Free For All! – Georeferenced Image of the Earth
Have you ever needed a full view of the earth in a photo-realistic format–for example, to use in a movie trailer or perhaps as a backdrop in an online web mapping application? If so, my Free For All! this month is the ideal solution: a 1-arc minute view of the entire earth created by our friends at NOAA. This image is a shaded relief map derived from the ETOPO1 dataset which contains a wide variety of bathymetric and land elevation products. By coloring lakes, oceans and seas blue; land areas green and brown; and then ice sheets and glaciers shades of white, NOAA has created a photo-realistic view of our planet at 1-arc minute resolution.
At the equator, an arc-minute is approximately 1.8 kilometers (North-South) by 1.8 kilometers (East-West). As you move away from the equator, our planet narrows as would any spheroid. Therefore, an arc-minute also changes in shape whereby at 50 degrees latitude the resolution is still 1.8 km North to South but is now ~1.2 km East to West. When brought into ArcGIS, the ETOPO1 relief map supports zooms up to ~1:7,000,000. As such, this imagery layer is appropriate for views of regions (e.g., the Midwest and the South) as opposed to more limited views of cities, counties and even a state.
There are two formats of the ETOPO1 shaded relief available for download. One features ice sheets and glaciers that are larger than 100 sq km–you can download the ice sheet version here. In the bedrock version, ice sheets have been removed–you can download the bedrock version here. NOAA also offers an online application that lets you clip out the coverage you need as well as up-sample the resolution if need be–it can be accessed here.
Brock Adam McCarty
Map Wizard
(720) 470-7988
