How to Download USGS Topo Maps for Free
If you’re looking for topographic maps (contours, place names & hydrography) for the United States, the first place to look is the USGS topo maps series.
Articles
Nearest Neighbor Classification in eCognition
Nearest neighbor classification is a powerful approach to classify segmented objects based on specific statistics and training samples chosen by the user.
Append Tool in GIS
The Append Tool adds data from one or more sources of data and puts it into an existing target dataset, without creating a new dataset.
Geodesy: The Mathematics of “Where”
Geodesy is the field of applied mathematics that studies Earth’s shape, orientation, positions and gravity for the past, present and future.
ILWIS – Integrated Land and Water Information Management
ILWIS is free (GNU license) for users around the world for GIS and remote sensing needs. Here are some of the neat features and developments.
Scale Bars, Inset Maps and Ratio Text in Cartography
There are several ways to help readers understand map scale and distance. For example, cartographers use scale bars, locator maps, stated and ratio scale.
Latitude, Longitude and Coordinate System Grids
Latitude lines run east-west, are parallel and go from -90 to +90. Longitude lines run north-south, converge at the poles and are from -180 to +180.
ArcScene vs ArcGlobe – Esri’s 3D GIS Software Differences
ArcScene and ArcGlobe both specialize in 3D. However, ArcScene is for local scenes and ArcGlobe is for global. Find out more differences between 3D software.
Linear Referencing Systems (LRS)
Linear referencing systems (LRS) store relative positions on an existing line feature with m-values for point/line events and linear analysis.
Polar Orbit vs Sun Synchronous Orbit
A polar orbit satellite travels pole-to-pole. For a sun-synchronous orbit, it passes over any given point on Earth’s surface at the same local solar time.