Satellite Imagery Sources
We use many different sources of satellite imagery, from NASA’s Blue Marble Next Generation imagery at 500m resolution to TerraMetric’s 15 meter Landsat 7 ETM+ imagery that is used in Google Maps and Google earth. Our lowest resolution datasets, 1000m, 500m and 250m are used in making world maps, continent maps and maps of large countries. These are enormous images and can support enormous print sizes. For example a 500m dataset can support a very high resolution world map printed as large as 18ft x 36ft with no loss of detail. Such an image, when printed in resolutions typical of billboards etc. will support far larger sizes.
For Satellite Imagery Maps of individual States of the USA we use 90 meter data from the United States Geological Survey (USGS). To make maps of smaller areas (e.g. Delaware Bay, Island of Sicily, Ireland etc.) we use 15 meter data from TerraMetrics. For large scale maps or images (maps of small areas such as a county or smaller) we can use the United States Department of Agriculture (USDA) 1 meter Aerial imagery for anywhere in the continental USA.
All our satellite imagery is derived from the best available seamless satellite data and is either cloud free or substantially cloud free. We enhance some of our satellite imagery datasets in the following ways a) small global adjustments to brightness and contrast that make it significantly easier to distinguish natural features and b) we sometimes combine imagery from other satellites (for ocean bathymetry or polar ice for example) in order to achieve a better final product. Except for our GeoSphere Image® dataset and most of the images in our Satellite Art category, which are “false color” images, our satellite imagery is near true-color.
Satellite Imagery Datasets
Click the images below for larger views.
NOAA:TIROS-N Geosphere Land 1000m
This image, known as the GeoSphere Image®, was created in 1997. It is cloud free, created from multiple whole-earth mosaics of satellite scenes, utilizing two visual bands and three thermal bands from the NOAA TIROS-N satellite. The land cover image was combined with high resolution hydrology and elevation data to produce the final image making it easier to distinguish natural features (such as rivers, mountains and forests). It has a 30 arc second resolution (1 pixel per km at the equator) resulting in an image 21,600 x 43,200 pixels that can support a high resolution printed image up to 6ft x 12ft in size (1.8m x 3.65m).This is “false color” satellite imagery as a result of being enhanced and processed to make it easier to distinguish physical features. It is considered the best imagery choice when the map is to be highly annotated with country names and or capital cities etc. It is not of sufficiently high resolution to make maps of mid-sized or small countries.
NASA: MODIS Land August 500m
A near true-color image of earth that is largely derived from NASA’s Blue Marble Next Generation (BMNG) image for August 2004. BMNG imagery is seamless and cloud-free, collected with NASA's Moderate Resolution Imaging Spectroradiometer (MODIS), flown on the Terra satellite in 2004. The satellite imagery is relief shaded based on land topography by overlaying it on the 3 arc-second SRTM digital elevation Model (DEM). We have replaced the Polar sea ice imagery with imagery that is based on a combination of sources including MODIS data and observations of Antarctica made by the National Oceanic and Atmospheric Administration's AVHRR sensor (Advanced Very High Resolution Radiometer). We have also made a slight global adjustment to the brightness and contrast, to help distinguish natural features. Colors have not been adjusted individually. It has a 15 arc second resolution (1 pixel per 500m at the equator) resulting in an enormous image size of 43,200 x 86,400 pixels that can support a high resolution printed image up to 12ft. x 24ft. (3.65m x 7.3m). The ocean color is very dark but not completely black. The less dark color indicates growth of plankton.
NASA: MODIS GEBCO Land & Bathy 500m
The same as NASA:MODIS Land August 500m imagery but with bathymetry included. Ocean bathymetry is derived from the RAMP II dataset (Radarsat Antarctic Mapping Project Digital Elevation Model), Version 2, 2001 and GEBCO (General Bathymetric Chart of the Oceans), 2003. (Bathymetry is the name for topography of the ocean floor). The blue ocean colors of this dataset are spectacular.
NASA: MODIS Land February 500m
Similar to the NASA: MODIS Land August 500m imagery except the data was captured in February 2004. The snow cover of the northern hemisphere's winter is very evident.
NOAA: TIROS-N PVisions Land & Ice 1000m
This image of land and polar ice from Planetary Visions is derived from data collected by the Advanced Very Hign resolution Radiometer (AVHRR) instrument on board Polar Orbiting Advanced TIROS-N (ATN) satellites from the period beginning April 1992 and ending in June 1994, operated by NOAA.
