I want to download MODIS product MOD13Q1 to use the Scientific Data Sets (SDS) layers of "250m_16_days_EVI", "250m_16_days_pixel_reliability". MODISTools library in R software provides the capability to download the MODIS data from LP DAAC data center.
I have read the
MODISTools pdf guide which provides the basic understanding of how to use the library to subset the MOD13Q1 data layers by using the points location.
The following subset function which I want to use:
library(`MODISTools`) MODISSubsets(LoadDat = modis.subset, Products = "MOD13Q1", Bands = c("250m_16_days_EVI", "250m_16_days_pixel_reliability"), Size = c(1,1))
LoadDat = modis.subset is the data frame of latitude and longitude points in decimal format and according to
Size = c(1,1) parameter that is used to extract the 1 Km left and 1 Km right from the focal point as extent. But I want to used the extent of whole study area like
lat <- c(23.6947, 37.0894) long <- c(60.8786, 79.3074) period <- data.frame(lat=lat,long=long, start.date=2013,end.date=2014,id=1) MODISSubsets(LoadDat = period, Products = "MOD13Q1", Bands = "250m_16_days_EVI", "250m_16_days_pixel_reliability", Size = c(0,0), TimeSeriesLength = 1)
But here I am confused about using Size parameter that is used to extract the point values. How can I use it to extract all the available data in this extent? And second one is can I use this point information in ASCII file to display a raster in R software? I don't want to download the full tile which contains 250MB and in my case this will be 250GB data if I download all the available data starting from 2000 to 2015.