GIS and Remote Sensing Tools, Tips and more ..

The Geographic Information Science Center of Excellence at South Dakota State University developed a web based West Nile virus (WNV) mapping application using Geosever, Openlayers, PostGIS,GeoWebCache, Jquery, Google visualization APIs, and, other open source technologies. This application allows users to pan, and zoom to visualize historical WNV patterns while using a slider bar to navigate through time. Users can click on counties to see -county level time-series graphs, case counts, and total population. The application also supports changing choropleth transparencies, choropleth classifications, and map backgrounds. Methods: A. OpenGeo tools: i.     Open layers ii.    Geoserver iii.   WebGeoCache iv.   PostGIS B. Google APIs i.       Google Maps API ii.      Google Charting API C.      HTML5 These are frequently refereed to as HTML5 technologies. Javascript HTML Canvas ...

I really like Mike's hack for firefox/ IE compatibility and posted from his blog .

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.