GRASS GIS manual: i.in.spotvgt

NAME

i.in.spotvgt - Imports SPOT VGT NDVI data into a raster map.

KEYWORDS

raster, imagery, import

SYNOPSIS

i.in.spotvgt
i.in.spotvgt help
i.in.spotvgt [-a] file=string [rast=string] [--overwrite] [--verbose] [--quiet]

Flags:

-a: Also import quality map (SM status map layer) and filter NDVI map
--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

file=string: Existing SPOT VGT NDVI HDF file (0001_NDV.HDF)
rast=string: Name for output raster map

DESCRIPTION

i.in.spotvgt imports SPOT Vegetation (1km, global) NDVI data sets. After import the digital numbers (DN) are remapped to VEGETATION NDVI values and the NDVI color table is applied. The imported DN map is removed after remapping.

Apparently missing raster cells due to bad pixel quality are reconstructed by the SPOT operating team in the NDVI file. The differences between the filtered (-a flag) and raw NDVI map should be compared.

NOTES

The SPOT VGT files are delivered in HDF4 (Hierarchical Data Format Release 4) format. It is required to have the GDAL libraries installed with HDF4 support.

Export of entire world SPOT VGT maps

When working with SPOT VGT with entire world extent, it is recommended to zoom to w=180W and e=180E instead of using the map extent for map export. These entire world SPOT VGT data are exceeding -180.0 degree which can lead to unhelpful large East-West coordinates in the exported file. It is also recommended to then use an export command which respects the user settings. Example:

# import:
i.in.spotvgt 0001_NDV.HDF

# export:
g.region w=180W e=180E n=75:00:16.071429N s=56:00:16.069919S res=0:00:32.142857 -p
r.out.tiff -t 0001_NDV out=spotndvi

REFERENCES

SPOT Vegetation (1km, global) NDVI data set server
SPOT Vegetation FAQ
SPOT Vegetation Status Map (SM) - Quality map

AUTHOR

Markus Neteler

Last changed: $Date: 2008-08-17 06:27:35 -0700 (Sun, 17 Aug 2008) $

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