value of motorway). It then specifies what to do with these nodes or segments or ways.

---

I have recently found open street maps. Not only it is a open-source project that allows users to search and find place, but also anyone to contribute for the improvement of the maps, and it allowing geographical data to be easily retrieved.

I would explore its potential to create non-functional maps or trajectories that could open new perspectives on the city space. (situationists echos)

Map Making using Open Street Map

• installed osmarender

ask for the geographical data

• find coordinates

In openstreetmap.org go to Export Menu and check the coordinates. they organized as [lat,long, lat++, long++] area[1,3,2,0] or in other works [lat,long, lat++, long++]

• wget that area's data

wget -O data.osm "http://api.openstreetmap.org/api/0.6/map?bbox=4.4552603823670465,51.91739525301985,4.46384345121436,51.920373035178464"

• XML data manipulation

render the data into an svg

• mv this data.osm file into the same the osmarender dir

• call osmarender to process the data.osm into a rendered svg image

• • osm-map-features-z17.xml tells what to put on the map - CAN BE EDITED in order to change the result
  • osmarender.xsl a stylesheet that directs the actual rendering work - DON'T MESS WITH IT!
  • xsltproc applies XSLT stylesheets to XML documents.

	
xsltproc osm-map-features-z17.xml > rendered-map.svg

tanttttaaaaaa! the map (svg exported to svg)

data filtering

osmfilter can also be used to include or exclude certain map data

• Info sources:

http://www.use-it.be/europe/docs/OSMmanual/

http://wiki.openstreetmap.org/wiki/Osmarender

Getting Data

Other Possibilities

• GPS traces
• Topographic map

OSM Elements

source: http://wiki.openstreetmap.org/wiki/Map_Features

maps are made up of a few simple elements (Data primitives): nodes, ways and relations. Each element may have an arbitrary number of properties (a.k.a. Tags) which are Key-Value pairs (e.g. highway=primary). (All editing interfaces use the elements and allow the input of tags. )

NODE - the basic element, building block. Nodes consist of latitude and longitude (Nodes are needed to define a way, but a node can also be a standalone unconnected point representing something or points of interest (POI). Standalone nodes should always have at least one Tag such as amenity=telephone). Example <node id="25496583" lat="51.5173639" lon="-0.140043" version="1" changeset="203496" user="80n" uid="1238" visible="true" timestamp="2007-01-28T11:40:26Z"><tag k="highway" v="traffic_signals"/> </node>

WAY - ordered interconnection of at least 2 or more nodes can describe a street, footpath, railway line, river, fence, power line, area or building outline. CLOSED WAY - the first and last nodes are identical, enclosing an AREA

Databases and data acess APIs

http://wiki.openstreetmap.org/wiki/Databases_and_data_access_APIs

API

The main API is the method of obtaining OSM data used by editors. Its limitations are that it will only return very small areas <0.25deg square.

This method of obtaining data should therefore be reserved for editing applications

XAPI - Retrieve Particular Data Request Needs to be edited

To acess data of a given area in http://www.openstreetmap.org/ go to Export Menu and check the coordinates. they organized as [bbox=lat,long, lat++, long++] area[1,3,2,0] or in other works [lat,long, lat++, long++]

EXAMPLES:

search all nodes in a small are in west Rotterdam:

wget http://open.mapquestapi.com/xapi/api/0.6/node[bbox=4.4552603823670465,51.91739525301985,4.46384345121436,51.920373035178464] -O rotterdam-west-test.osm

search pub nodes in Rotterdam

wget http://open.mapquestapi.com/xapi/api/0.6/node[amenity=pub][bbox=4.3142405612056836,51.87797066611181,4.588898764319719,51.973245376533505] -O rotterdam-pub-test.osm

search ways in a small area in west Rotterdam:

wget http://open.mapquestapi.com/xapi/api/0.6/way[bbox=4.4552603823670465,51.91739525301985,4.46384345121436,51.920373035178464] -O rotterdam-west-way-test.osm

Ways are where I can gather information about streets

Ways get rendered as streets/railways/footpaths/canals etc according to the tag(s) indicating what type of way it is. Ways are contiguous and non-branching. (You can get from beginning to end by following segments of the way, without "jumping" or backtracing)

eg: <tag k="addr:street" v="Mauritsstraat"/>

eg:

 <way id="5090250" visible="true" timestamp="2009-01-19T19:07:25Z" version="8" changeset="816806" user="Blumpsy" uid="64226">
   <nd ref="822403"/>
   <nd ref="21533912"/>
   <nd ref="821601"/>
   <nd ref="21533910"/>
   <nd ref="135791608"/>
   <nd ref="333725784"/>
   <nd ref="333725781"/>
   <nd ref="333725774"/>
   <nd ref="333725776"/>
   <nd ref="823771"/>
   <tag k="highway" v="unclassified"/>
   <tag k="name" v="Clipstone Street"/>
   <tag k="oneway" v="yes"/>
 </way>

All Elements

All elements (nodes, ways and relations) that match the given filter predicates can be requested using the following URL:

http://www.informationfreeway.org/api/0.6/*[...]

This returns an xml document containing nodes, ways and relations that match the search terms. For each matching way the nodes and referenced by that way are also returned. Likewise, for each matching relation the ways and nodes referenced by that relation are also returned.

Source: http://wiki.openstreetmap.org/wiki/Xapi

relevant links

http://derickrethans.nl/what-is-openstreetmap.html Good explanation of OSM project

http://weait.com/content/openstreetmap-planet-file

http://derickrethans.nl/spatial-indexes-data-sqlite.html

osm Frameworks

Deploying your own Slippy Map

Pyrender-map rendering framework, programmed in Python

Osmfilter

PythonOsmApi

Databases and data acess APIs

http://wiki.openstreetmap.org/wiki/Databases_and_data_access_APIs

xpath tutorials

http://infohost.nmt.edu/tcc/help/pubs/pylxml/web/index.html#intro

http://www.w3schools.com/xpath/default.asp

http://lxml.de/