Dirk Ahlers

Granularity as aQualitative Concept for GIR

NTNU – Norwegian University of Science and TechnologyTrondheim, Norway

Motivation· Growing positional accuracy brings (new)

challenges· Thinking in coordinates plus further

conceptualizations· Most entities are not really a point· Coordinates lack a description of size, etc.· Distinguish Locations, Location

References, and Entities

Annotating coordinates· What is 63°25‘10“N 10°24‘9“E?· Approach: Granularity as Level of

detail· Use numerical accuracy· Use conceptual hierarchy

· Increased model complexity (polygons, building models, …) may solve some issues, but is not fully available

Granularity example

NTNU63°25‘10“N 10°24‘09“E

Trondheim63.2°N 10.2°Ø

IT-Bygget63°25‘0.2“N 10°24‘9.9“E

Granularity Levels

City10km

No.10m

Street1km

zip5km

Region100km

Country500km

Door1m… …… … … …

Example of a named granularity hierarchy

Wikipedia Examples{{coord|63|25|10|N|10|24|9|E|type:edu|display=title}}latd = 63 | latm = 25 | lats = 47 | longd = 10 | longm = 23 | longs = 36{{Coord|61|N|8|E|type:country_region:NO|display=title}}{{koord|64|N|12|E|type:country_region:NO|vis=tittel}}{{coord|62.1210|7.1290|region:NO_type:waterbody|display =inline,title}}

Related concepts· Accuracy and Precision· Level of detail· Spatial resolution, conceptual/semantic resolution· Uncertainty of measurements, Propagation of

uncertainty· 14.08333, -87.18333 N → 14◦05’00” W 87◦11’00”

· Significance, significant figures, false precision, overprecision, tolerance, margin of error

· Estimation/approximation of the real world

Using Altitude· Granularity ≈ magnitude of

accuracy· → not just 2D, GIR can also consider

3D· On a large scale, the world is

relatively flat (largest elevation <+9km; >-11km)

· But on a local scale, height is interesting

Elevated structures

[Search and Navigation in Complex Overlapping Urban Spaces]

[http://trondheim2030.no/2015/11/09/ny-tredimensjonal-modell-av-trondheim-gjor-det-enklere-a-planlegge-framtidas-by/]

Conclusion· Thinking about location with

different semantic layers and concepts

· Granularity as a simple conceptual solution

· Better interpretation of coordinates by their referenced places

Contact

search://Dirk Ahlersgeo: 63°25‘10“N 10°24‘9“E @dirkahlersdirk.ahlers@idi.ntnu.no