OpenStreetMap - The Quality Issue

OpenStreetMap,[object Object],The Quality Issue,[object Object],Oliver O’Brien,[object Object]

Contents,[object Object],Quality & Completeness,[object Object],Sources of Data,[object Object],Scans of Imagery for Tracing,[object Object],Imports,[object Object],Studies, Tools and Methods,[object Object],Comparison,[object Object],Other Considerations,[object Object],OSM in the Real World,[object Object]

Quality & Completeness,[object Object],OpenStreetMap – a crowdsourced spatial database of the world.,[object Object],How good is the data compared with real life?,[object Object],Is everything important on the ground in the database? ,[object Object]

GPS Traces,[object Object],In the beginning (~2004),[object Object],Tracks from GPS receivers,[object Object],Consumer-grade handheld devices,[object Object],Prone to random and systematic error,[object Object],Particularly in urban areas (multipath),[object Object],Particularly if walking,[object Object],Walk both ways down street, take the “average”?,[object Object],In theory quality improves with multiple traces,[object Object],Metadata doesn’t include measured quality,[object Object],eCourier van GPS traces for London,[object Object]

Out-of-Copyright Map Tracing,[object Object],Crown Copyright expires after 50 years,[object Object],Not so useful for urban areas,[object Object],Great for rural areas – less likely to change ,[object Object],Old, low resolution map better than nothing,[object Object],Started with Richard Fairhurst’s collection in early 2006,[object Object],Quality dependent on scan resolution and quality of rectification,[object Object],Paper warps, especially over 50 years ,[object Object]

Out-of-Copyright Map Tracing,[object Object]

Yahoo Aerial Imagery Tracing,[object Object],Agreement in late 2006 that allowed tracing,[object Object],In the UK, some large urban areas covered,[object Object],Accuracy better than GPS but not as good as newer imagery sets (e.g. Google),[object Object],Phantom roads,[object Object],Hidden barriers,[object Object]

Yahoo Aerial Imagery Tracing,[object Object],Coverage of many countries,[object Object],Iraq: “The whole road and rail network of the Baghdad area has been mapped using the Yahoo! imagery. As have some parks, forested areas, etc.”,[object Object],Australia (Sydney): “Completion of the greater metropolitan railway network… several complex road interchanges not practical to map on the bike”,[object Object]

Yahoo Aerial Imagery Tracing,[object Object]

NaPTAN,[object Object],Public transport nodes,[object Object],Once-off copy of DtT database in 2009,[object Object],Most useful for “less glamorous” bus stops as railway station coverage was already complete in OpenStreetMap ,[object Object],Rich metadata,[object Object],Envisaged as two-way, OSM would fix poor locations and might be fed back,[object Object],Imported on a county-by-county basis,[object Object]

NaPTAN,[object Object],NOVAM-Viewer,[object Object],Bus stops,[object Object],For reconciling NaPTAN/OSM,[object Object],Graphical tool,[object Object],Manage manual verification of the locations and metadata,[object Object]

Walking Papers,[object Object],Designed for large scale POI addition,[object Object],The source is annotations to existing OpenStreetMap data so ultimately dependent on the other sources,[object Object],Specially rendered to print out and add Points of Interest to,[object Object],Automatic georeferencing for tracing,[object Object],If you want it,[object Object]

Walking Papers,[object Object]

Imports,[object Object],A common theme so far – tracing,[object Object],Inherently poor quality due to user error,[object Object],Tiger (U.S.),[object Object],AND (Netherlands),[object Object],OS Open Data,[object Object]

Tiger (U.S.),[object Object],From US Government,[object Object],Imported in late 2007 (data from 2005),[object Object],Data quality low but good coverage,[object Object],More difficult to create a community to fix rather than map,[object Object],Specialist tools: CloudMade has realised potential of a cleaned-up set and has created web tools to help,[object Object],[animation],[object Object]

