Published on January 20, 2008
r.vi: A GRASS GIS Tool : r.vi: A GRASS GIS Tool November Seminar-２８/11/06 Shamim Akhter PhD Student AIDA Lab Department of Information Processing Tokyo Institute of Technology, Japan VI: Vegetation Index: VI: Vegetation Index Indicates how plant and soil respond to contact with light energy. Natural surfaces are about equally bright in the red and near-infrared. An exception is green vegetation. Red light is strongly absorbed by photosynthetic pigment (chlorophyll) while Near-infrared light is highly reflected by the same. That means the area of bare soil having a little or no green plant material will appear similar both red and infrared wavelengths. While area with much green vegetation will be very bright in the near-infrared and very dark in the red part spectrum. Some Hints related RS : Some Hints related RS Satellites and Digital cameras measure light as digital number- DN If these sensors are calibrated, the DN can be converted to radiance, which is the amount of light coming from the surface. If the amount of irradiance (incoming light) is known, then the surface’s reflectance can be calculated as the radiance divided by the irradiance plus compensation for atmospheric clarity at the time the image is acquired. Reflectance is by far the hardest value to get, but it is the most valuable since it is a characteristic of the surface itself and not affected by the intensity of light shining on it. Different Vegetation Indexes: Different Vegetation Indexes The RVI-Ratio Vegetation Index The NDVI-Normalized Difference Vegetation Index The IPVI-Infrared Percentage Vegetation Index The DVI-Difference Vegetation Index The PVI-Perpendicular Vegetation Index The WDVI-Weighted Difference Vegetation Index The SAVI-Soil Adjust Vegetation Index The GARI-Green Atmospherically resistant Vegetation Index The MSAVI-Modified Soil Adjusted Vegetation Index The MSAVI2-Second Modified Soil Adjusted Vegetation Index The GEMI-Global Environmental Monitoring Index The ARVI-Atmospherically Resistant Vegetation Index The GVI-Green Vegetation Index r.vi: r.vi GRASS Raster module. To calculate 13 VI. Developed by (09/10/2006) Baburao Kamble, AIT, Thailand Yann Chemin, AIT, Thailand How works: How works Methodology: Methodology Necessary Grass Functions: Necessary Grass Functions G_find_cell “Looks for the raster file name in Database” G_raster_map_type “Return map type information, CELL_TYPE (int), FCELL_TYPE(float), DCELL_TYPE(double) ” G_open_cell_old “to open the CELL file” G_get_cellhd “Get the raster header file information” G_allocate_raster_buf “allocate an array of CELL/FCELL/DCELL type based on the given column value” G_window_rows “Return no of rows in active region” G_window_cols “Return no of rows in active region” G_open_raster_new ”new raster file will open” G_get_raster_row “get the specific row values from the image to a buffer” G_put_raster_row “put the specific row value from the buffer to image location” Parallel Methodology: Parallel Methodology Need Help: Need Help r.vi.grid viname=ndvi red=p126r050_7t20001231_z48_nn30.tif nir=p126r050_7t20001231_z48_nn40.tif vi=vi7 Fri Nov 24 03:15:38 2006 225ms 346us: Client: dim3: Error: ngcllContextInitialize2nd: Configuration file error. Fri Nov 24 03:15:38 2006 225ms 578us: Client: dim3: Error: ngclContextConstruct: Can't initialize the Ninf-G Context. Fri Nov 24 03:15:38 2006 226ms 244us: Error: ngiSignalManagerStop: Signal Manager is not started. Fri Nov 24 03:15:38 2006 226ms 579us: Error: ngcliNinfgManagerFinalize: Can't stop the Signal Manager. Fri Nov 24 03:15:38 2006 226ms 799us: Fatal: ngcllContextFinalize2nd: Can't finalize the Ninf-G Client Manager. Fri Nov 24 03:15:38 2006 227ms 1us: Error: ngclContextConstruct: Can't finalize the Ninf-G Context. Fri Nov 24 03:15:38 2006 227ms 202us: Error: grpc_initialize: Failed to construct the Ninf-G Context. December, 2006: December, 2006 Implement this program into Globus-Ninf-G Testbed. Analysis the time in both Serial and Parallel version. Get different data sets and compare the improvement curves. Aim is to provide the RS user a compact tool for r.vi.grid and r.vi.mpi as GRASS GIS distributed processing examples.