Description Usage Arguments Details Value Author(s) See Also Examples
From a shape/kml file with polygons, the function creates a new shapefile with the grid of all the points inside the polygons.
It takes into account the spatial resolution of the images. A point is created if the center of the pixel is inside the polygon. Therefore, the new shapefile has no more than one point per pixel.
The shapefile is projected with the same projection than the map.
1 | polytopoints(shapefile, shapedir, ndvidirectory, region, Ystart, shapeext = "shp", type = "VITO_CLIP", outname = "buffer", outdir = ".")
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shapefile |
name of the shape/kml file with polygons to be transformed in points. |
shapedir |
path to the shape/kml file. |
ndvidirectory |
path to the ndvi images folder (GeoTIFF files). /cr Please note that paths to files in R can be specified with either "/" or "\\" in Windows OS and with "/" in UNIX OS. |
region |
name of the region, same as in the name of the ndvi images. |
Ystart |
starting year of the analysis (in four-digit format). |
shapeext |
extension of the shape/kml file : "shp" for a Esri shapefile or "kml" for a kml file from Google earth . |
type |
type of nomenclature followed by the NDVI images : "VITO_CLIP", "VITO_VGT" or "GIMMS" (see details for more information). |
outname |
name of the new shapefile. |
outdir |
directory where the new shapefile will be saved. By default, outdir = "."(the current directory). |
More about the variable type :
type = GIMMS : nomenclature from Global Land Cover Facility
[RE][YY][MMM][DDD].[SAT]-VIg.tif
RE : identifies the continent (AF for Africa,AZ for Australia and New Zealand, EA for Eurasia, NA for North America and SA for South America and Central America)
YY : the two last digits of the year
MMM : three-letter abbreviation of the month
DDD : identifies the composite period, 15a denotes the days 1-15 of the month, and 15b denotes the days from 16 to the end of the month.
SAT : identifies the satellite, NOAA-7, 9, 11, 14, 16, or 17 from which the data originated.
type = VITO_VGT : FreeVGT VITO's nomenclature
NDV_[YYYYMMDD]_[REGION]_Extract.tif
YYYY : identifies the year (four digits)
MM : identifies the months (two digits)
DD : identifies the date of the period : "01", "11" or "21" (10-day composite).
REGION : idendifies the region selected while extracting maps
type = VITO_CLIP : nomenclature after clipping the images in a particular region.
[REGION][YYYY]M[MM]P[D].tif
REGION : the region as entered while clipping data.
YYYY : identifies the year (four digits)
MM : identifies the months (two digits)
D : identifies the period (0, 1 or 2).
Nothing is returned but a shapefile is created and saved in the folder outdir under the name outname.
Romain Frelat and Bruno Gerard
1 | #There is no shapefile with polygons for the moment
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