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
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