Change detection in GIS is a method of understanding how a given area has changed between two or more time periods. Change detection is helpful for understanding the change in forest coverage, ice sheets, and land use. Change detection involves comparing changes between aerial photographs taken over different time periods that cover the exact same geographic area. In ArcGIS, change detection can be calculate between two raster datasets by using the raster calculator tool. Change Detector script from Bruce Harold – From the ArcScript site, this tool that “computes the added, deleted and unchanged features between original and revised editions (or versions) of a data set by considering any combination of geometry and attributes.” To compare the differences between two vector datasets use the Feature Compare tool under Data Management –>, Data Comparison. To create a third GIS dataset showing the difference between two datasets go to Vector –>,GeoProcessing and then select the Difference function. This video looks at change detection to understand changes in a building layer by comparing roof tops between two different files using ERDAS. City Maps: A coloring book for adults is a 94-page book containing 44 maps covering cities from around the world by Gretchen Peterson Sangeeta Deogawanka discusses what it takes to develop a career in Geointelligence whether it be in security, intelligence, policy analysis, first response, technology, software development or consulting. The American Association for the Advancement of Science (AAAS) has produced a manual entitled “Introduction to Remote Sensing of Cross Border Conflicts: A Guide for Analysts” as part of a project by its Geospatial Technology Project staff to understand the use of satellite imagery as a tool for “understanding border conflicts and possible conflict prevention.” Isodistance measures routes of equal time and isochrone measures routes of equal travel times although both are typically represented as bands of polygons. Got MS Excel? Need a simple map? A little known tool in older versions of Microsoft’s Excel is the ability to create simple maps from tabular data. You can create simple chloropeth, chart and dot density maps using data organized by country, state or region. An open source application by definition is software that you can freely access and modify the source code for. Open source projects typically are worked on by a community of volunteer programmers. Open source GIS programs are based on different base programming languages. Three main groups of open source GIS […] GIS is a technological field that incorporates geographical features with tabular data in order to map, analyze, and assess real-world problems. The key word to this technology is Geography – this means that some portion of the data is spatial. In other words, data that is in some way referenced to locations on the earth Source.