Skip to main content

Popular posts from this blog

Basic of Remote Sensing III

By
Contents Advantages Limitations Applications Advantages of Remote Sensing : Provides a synoptic view over a large region; Offers Geo-referenced information and digital information; Most of the remote sensors operate in every season, every day, every time and even in tough weather; Limitations : Can be expensive; Can be technically difficult; Not direct; Measure surrogate variables e.g. reflectance (%), brightness temperature, backscatter; Applications of Remote Sensing Urban & Regional Planning Scope: Mapping & updation of city/town maps  Urban sprawl monitoring Town planning Facility management  GIS database development Benefits: Better decision support, planning & management Rapid information updation Infrastructure development monitoring Spatial information analysis Agriculture Scope: Crop acreage estimation Crop modeling for yield & production forecast / estimation Crop & Orchard monitoring Soil sensing Mapping
Post a Comment
Read more

Basic of Remote Sensing IV

By
Sources of Electromagnetic Energy There are three main sources of  electromagnetic radiation that are used in  remote sensing:  Solar radiation (natural radiation from the  sun)  Terrestrial radiation (natural radiation  emitted by Earth's surface)  Artificial radiation (from a remote sensing  system) Solar Radiation The Sun yields a continuous spectrum of EM  energy. This Incident radiation can be reflected  from the Earth's surface. This process produces a large amount of  short wavelength energy (from 0.4 - 0.7 µm;  blue, green, and red light). It can also be emitted by the Earth's  surface. Such emitted radiation is typically  of a longer wavelength, in the middle and  far infra-red wavelengths. Interacts with the atmosphere and surface  materials (reflect, absorb).  Since the Sun has a much higher temperature  (6000 degrees K) than the Earth (303 degrees  K), so the overall energy radiated by the  Earth is lower and has its peak at a longer  wa
Post a Comment
Read more

Resolution

By
Resolution: sensor characteristic that affect what can be seen in an image Source: NASA Spatial resolution Spectral characteristics Temporal characteristics Sensor sensitivity SPATIAL RESOLUTION Spatial resolution refers to the amount of detail that can be detected by a sensor. It is the smallest unit measured; Images where only large features are visible are said to have coarse or low resolution. In fine or high-resolution images, small objects can be detected. Detailed mapping of land-use practices requires a much greater spatial resolution. Size of an image pixel in ground dimensions. Usually represented by the length of one side of a square (i.e., 30m resolution). The spatial resolution of passive sensors depends primarily on their Instantaneous Field of View (IFOV). The IFOV is the angular cone of visibility of the sensor (A) and determines the area on the Earth’s surface which is “seen” from a given altitude at one particular momen
Post a Comment
Read more