Google’s Maps API is notoriously stingy in this regard, with its terms of service even limiting your right to display content derived from Google imagery on a map that isn’t also provided by Google. tracing building footprints or other cartographic features), you should consider a paid option that allows for derivative works to be produced. If you’re considering deriving a commercial product from the imagery you’re browsing (e.g. Google has to do this because otherwise they could never manage all the math of multiple projections.Some other great sources of non-commercial, non-downloadable imagery are: This may not matter for a small place like Charlottesville, but can entail major problems for a large region like Asia. ( ) This introduces distortions to a map that are very difficult to correct. Google also provides satellite imagery in a single Mercator projection called the “Google Projection”. This means that specialized work is necessary to get Google resources to work with other GIS resources, rather than just implementing them directly as WMS as one might do for OpenGIS-based resources and services. Google Maps and Google Earth do not use the OpenGIS-standard WMS service API, but rather a proprietary API for interfacing with other data streams and projects. Many people are familiar with Google Maps and Google Earth and may wonder why it is not simply sufficient to use them. At a cost, other imagery vendors provide sub meter imagery. Zoom in far enough and TerraMetrics is eventually replaced by DigitalGlobe for the highest resolution. If you manually zoom out, NASA appears on the list. As you zoom in, NASA falls off the list and is replaced by higher-resolution imagery from Terra Metrics, Digital Globe, or another source.įor example, a Google Maps search for "Tibet" by default zooms to a TerraMetrics image. Landsat imagery) in the copyright notice when zoomed out to a very distant vantage point. This notice changes as you zoom in according to the imagery resolution provided by each vendor. In both Google Maps and Google Earth you’ll see a copyright notice along the bottom of the screen identifying Google’s imagery source. As you zoom in, you are viewing commercial satellite imagery that Google has purchased. Google Maps and Google Earths only uses Landsat imagery for its most distant views. The resulting resolution is a compromise between 15 and 30 meters per pixel. Pansharpened images are created after the fact by post-processing the Landsat imagery. Pansharpening is a software technique merging elements of the black and white magery with the lower resolution color imagery to increase visible detail. The Landsat 7 sensors collect 15 meter resolution black and white imagery, but only 30 meter color scenes. The highest resolution free satellite imagery is Landsat 7 from NASA. In addition, the satellite imagery is useful to allow for visualization of the terrain. Satellite imagery is very useful for examining regions to locate the coordinates of specific features, if the imagery is high enough resolution to see enough detail. THL Toolbox > Places & Geography > Satellite ImageryĬontributor(s): David Germano, Kelly Johnson
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