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Geo spatial python princeton pug
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- 2. GeoSpatial Python • GeoSpatialanalysis • Key concepts • Representations of the earth • Projections • Coordinate Systems • Geometry • Remote Sensing • GeoFunctions • Software • Geo Foundations • Python
- 3. About me • byday • Traveling salesman in wireless communications • Network neurologist • Mobile networking • by night • Pythonista (middling) • Music • Photography • Education • West Windsor Plainsboro High School • Thomas Edison State College, BSBA • Lehigh University, MBA DonHolloway DonHolloway DonHolloway
- 4. Geospatial Fundamentals • Statisticalanalysis + place • Spatial • Points of Interest • Geolocation • Geometry • Analysis • Big Data • Familiar tools • Numpy • Pandas • Pillow • Visualization Terrestrial scale - shape and size Naming of places Need for rigour – coordinate systems and datums 2D vs 3D perspectives on geospatial issues
- 5. Representations of theEarth Map Globe Oblate Spheroid datum • a set of reference points on the Earth's surface against which position measurements are made • North American Datum of 1927 (NAD27) • NAD83 (adopted internationally as GRS80) • World Geodetic System 1984 (WGS84)
- 6. Projections Projections convert sphericalcoordinates (lat-long) to planar coordinates. Three primary types: • Azimuthal: projection onto a planar surface • Cylindrical: projection onto a cylinder, which is then ‘unrolled’ to a plane. • Conic: projection onto a cone, which can be unrolled to a plane. All projections create distortions of shape, area, or distance Web Mercator (EPSG:3857) – Used by Google maps, OpenStreet Maps • Cylindrical – Uses ellipsoidal coordinate data, spherical calculations
- 7. Coordinate Systems • Geographic(Lat-Long) • UTM (Universal Transverse Mercator) • Worldwide system with units in meters • In Northern hemisphere, Y coordinate (northing) is distance in meters from equator • X-coordinate (easting) is distance in meters east from a central meridian for a zone • Consists of 60 zones each 6 degrees wide • State Plane Coordinate System (SPCS) • Different for each state • Some states divided into multiple zones with different grid systems for each zone • Either Transverse Mercator (NJ) or conical (PA * 2) projections
- 8. Geometry (vectors) • VectorData • Points, Lines, Polygons • Spatial representation • WKT, WKB • Simple features spec • Points of Interest • Shapefiles • Semi Proprietary • Loosely structured • Decades of data • GeoJSON • Emerging open standard • Tools • GEOS / Shapely • OGR / Fiona • Geojson • PyShp • dbfpy https://njgin.state.nj.us/NJ_NJGINExplorer/index.jsp NJ Municipalities Earthquake epicenters
- 9. Remote Sensing Imagery(Raster) •“Image-like” • Typical formats • TIFF (tags inherent) • JPEG (exif), GIF, BMP and PNG(world files) • Alternates • BLOB, NetCDF • Resolution is specified in ground distance that each cell represents • GDAL / Pillow / OpenCV Landsat 8 – acquired 2/2/2016
- 10. Geospatial functions • BoundingBox • Convex Hull • Buffer / erode • Dissolve • Generalize • Intersection • Merge • Point in Polygon • Union Environment: Windows Python 3.4 Anaconda package
- 11. Software • Geo Foundations •GDAL,OGR, Geos, PROJ4 • Geo General Purpose • QGIS, PostGIS, MapServer • Analysis • Pandas, Numpy, Pillow, PostGIS, Matplotlib • Python • geoPandas*(pandas), shapely (geos), pyproj(proj4), Fiona(OGR), geopy (geolocation), Descartes(matplotlib),
- 12. References • Resources • Wikipedialist of GIS software - et.gy/1Q327gk • OSGeo project list – www.osgeo.org/ • Data • NJ Shape files - https://njgin.state.nj.us/NJ_NJGINExplorer/index.jsp • Raster images - http://earthexplorer.usgs.govPython libraries/ • Shapely http://toblerity.org/shapely