[PPT] - Geoapplications development http://rgeo.wikience.org Higher School PowerPoint Presentation

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Geoapplications development http://rgeo.wikience.org

Higher School of Economics, Moscow, www.cs.hse.ru

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Agenda

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What is geospatial data?
How is it different from other types of data?
Examples of geospatial data
What is geoapplication?
Course goals & organization
Real-world examples: companies using geospatial data
Tentative projects to participate in
Main readings
Quiz
Practical lesson: 3D Globes

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Geospatial data: 2 types (simplified)

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VECTOR

What is raster data? http://help.arcgis.com/EN/arcgisdesktop/10.0/help/index.html#//009t00000002000000

RASTER matrix

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The main difference from other data types (simplified)

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RASTER matrix

A fundamental difference: the presence of spatial coordinates

each cell has (lat, lon, value)

(lat_i, lon_i) for each vertice

VECTOR

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Is that all?

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is there something strange here??

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Hint: areas…

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is Greenland larger than Africa??

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Let us consult an Encyclopedia or Wikipedia

2,175,600 km2 World size ranking: 14 30,370,000 km2 World size ranking: 2

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is Greenland larger than Africa??

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https://takeitscienceblog.wordpress.com/2016/08/31/how-big-is-your-country/ http://geoffboeing.com/2015/08/map-projections-that-lie/

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Distances

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Two airplanes are flying … Plane A: (60ᵒN, 40ᵒE) → (60ᵒN, 30ᵒE) Plane B: (40ᵒN, 40ᵒE) → (40ᵒN, 30ᵒE) 40ᵒ - 30ᵒ = 10ᵒ Both traveled the same distance?

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Everything is not so simple…

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To name a few: * distances between two points with the same longitudes are different for different latitudes

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A small caveat: circular/periodic axes

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longitude range is [ –180 … +180 ] but what if I want to move 10 degrees eastward from 179 degrees? 179 + 10 = 189 …. actually -171

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Lesson learned

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Areas, shapes, angles, distances depend on…

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Examples of geospatial data: vector

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Geo prefix

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→ → → → → →

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Examples of geospatial data: raster & vector

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More details are at: http://www.wikience.org/tropical-cyclones/wind-swaths/

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Examples of geospatial data: satellite raster

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Visualization examples

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Much more examples are at: http://goworldwind.org/demos/

Video on terrain Analytic Surface Airspaces Extruded Shapes Scankort Denmark Data We can do more together during course work

NASA World Wind engine

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Satellites, smartphones, GPS (1): basic theory: geographic coordinate systems, geocoding, vector and raster data types and operations (3): I/O with vector (SHP, KML, GeoJSON, WKT) and raster (GeoTIFF, NetCDF, HDF) formats (4): network protocols for geodata exchange: WCS, WFS, WMS, OPeNDAP (4): frameworks: Mina, Netty that is used by Twitter (3,4,5): spatial databases and servers: PostGIS, SciDB, GeoServer, TDS (5): software libraries for geodata processing: vector Java Topology Suite and raster ImageMagic, GDAL (6): visualizing geodata with NASA WorldWind, Mapbox, Leaflet, CartoDB

Course goals & organization

Topics cover technologies for a complete geospatial data management stack:

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Course assessment

Code Description Contribution, % LP Lecture presence 20 PP Work during practical lessons 5 CW Control work 10 HA1 Home assignment 1 30 HA2 Home assignment 2 15 EX Exam 20 TT Total contribution

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Geospatial technology stack (not exhaustive)

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Storage Transmission Processing Visualization DBMS Files Almost all DBMS are geo-enabled

SHP, KML, GeoJSON, GeoTIFF, NetCDF, HDF network protocols WCS, WFS, WMS, OPeNDAP

Libraries in Java, Python, R, JavaScript, …

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Geospatial theory stack (not exhaustive)

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Notations Topology Processing GPS, WiFi, geohash, … Projections

ISO/IEC standard

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The technologies and theory are building blocks for solving real-world tasks

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The technologies and theory are building blocks for solving real-world tasks

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Example task: Because of dramatic traffic increase, the town planners want to widen the main road and add a second lane. The lane width is 20 meters. Find properties that must be demolished. main road

new lane (its central line)

house tree

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The solution (DBMS, WKT, Buffer, Topology, SQL, …)

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LINESTRING (290 230, 330 250, 390 260, 440 260, 495 252, 535 238, 560 220, 580 190, 590 150)

main road house tree

new lane (its central line)

DBMS

SELECT a_geom, address, owner FROM city_database WHERE ST_Intersects ( ST_Buffer( ST_GeomFromText("LINESTRING (290 230,…) ",4326), 10), a_geom)

POLYGON ((325.5278640450004 258.94427190999915, 326.90755828109235, ….))

BUFFER (ST_Buffer)

WKT: ISO/IEC standard

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Consumers of geospatial data

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