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GEOMATICS 23-01-2021
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LAN
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drought
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File: ndvi.php
<?php include ("session.php"); include("header.php"); ?> <title>Drought Management Support System</title> </head> <form action="ndvi.php?name=<?php echo $var ?>" method="post" > <body> <table style="text-align: left; width: 98%; height: 10%; margin-left: auto; margin-right: auto;" border="0" cellpadding="0" cellspacing="0"> <tr> <td background="image/back1.jpg"><table width="99%" border="0"> <tr> <td valign="top"><table width="98%" border="0"> <tr> <td><p align="justify"><span class="style3"><strong>Normalized Difference Vegetation Index (NDVI)</strong></span></p> <p align="justify"> <br /> Among the various vegetation indices that are now available, Normalized Difference Vegetation Index(NDVI) is widely used for operational drought assessment because of its simplicity in calculation, easy to interpret and its ability to partially compensate for the effects of atmosphere, illumination geometry etc. The Normalized Difference Vegetation Index (NDVI), is calculation, based on several spectral bands, of the photosynthetic output (amount of green stuff) in a pixel in a satellite image. It measures, in effect, the amount of green vegetation in an area. </p> <p align="justify">NDVI calculation are based on the principle that actively growing green plants strongly absorb radiation in the visible region of the spectrum, while strongly reflecting radiation in the near infrared region. Given the following abbreviations: NIR: Value of Near-infrared radiation from a pixel. </p> <p align="justify">VIS: Value of visible red radiation from a pixel. </p> <p align="justify">NDVI from pixel is calculated from the following formula. </p> <p align="justify">NDVI= (NIR – VIS) / ( NIR+VIS) This formula yields a value ranges from -1 to +1.</p></td> <td width="40%" valign="top"><br><br><br><br><div align="right"><img src="image/ndvi.jpg" alt="" width="225" height="225" align="top"></div></td> </tr> </table> <p align="justify"> </p> </td> </tr> </table></td> </tr> </table> </body> </html> <?php include("footer.php"); ?>