GIS and Remote Sensing Tools, Tips and more ..

In this section, I am showing the 3 basic steps to connect PostGIS database with a widely used open source desktop based gis, QGIS.  Step1: Install PostGIS with Spatial database support extension i.                     If PostgreSQL is already installed è Launch ‘Application stack builder’ from startup menu in windows 7. ii.                   Select the appropriate instance of PGSQL from dropdown list and Click NEXT. iii.                 Expand ‘Categories’ è Expand ‘Spatial Extensions’ è Select appropriate PostGIS version(1.5)  for the already installed PGSQL version(8.4). iv.                     Follow the instructions to inst...

I was writing ArcGIS extension for Geoprocessing using JAVA and ArcObjects 10. My need was to process about 1000 PRISM raster datasets globally to compute various environments. My application did work up to 45- 50 raster files without any problems in loop, then if fails with “ AutomationException 0x80004005 - Unspecified error ”. If I restarted the application again works for next 45-50 raster files and then crashes with the same error. I still couldn’t figure out what was the exact cause for application failure-my guess is it may be due to memory management/garbage collection problem among ArcGIS COM objects and JAVA objects. Fortunately, I solved this issue by reinitializing ArcGIS engine (hope re-initialization breaks the locks and flushes the garbage) after 20 raster files processing. Now, the application works well without any breaks but little bit slower while initializing the ArcGIS engine after 20 raster files processing.

I was  experiencing "ERROR: No categories found in raster map" during v.rast.stats computation (Zonal statistics in terms of ESRI, ArcMap). From the GRASS documentation, I learned that v.rast.stats is only designed for vector areas, not for lines, points,face,centroid,boundary, etc. Therefore, I  unchecked all the properties of vector layer except area as in figure 2, and run the v.rast.stats- worked like charm..

To clear the console: CTRL + L To seek help: ?command_name To view type:class(object_name) To maximize the console print view: Options(max.print=999999) To list active objects in R: ls() To Remove single object:rm(object_name) To Remove all Objects in R: rm(list=ls()) To remove all the objects - except 'a': rm(list = ls()[-a])

From last couples of week, I have been involving to develop a interactive web interface for West Nile virus incidence dissemination across the conterminous US from 1999-2011. The image on the right shows one of my accomplishment using Geoserver,Openlayers,jQuery, PostgreGIS,and Google API. The project is about to launch online, then I will post a complete link of the project to let you guys play around it. Click to visit: Web application I am willing to help any one who is stuck with web maps/visualization and also seek constructive criticism on web stuffs.

Open Source software has come a long way in recent years for storing, manipulating and presenting spatial data. The Openstreetmap (www.openstreetmap.org) project is a great example of what can be achieved using open software and open data. This presentation will look at using a combination of postgis, geoserver and openlayers to process, store and present vector and raster map data. The presentation will also demonstrate OGC web mapping protocols, map projections, spatial toolkits (including uDig, gdal and ogr) and sources of free geospatial data. Gavin Jackson is a software engineer working in the Spatial Team on the Atlas of Living Australia project (www.ala.org.au). Bio: A software engineer with 10 years experience (BInfTech ANU, Msc UNSW), he has worked in a variety of environments, including Department of Defence (IT Security), CPT Global (Stress and Volume Testing), Les Mills (Software Engineer) and, currently, CSIRO (Spatial Software Engineer).  He has long been an advocat...

Are you wondering on MODIS products' naming convention? Don't worry !!. This is the time to dig out MODIS names. Let's say you have few MODIS products. Nadir BRDF-Adjusted Reflectance  ( NBAR ): MCD43B4.A2000185.h25v03.005.2006299173851.hdf MODIS Land Surface Temperature Products: MOD11A2.A2002241.h12v02.005.2007222102136.hdf MCD43B4 or MOD11A2- MODIS Product Short Name A2000185 or A2002241 - Julian Date of Acquisition (A-YYYYDDD) h25v03 or h12v02- Tile Identifier (Tile location- horizontalXXverticalYY) 005 - Collection Version 2006299173851 or 2007222102136- Julian Date of Production (YYYYDDDHHMMSS) The YYYYDDD of above products equivalent to 2006299 and 2007222, which means Year:2006 Day of Year:299 (OCT 25, 2006) & Year:2007 Day of Year:222(AUG 09,2007) hdf - Data Format (HDF-EOS) Cheers !!