AND (Netherlands),[object Object],July 2007,[object Object],Relatively straightforward as there was little existing OSM mapping for the Netherlands,[object Object],From a digital mapping data company with navigation and LBS products,[object Object],First “complete” country in OSM,[object Object],“15-20m” offsets in places between Yahoo aerial imagery and the AND data,[object Object]

OS OpenData (U.K.),[object Object],No bulk imports (c.f. Andy Robinson),[object Object],Community still debating,[object Object],UK coverage already too comprehensive,[object Object],Possible licensing concerns,[object Object],Building outlines possibly the biggest win,[object Object],Some test imports – automated feature detection from Street View rasters,[object Object],Isle of Sheppey,[object Object]

OS OpenData (U.K.),[object Object]

Summary of Data Sources (UK),[object Object]

Studies on Quality,[object Object],MukiHaklay (UCL CEGE),[object Object],“Haklay, M., 2010, How good is volunteered geographical information? A comparative study of OpenStreetMap and Ordnance Survey datasets” Environment and Planning B: Planning and Design 37(4) 682 – 703,[object Object],“on average within about 6 m of the position recorded by the OS, and with approximately 80% overlap of motorway objects between the two datasets”,[object Object],Analysis in 2008 (Meridian 2),[object Object]

Studies on Quality,[object Object],MukiHaklay and AamerAther,[object Object],Beyond good enough? Spatial Data Quality and OpenStreetMap data,[object Object],OSM vsMasterMap I.T.N., looking at road lengths,[object Object],“The analysis shows that when A-roads, B-roads and a motorway from ITN are compared to OSM data, the overlap can reach values that are over 95%. … OSM is of better quality than Meridian 2.”,[object Object],“Positional accuracy is satisfactory for many applications. Attribute accuracy is also satisfactory.”,[object Object],Spring 2009,[object Object]

Studies on Quality,[object Object],“Just how good is it?”,[object Object],As good as many consumer-grade online mapping websites,[object Object],Depends on the care and keenness of the “local champion”,[object Object]

Studies on Completeness,[object Object],MukiHaklay,[object Object],Completeness in volunteered geographical information – the evolution of OpenStreetMap coverage (2008-2009),[object Object],“OpenStreetMap already covers 65% of the area of England, although when details such as street names are taken into consideration, the coverage is closer to 25%. Significantly, this 25% of England’s area covers 45% of its population.” ,[object Object],Affluence bias,[object Object],Covers to October 2009,[object Object]

Studies on Completeness,[object Object],MukiHaklay: OSM vs Meridian 2 (red),[object Object],Left: Features only,[object Object],Right: With attributes,[object Object]

Studies on Completeness,[object Object],Peter Reed,[object Object],DfT highway length figures per county,[object Object],“Is it complete yet?” ,[object Object],Depends on what you need,[object Object],Depends on where you need it,[object Object],Improving!,[object Object]

Tools for Completeness,[object Object],ITO World OS Locator ,[object Object]

Tools for Completeness,[object Object],“Lonely Buses” tool – 20m buffer,[object Object]

Getting Completeness,[object Object],Mapping Parties,[object Object],May 2006: “Mapchester” ,[object Object],Chris Perkins, Andy Robinson,[object Object],January 2007: Central London,[object Object],Steve Chilton,[object Object],Richard Fairhurst,[object Object],May 2009: Milton Keynes ,[object Object],Me, Andy, Steve,[object Object],October 2009: Atlanta ,[object Object]

Getting Completeness,[object Object],Milton Keynes,[object Object],2 days,[object Object],25 people,[object Object],[animation],[object Object]

Getting Completeness,[object Object]

Getting Completeness,[object Object],London Mapping Marathon series,[object Object],One hour of mapping followed by pub,[object Object],2008: Streets,[object Object],2009: POIs,[object Object],2010: Building outlines,[object Object],Build and keep the community,[object Object],Crises,[object Object],January 2010: Haiti earthquake,[object Object],High quality aerial imagery,[object Object]

