ASTER: Satellite Sensor

A color infrared composite (bands 321) of an ASTER acquisition on April 28, 2007. This subset is centered on an area of forested and clear-cut forest lands. A portion of Sam Rayburn Lake is also visible. These features are located in East Texas north of the city of Jasper. The scale of the image is 1:60,000.

A NASA EOS (Earth Observing System) satellite called Terra (EOS AM-1) carries the ASTER instrument. Terra launched on Dec. 18, 1999, …

Web Mapping: An Introduction

ortho image with contours

The term “Web mapping” constitutes both the technology and art of sharing maps on the Internet.

The simplest Internet-based maps are static, such as images (i.e., jpegs or tiffs) that do not allow users to change the components, extent, or appearance of the map. These maps are the easiest and simplest to share because all that is required is placing the image on a Web server and telling others where to find it. At the opposite end of the …

LIDAR Derived Products

Lidar Derived Shaded Relief

What Products Can be Generated from LIDAR?

LIDAR provides a cost-effective means to collect digital information about the Earth’s surface. Using LIDAR, we can obtain several “layers” of information from the landscape through a series of LIDAR returns. The first return of information to a LIDAR sensor would, for example, be associated with the highest features in the landscape (typically treetops, tops of buildings, etc.). Following data returns would be associated with understory vegetation below the initial tree or vegetation …

LANDSAT: Satellite Sensor

A color infrared composite (bands 432) of a Landsat 7 ETM+ acquisition on Nov. 13, 2002. This subset, from path 27 row 39, is centered on downtown Austin, Texas, and shown at a scale of 1:100,000.
A color infrared composite (bands 432) of a Landsat 7 ETM+ acquisition on Nov. 13, 2002. This subset, from path 27 row 39, is centered on downtown Austin, Texas, and shown at a scale of 1:100,000.

NASA developed and launched the Landsat satellites, and the USGS handles the flight operations, maintenance, and management of all ground data reception, processing, archiving, product generation, and distribution. The legacy of Landsat satellites began in 1972 with the launch of Landsat 1. Since …

How to Geotag and Display Pictures in Google Earth

example of a georeference image in Google Earth

Geotag Your Pictures in Google Earth

Have you ever wished you could show people where on a map your photographs were taken? Wouldn’t it be great if you could use a computer-based mapping program to do this? Well, you can. With Google Earth, a digital camera and an inexpensive GPS receiver, you can create and display picture locations, and with a little typing you can add pictures and descriptive text that will display when you click on the picture’s location. …

Protecting cold water streams: GIS tackles thermal loading in urban watersheds

Stream in the woods
Stream in the woods

Cold-water streams are susceptible to a growing problem in rapidly urbanizing areas: thermal loading from heated water that runs off of streets, roofs, and parking lots. A new Dane County, Wisconsin, ordinance is aimed at managing thermal loading, along with other storm water and soil erosion concerns. Using geographic information systems (GIS) and other digital tools, Dane County landowners, developers, and conservationists can now identify land parcels that drain into vulnerable watersheds and predict thermal impacts

GPS Applications in Crop Production

Image:Ae1264p1.jpgGPS and Agriculture

GPS Applications in Crop Production

John Nowatzki, Extension Geospatial Specialist
Vern Hofman, Extension Ag Engineer
Lowell Disrud, Assistant Professor
Kraig Nelson, Graduate Student

The Global Positioning System (GPS) provides opportunities for agricultural producers to manage their land and crop production more precisely. Common names for general GPS applications in farming and ranching include precision agriculture, site-specific farming, and prescription farming. GPS applications in farming include guidance of equipment such as sprayers, fertilizer applicators, and tillage implements to …

Geocaching – Getting Started page

Geocaching – Putting GPS to Work

What is Geocaching?

Geocaching is a recreational activity that involves hiding and seeking objects, or “caches,” usually with the aid of a global positioning system (GPS) receiver. You can think of geocaching as a high-tech treasure hunt. People hide caches and publish their coordinate locations to geocaching Web sites, thereby allowing others to use the coordinates to find the hidden caches. Geocaching is done on the honor system. After discovering a cache, finders sign …

Remote Sensing Resampling Methods

When an image is created through remotely sensed data, it needs to undergo some form of validation procedure using observational and/or sampling techniques. Failure to do so will reduce the confidence in the final product. The following are examples of remote sensing resampling methods:


Nearest neighbor

Nearest neighbor is a resampling method used in remote sensing. The approach assigns a value to each “corrected” pixel from the nearest “uncorrected” pixel. The advantages of nearest neighbor include simplicity and the ability …