Monitoring urban vegetation levels
| This is an image of Houston, Texas showing the amount of vegetation around the city in the summer of 1992. It uses the Normalized Difference Vegetation Index (NDVI), where areas of high vegeation show up as white, and areas of little vegetation are dark. The NDVI values are derived from data taken by a satellite; the Landsat MultiSpectral Scanner (MSS) was the source of this image. As you can see, the downtown district of the city has very little vegetation and is thus quite dark, while the outlying regions have a great deal of vegetation and are lighter colored. Residential and suburban areas have a grayish hue due to the combination of buildings and vegetation in those neighborhoods. |
Credit: Museums Teaching Planet Earth
For more info: http://weather.msfc.nasa.gov/urban/