How often is NDVI data collected by MODIS?
NDVI is collected by the MODIS satellite platform at 16-day intervals. The issues are (1) downloading the appropriate data, (2) reprojecting this data – not as simple a task as it sounds, and (3) extracting the NDVI values at coordinate points.
How to extract NDVI values from a file?
Click on “Open Input File” and select your MODIS .hdf tile. When the file loads, information will populate the “Input File Info” box and the “Selected Bands” box. Move bands that are not 250m_16_days_NDVI out of the “Selected Bands” box and in to the “Available Bands” box.
How can I extract data from MODIS reprojection?
Download the MODIS Reprojection Tool here; you can log in using your LP DAAC username and password from above. Download the Windows NT +32-bit version of the tool. Next, create a folder in your C Drive and call it MRT. Extract the content of the download into the MRT folder. When extracted, click on the mrt_install.bat file.
What is the scale factor of MODIS data?
Looking at the metadata, you can see that your data have a scale factor. Let’s deal with that before doing anything else. The scale factor is .0001. This means you should multiple each layer by that value to get the actual reflectance values of the data. Great – now the range of values in your data appear more reasonable.
Where is the site Pixel in MODIS NDVI?
In the below explanation, we will download MODIS NDVI data via an R script. Under ‘Download data’ tab and table, via the website, you can see a small link named Pixel Numbering Scheme, Click it to see that the blue pixel (i.e. pixel number 545) is the “site pixel” (i.e. the middle of the spatial subset). This is where a flux tower is located.
Do you need to Know Your to use MODIS?
The results of the analysis of MODIS data within R are illustrated. For this time series analysis demonstration it is not required to know R details, we only use R for some practical demonstration of its great potential. In this exercise we will automatically download MODIS data for specific locations around the world.
Where do I get the NDVI data from?
(1) Download MODIS tiles containing the NDVI information for the appropriate geographic area and point in time. First, go to the website for the USGS EarthExplorer. If you don’t already have an account, you can easily create one here.