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Analyzing changes in OSM over time

�full history access to OSM data through the ohsome framework

Workshop @ SotM 2022 Firenze�2022-08-21

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What you can learn today:

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How to analyze changes in OSM over time:

Investigate tag usage by filtering OSM data

Count OSM features for a given region

How to derive information about OSM quality

Estimate completeness of OSM features

Describe how up-to-date OSM features are

How to embed public APIs in your analysis workflow

Send a request to the ohsome API

Send a request to the OQT API

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Intro - ohsome Dashboard ohsomeHEX &

User friendly Access to OSM History and how to analyze changes over time

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https://ohsome.org/apps/dashboard

https://hex.ohsome.org

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https://ohsome.org/apps/dashboard

https://hex.ohsome.org

live global �user defined queries

precomputed global timeseries

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https://hex.ohsome.org

What are precomputed global timeseries?

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Topic (e.g.Number of Hospitals)

aggregated (e.g. count)

and grouped into a global hexagonal grid

in multiple spatial resolutions

on a temporal resolution (e.g. monthly)

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precomputed global timeseries

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[WIP]Quality Indicators integrated from

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https://hex.ohsome.org

precomputed global timeseries

Integrations

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ohsome API full history data extraction

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OQT API - ohsome Quality Analyst

(Saturation Indicator)

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https://ohsome.org/apps/dashboard

live global �user defined queries

What is a user defined query?

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Filter by tags, OSMType or GeomType

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Simple aggregations of OSM Objects

(sums of count, length, area, perimeter)

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optional: grouping (to compare things)

(split results by OSMType, boundary, tag, key)

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flexible temporal range and resolution

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First Exercise - Changes in OSM over time

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Use the ohsome Dashboard

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Time: 10 Minutes

How detailed are objects mapped? Compare Hospitals grouped by OSM- Types in Tanzania

Which tags are accepted by the community in Italy? Compare forests tags grouped by keys

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How does my mapping campaign progress? Count buildings in HOT Task #2825

filter:

amenity=hospital or

healthcare=hospital

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filter:

( natural=wood or

landuse=forest or

landcover=trees )

and geometry:polygon

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groupByKeys:

natural,landuse,landcover

filter:

building=*

and geometry:polygon

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https://tasks.hotosm.org/projects/12825

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  • Examples

Compare OSM-Types over time - Geometric complexity of Hospitals

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  • Examples

Compare tags grouped by keys - Acceptance of forest tags

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  • Examples

Link to HOT Tasking Manager

https://tasks.hotosm.org/projects/12825

(accessed 2022-08-05)

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  • Examples

Count objects - Progress of a HOT mapping campaign (daily)

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Intro - ohsome quali al(OQT)

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from temporal evolution (OSM History) to OSM Data Quality

  • how up-to-date is OSM?
  • how complete is OSM?

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  • Compute and provide quality estimations of OpenStreetMap data

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  • OQT calls those quality estimations Indicators

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  • Indicators are computed for a specific area (`bpolys`)

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  • Indicators are computed for a certain set of aggregated OSM features (`layer`)

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oqt.ohsome.org

https://oqt.ohsome.org/api/docs

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APIs of the ohsome ecosystem

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Use the APIs - Exercises

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Exercise 1 - ohsome API Aggregation:

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Get the temporal evolution for healthcare facilities

Exercise 2 - ohsome API Data Extraction:

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Extract OSM features representing schools over time

Exercise 3 - OQT �API Data Quality:

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Estimate completeness and currentness of XXX

Time: 10 Minutes

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Use the APIs - Exercises

https://gitlab.gistools.geog.uni-heidelberg.de/trainings/sotm-2022-workshop

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Questions & Answers

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Contact

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Benjamin Herfort

Benjamin.Herfort@heigit.org

Rafael Troilo

Rafael.Troilo@heigit.org

Michael Auer

Michael.Auer@heigit.org

Matthias Schaub

Matthias.Schaub@heigit.org

https://heigit.org/

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ohsome Technology Stack

ohsome API

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ohsomeHeX

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ohsome quality analyst

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