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Module 1: Immagine Acquisizione e Correzione

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Image Acquisition and Correction - Lesson Summary

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LiDAR Technique and Applications
LiDAR stands for Light Detection and Ranging. It is a surveying method that measures the distance to a target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor. The difference in laser return times and wavelength can then be used to make a digital 3-D representation of the target. The Five Basic Components of Aerial LiDAR System are: Aircraft, Differentially Corrected GPS, Computer, Scanning Laser Emitter-Receiver Unit, Internal Measurement Unit. Mosaicking Technique and Application. Mosaicking refers to the process of combining spatially overlapping images into single image datasets to produce a spatially continuous image based on an aggregation function. The key idea of image sub-sampling is to reduce the number of pixels in an image. False Topographic Phenomena - Concept Optimal remote sensing data from sun-synchronous satellites of a rugged terrain always suffer from topographic effect. This results in incorrect image interpretation. The appearance of inverse topography is termed as False Topographic Perception Phenomena (FTPP). The Causes of FTPP are: Topographic relief, Sun elevation and azimuth, Hatching and engraving features on the slope, Source-observer position Observer’s Viewing angle, Correction of False Topographic Phenomena The Methods of correcting False Topographic Perception Phenomena (FTPP): Image rotation by 180 degree. Sidereal Relief Model (SRM) based correction, Creating Image Negative, FTPP occurs when the illumination source and the observer are in the same hemisphere. High Spatial Resolution Satellite Images The biggest advantage of High Spatial Resolution Satellite Images is that it gives a detailed view of the coverage area. For a large area, high-spatial-resolution satellite images can be expensive and difficult to acquire, because one would require many orbit data or swath data to cover the large area. The higher the spatial resolution of a satellite image, the smaller the swath width and the temporal resolution. Basic Image Compression Techniques. The Four Basic Compression Techniques are: Chain Codes, Block codes, Run-Length Codes, Quadtrees, LZW Compression technique is the compression of a file into a smaller file, using a table-based Lookup algorithm invented by Abraham, Lempel, Jacob Ziv, and Terry Welch. The popular image formats are: Tagged Information File Format (TIFF) | Graphic Interchange Format (GIF)