Mom who Maps

Creating a Standalone GIS Application Sat, 02/07/2009 - 22:03 — Gary Sherman In this example we are going to begin to build a standalone GIS application using Python and the QGIS libraries. We'll start simple by creating an application to load and display a shapefile. In later posts we'll enhance the application to provide some map tools and other features. Requirements To build the application we need the following tools installed: QGIS 1.0 PyQt4 Qt 4.3 or higher and the development tools (Designer) Python 2.3 or better Testing the Environment Before getting started we need to test our development environment to make sure everything is in place. First we need to make sure Python can find the QGIS bindings. From a terminal or command shell on Linux or OS X: export PYTHONPATH=[path to]/share/qgis/python From a cmd shell on Windows: set PYTHONPATH=[path to QGIS]\python If you are using the OsGeo4W install of QGIS, all you need to do is start the OsGeo4w shell. No set...

The Volcano and the Buffer Mon, 04/27/2009 - 20:19 — Gary Sherman Here in Alaska we have over 130 volcanoes with more than 50 being active in about the last 250 years. Presently Mt. Redoubt is in an eruptive phase and has been since March 22. Ash from the volcano has fallen in a number of communities and areas throughout the state. A couple of weeks or so ago the reports from the Alaska Volcano Observatory indicated the ash was falling within 30 miles of the volcano. I decided to do a quick analysis to see what areas might be affected. This is an example of simple analysis with GIS. We just get the location of the volcano and create a 30 mile buffer and then visually determine the affected areas. To do this we need data for towns and the location of the volcano. We could use a volcano layer if we had one, but in this case I'm going to use a simple method to create a point shapefile from text data. The AVO website indicates that Mt. Redoubt is located at Latitude...

PART 1 NOTES: common formats •Shapefiles(.shp) •GeoTIFForTIFFwithworldfiles(.tif,.tfw) •JPEGwithworldfiles(.jpg,.jpw) •GPSdata(.gpx) other vector formats •ArcInfoBinaryCoverage •ArcInfoInterchangeFile(.e00 •MapInfo(..tab,.mid,.mif) •SDTS,adatatransferstandardforbothvectorandrasterdata1 •TopologicallyIntegratedGeographicEncodingandReferencing (TIGER)data,usedanddistributedbytheU.S.CensusBureau •DigitalLineGraphics(DLG) other raster formats •ERMapperCompressedWavelets(.ecw) •ErdasImagine(.img) •DigitalElevationModels(.dem) •JPEG2000(.jp2,.j2k) •Multi-ResolutionSeamlessImageDatabase(MrSID)(.sid) •GTOPO30,aglobaldigitalelevationmodel(DEM)derivedfroma numberofrasterandvectorsources Note: use an OSGIS software that uses GDAL/OGR for accessing raster and vector data (GRASS and QGIS) data format deliverable over the web: Open Geospatial Consortium website http://www.opengeospatial.org WebMappingService(WMS), PostGIS -Creating a POSTGis-enabled database: WebFeaturesService(WFS), WebCoverageService...