ePOM - Intro to Ocean Data Science - Raster and Vector Data Formats

ePOM - Intro to Ocean Data Science - Raster and Vector Data Formats

• 1.
  RASTER AND VECTORDATA FORMATS GIUSEPPE MASETTI ESCI 872 – APPLIED TOOLS FOR OCEAN MAPPING – INTRODUCTION TO OCEAN DATA SCIENCE Durham, NH – September 10, 2019 V1
• 2.
  TWO WAYS TOREPRESENT THE WORLD • Field Approach • Continuous data without well-defined boundaries • Data smoothly transition from one value to another • Discrete-objects Approach • Objects at fixed locations with distinct boundaries • Data usually represented in vector format: POINT LINE POLYGON
• 3.
  FIELD → APPROXIMATEDREPRESENTATIONS SAMPLE POINTS (IRREGULARLY SPACED) SAMPLE POINTS (REGULARLY SPACED) NODE CELLS TRIANGULATED IRREGULAR NETWORK (TIN) POLYGONS (IRREGULARLY SHAPED) CONTOURS
• 4.
  FIELD → APPROXIMATEDREPRESENTATIONS SAMPLE POINTS (IRREGULARLY SPACED) SAMPLE POINTS (REGULARLY SPACED) NODE CELLS TRIANGULATED IRREGULAR NETWORK (TIN) POLYGONS (IRREGULARLY SHAPED) CONTOURS Raster Grid Data Structure
• 5.
  RASTER GRID →DESCRIPTIVE ELEMENTS Number of Columns NumberofRows (𝑥0, 𝑦0) Cell Size Average cell value No-Data Value Value at the cell center Value at a corner What each value represents?
• 6.
  RASTER GRID →VECTOR DATA → RASTER GRID
• 7.
  RASTER GRID →VECTOR DATA → RASTER GRID
• 8.
  RASTER GRID →VECTOR DATA → RASTER GRID
• 9.
  RASTER GRID →VECTOR DATA → RASTER GRID
• 10.
  GEOSPATIAL DATA FORMATS RASTERVECTOR BATHYMETRIC ATTRIBUTED GRID ARC/INFO ASCII GRID GEOTIFF HDF5 GEOPACKAGE GEOJSON GML IHO S57 KML GPSBABEL ARC/INFO BINARY GRID CAD ECW ENVI ORACLE SPATIAL GEORASTER GMT COMPATIBLE NETCDF GRASS RASTER MBTILES GEOSPATIAL PDF RASTERLITE XYZ USGS ASCII DEM MRSID DWG MICROSTATION DGN ESRI FILEGDB GPX JML GEORSS GTM ASCII VECTORSGRASS VECTOR FORMAT NETCDF ESRI PERSONAL GEODATABASE SPATIALITE OSM ORACLE SPATIAL MAPINFO TAB AND MIF/MID SHAPEFILE
• 11.
  THE GEOSPATIAL DATAABSTRACTION LIBRARY • A translator library for raster and vector geospatial data formats • 214+ raster formats* • 80+ vector formats* (e.g., GeoJSON, GeoPackage, GML, IHO S57, KML, Shapefile) • “It presents a single raster abstract data model and single vector abstract data model to the calling application for all supported formats” (GDAL documentation, 2019) • C++ library with Python binding * Values retrieved from GDAL v.2.4.1 on ePOM server.
• 12.
  GDAL AND NUMPY Open GDALDataset Get Raster Band(s) ReadAsArray() Convert raster band(s) to a NumPy array Process array using NumPy functionalities WriteAsArray() Convert a NumPy array to GDAL raster bands Write GDAL Dataset
• 13.
  GDAL → COMMANDLINE UTILITIES • Raster programs • gdalinfo → Lists information about a raster dataset • gdal_translate → Converts raster data between different formats • gdalwarp → Image reprojection and mosaicking utility • gdal_contour → Builds vector contour lines from a raster elevation model • gdaldem → Tools to analyze and shade DEMs • gdal_rasterize → Burns vector geometries into a raster • gdal_grid → Creates regular grid from the scattered data • … • Vector programs • ogrinfo → Lists information about an OGR-supported data source • ogr2ogr → Converts simple features data between file formats • ogrmerge → Merge several vector datasets into a single one • … (source: gdal.org)
• 14.
  MODULE TASK →READ AND PLOT A BAG FILE
• 15.
  GO TO “INTRODUCTIONTO GDAL” NOTEBOOK
• 16.
  QUESTIONS? Contact me at:gmasetti@ccom.unh.edu