These techniques convert the raw DN data to light reflectance at the Earth's surface. These techniques have existed for some time, but are extremely technical and, until now, have not been readily accessible for use by non-remote sensing specialists. These calibration procedures are extremely important for the global change research community for two reasons. First, by converting the images from DNs to surface reflectance, the scholar is making his or her image directly comparable to other images. It also allows for direct comparisons of two similar but geographically distant sites.
Light reflectance is as much as scientific measure as temperature or weight.
But we have yet to capitalize on using it as an important measure of land cover change. The challenge the global change research community now faces is understanding what information content light reflectance provides as a measure of land cover change and how it relates to informing us about other important global change processes. If such relationships can be identified, it raises the possibility that surface reflectance can be used as a proxy for inventorying and mapping global change parameters such as carbon sequestered. Remote sensing analysis relates to the human dimensions of global change in that it captures the outcomes of human actions across the landscape. Analysis can then look at how different land classes have increased or decreased over time.