The ocean imagery is derived from data collected by the Coastal Zone Color Scanner (CZCS) on board the Nimbus 7 satellite, launched in October 1978, under the control of NASA and NOAA. The satellite maintains a near polar, sun-synchronous orbit at an altitude of 955 km. The CZCS is a scanning multispectral radiometer designed specifically for the remote sensing of Ocean Color parameters from an Earth orbiting space platform.
Sea Ice imagery is derived from data collected by the United States Air Force (USAF) Defense Meteorological Satellite Program (DMSP), Operational Line Scan System (OLS), known as USAF DMSP OLS. The Arctic Sea Ice data is from June 1986 to May 1987 and the Southern Ocean Sea Ice is from a two year period from November 1985 to November 1987.
The whole world image is seamless, cloud free and near true color. It is the result of processing over 30,000 images from six space agencies in which cloud free and maximum greenness scenes are selected and blended into a single seamless mosaic. Shading is achieved by draping the land imagery over the GTOPO30 DEM and is overlaid by the river network.It has a 30 arc second resolution (1 pixel per km at the equator) resulting in an image 21,600 x 43,200 pixels that can support a high resolution printed image up to 6ft x 12ft in size (1.8m x 3.65m).
NASA: MODIS GEBCO Land & Bathy 250m
The best images at 250 meter resolution have been selected from NASA’s archive of MODIS (Moderate Resolution Imaging Spectroradiometer) data. Shading is achieved by draping the land imagery over digital Elevation data.
Unlike our other NASA: MODIS datasets, this 250 meter MODIS derived imagery is not temporal, i.e. there is only one image for the entire 12 month period.
In some cases ocean bathymetry is included. The bathymetry imagery we use includes GEBCO (General Bathymetric Chart of the Oceans), 2003 which at 30 arc seconds resolution (1 pixel per km at the equator), is lower resolution than the land imagery (250m per pixel). Bathymetry is the name for topography of the ocean floor.
USGS: Landsat State Mosaics 90m
State satellite image mosaics are created from color balanced, histogram matched Tri-Decadal Landsat ETM+ Pan-Sharpened scenes that are Orthorectified, then draped with National Elevation Dataset (NED) data. Histogram matching is achieved as follows. A scene in the middle of the State is chosen as the base scene for histogram matching and it is first color balanced. Then adjacent scenes are dropped in and histogram matched to the base scene. As scenes further away from the base scene are added, these scenes are histogram matched to the adjacent scenes that they overlap and so on for the next row of scenes.
Map scale, principal cities and towns are subsequently included.
While the images have been georeferenced, no map projection or datum information is provided. The result is a series of state maps, unparalleled in the portrayal of topography and natural features. They provide a better understanding of the topography of each State than any unenhanced satellite imagery could achieve.
TerraMetrics: Landsat 7 ETM+, Land 15m
TruEarth® 15-meter imagery by TerraMetrics, Inc.
This is the very same imagery that is used in Google Maps and Google Earth, without the watermarks, of course. TruEarth® 15-meter imagery provides complete, best-available, natural-color, substantially cloud-free, global land coverage (except Antarctica) at 15-meters-per-pixel resolution.
All imagery is georeferenced and all derived maps conform to a known map projection and datum. The maps will usually include major administrative boundaries, latitude & Longitude and a map scale. The result is maps that surpass what can be found in Google Earth and Google Maps.
USGS: EROS Landsat-7 Satellite Art
These images were created by the USGS's Earth Resources Observation and Science (EROS) Center. Landsat 7 images are color composites, made by assigning the three primary colors to just three of the many bands (wavelengths) of the Enhanced Thematic Mapper (ETM+) sensor.
These images are not color photographs, they are "false color" images (green fields won't necessarily look green in the image). One common way that primary colors are assigned to bands can be easily remembered using the mnemonic; RGB = NRG (Red, Green, Blue = Near Infrared, Red, Green, or "energy") that is ETM+ bands 4, 3 and 2 respectively.
This common band combination makes vegetation appear as shades of red, because vegetation reflects a lot of near infrared light. The brighter the red, the healthier the vegetation. Soils with little or no vegetation will range from white (for sand) to greens and browns, depending on moisture and organic matter content. Water will range from blue to black. Clear, deep water is dark, and sediment-laden or shallow water appears lighter. Urban areas look blue-gray. Clouds and snow are both white.
This assignment of colors is only one of many possible combinations. Any combination of bands can be represented by red, green, and blue.
USGS: EROS ASTER Satellite Art
Similar to the USGS: EROS Landsat-7 Satellite Art imagery, except the data was captured with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the Terra Satellite.