Comparison,[object Object],Quality vs Google Maps,[object Object],POIs,[object Object],(Over)simplification of roads,[object Object],Completeness vs Google Maps ,[object Object],POIs again,[object Object],Databases vscrowdsourcing,[object Object],Coverage… ,[object Object],A few surprises – Pyongyang in OSM,[object Object]

Forbidden City in Beijing,[object Object]

Other Considerations,[object Object]

It Started Life as a Street Map,[object Object],It’s not Ordnance Survey MasterMap,[object Object],Roads are line features, not areal,[object Object],Not yet, anyway,[object Object],OpenStreetMap is just a database,[object Object],Anything can go in it…,[object Object]

Individual Trees in Bern!,[object Object]

Loose Taxonomy,[object Object],Need to consider the metadata too – is it on the map, is it in the right place, is it tagged appropriately?,[object Object],Community proposes and documents on wiki but doesn’t enforce,[object Object],Worldwide considerations,[object Object],Metadata sometimes present for source, always present for input/update date & user,[object Object]

Loose Taxonomy,[object Object],Partial order ensured by Steve Chilton’s OSM Mapnikstylesheet,[object Object],If you want to see your data appear on the map that “most” people see, follow the guidelines,[object Object]

Curves,[object Object],...or lack of...,[object Object],Ability to tag ways as curved,[object Object],Still straight lines in DB ,[object Object]

OSM in the Real World,[object Object]

CycleStreets,[object Object], “We'll be launching a page for Local Authorities v. soon about embedded versions of the CycleStreets planner on their sites”,[object Object], - CycleStreets,[object Object]

Skobbler,[object Object],Commercial Sat-Nav application based on OSM data with custom additions,[object Object],Motorway lanes for junction approaches,[object Object],Completeness crucial,[object Object],Display Google Maps on website for address finding (Google Local) but use OSM for routing and app 3D view,[object Object],Accuracy not so important,[object Object]

Skobbler,[object Object],Started in Germany,[object Object],The map is more complete,[object Object],Just launched in U.K.,[object Object],The map is probably good enough, though missing a lot of turn restrictions,[object Object],Users report bugs,[object Object],Skobbler fix remotely or highlight to OSM,[object Object],Both communities benefit,[object Object]

Flickr,[object Object],Beijing Olympics in 2008,[object Object],Flickr is owned by Yahoo,[object Object]

Waze in Chile ,[object Object],Recent accidental unattributed inclusion of OSM data from “unreliable source”,[object Object],Fine with attribution,[object Object]

Background for Visualisation ,[object Object],http://oobrien.com/vis/bikes/ (London),[object Object],http://osm.mapki.com/bikes/ (Minneapolis) ,[object Object]

Attribution,[object Object],Various – Imagery of OpenStreetMap data which are CC-By-SA OpenStreetMap and contributors.,[object Object],Various – Imagery of Ordnance Survey OpenData Street View rasterswhich are Crown Copyright and Database Right 2010.,[object Object],p4 – Photograph of GPS unit by Steve Coast.,[object Object],p9 – Imagery of out-of-copyright map by Richard Fairhurst,[object Object],p16 – Photograph of Walking Papers in pub by Harry Wood.,[object Object],p27 – Maps produced by MukiHaklay.,[object Object],p28 – Map produced by Peter Reed.,[object Object],p42 –Screenshot of motorway junctions in OSM by Barry Crabtree.,[object Object],p43 – Photograph of ambulance by DBH NHS media services.,[object Object],p50 –Photograph of Boris Bike by Pocket Lint website.,[object Object],Other imagery may be copyright of the producers referred to on the same page.,[object Object]

More,[object Object],http://www.oliverobrien.co.uk/,[object Object],My research blog,[object Object],@oobr on Twitter,[object Object],o.obrien@ucl.ac.uk,[object Object]

OpenStreetMap - The Quality Issue

OpenStreetMap - The Quality Issue

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