Image Product What is an image An image

Image Product

What is an image? • An image is a rectangular grid of pixels arranged in Rows & Columns. • It has a definite height and a definite width counted in pixels. • Single elements are called pixels or picture elements • For each pixel, the measurements are stored as digital values or DN. Values are stored. • Each pixel is square and has a fixed size on a given display. • For each wavelength, a separate layer is stored.

What is an image?

Analysis • A range of approaches are used to analyze remotely sensed data. These approaches can be broadly grouped in to three categories • Measurement • Classification • Estimation

Measurement Analysis • Remotely sensed data can be analyzed to provide measurements of features or phenomena on the earth’s surface. • Earth surface temperature, derived from thermal infrared data are perhaps the most familiar types of remote measurement • Throughout the growing season agriculture Canada monitors the overall condition of important food crops.

Measurement Analysis • This information is used to predict the expected size of the harvest relative to that of previous years and to identify areas where the crop is developing poorly so that remedial action can be taken and short falls in production can be anticipated. • The remote sensing measurement used to assess crop condition is calculated from the reflectance values in the red and near infrared bands obtained from the NOAA AVHRR sensors. • The crop condition index calculated from these data is termed the normalized difference vegetation index (NDVI).

Classification Analysis • Conditions as varied as soil texture, crop types, forest species composition, geological strata and human activities are all routinely assessed by visually interpreting airborne and satellites images. This procedure of identifying and mapping areas with similar characteristics is the most widely used form of classification.

Classification Analysis • The application of theses classification methods complements those of visual interpretation. • The use of patterns, tones and shapes to deduce information tends to be more efficiently done by a human interpreter than by computer analysis. • However, computer techniques are used to derive quantitative measurements from the reluctance data.

Estimation Analysis • Remote sensing based estimation analysis are treated here a separate categories. This type of analysis is used for such assessment as the planted to a particular crop type. • The expected crop production for a region. The forest resources inventory of a region. The information is usually provided in the form of quantities for each administrative or measurement unit. • The objective of an estimation analysis is to produce estimates of total amounts for each of specified region.