How to calculate NDVI from MODIS satellite data?

How to calculate NDVI from MODIS satellite data?

In this exercise, you will use ArcGIS’ Image Analysis tool to compute Normalized Difference Vegetation Index (NDVI) values for the Howland Forest area (located in Maine) using MODIS (Moderate-Resolution Imaging Spectroradiometer) satellite data. You will then use Spatial Analyst to compute zonal statistics for an area of interest.

What is the normalized difference vegetation index ( NDVI )?

The Normalized Difference Vegetation Index (NDVI) is a quantitative index of greenness ranging from 0-1, where 0 represents minimal or no greenness and 1 represents maximum greenness. NDVI is often used for a quantitate proxy measure of vegetation health, cover and phenology (life cycle stage) over large areas.

How to calculate the NDVI in raster data?

To calculate NDVI, you use the following formula where NIR is near infrared light and red represents red light. For your raster data, you will take the reflectance value in the red and near infrared bands to calculate the index.

What are the bands of NDVI in MODIS?

Only bands 1and 2(representing the red and near-infrared parts of the spectrum) are present in this map project for each month of the year 2008. The bands are grouped by month. In this exercise you will use bands 1 and 2 to compute the NDVI values for each pixel in the MODIS rasters.

How to export NDVI from Google Earth Engine?

I generated a Lansat 5 image NDVI in a rectangle of interest in Google Earth Engine. After that, I tried to export the image to my Google Drive, but the final result does not load the usual values of an NDVI (-1 to +1), as is usually done in a GIS program (QGIS, ArcGIS, etc.). The DN has a single value (attached image).

How to export a time series of NDVI layers?

According to the different shape of the polygon: try to clip your image collection to your polygon boundaries before exporting. However, GEE will always export the image with the bounding box of the polygon where NoData values are assigned to the areas outside the polygon.

How to calculate the NDVI for green vegetation?

The NDVI is computed as follows: where RNIRis the reflectance in the near infrared part of the spectrum, and Rredis reflectance in the red part of the spectrum. The value of the index ranges from -1 to 1. A common range for green vegetation is 0.2 to 0.8. Contents Step 1:        Open the map document2

What is the spatial resolution of MODIS VI?

The MODIS VI products are currently produced at 250 m, 500 m, 1 km and a special 0.05 deg. spatial resolutions. For data processing purposes, MODIS VIs are generated in square tile units that are approximately 1200-by-1200 km (at the equator), and mapped in the Sinusoidal (SIN) grid projection (equal area projection).

What are the dimensions of the MODIS vegetation index?

The gridded vegetation indices include quality assurance (QA) flags with thematic information about the quality of the VI product and input data. The MODIS VI products are currently produced at 250 m, 500 m, 1 km and a special 0.05 deg. spatial resolutions.

How are the MODIS vis calculated in Excel?

For data processing purposes, MODIS VIs are generated in square tile units that are approximately 1200-by-1200 km (at the equator), and mapped in the Sinusoidal (SIN) grid projection (equal area projection). Only tiles containing land features are processed.

How is the vegetation index of MODIS used?

MODIS vegetation indices, produced on 16-day intervals and at multiple spatial resolutions, provide consistent spatial and temporal comparisons of vegetation canopy greenness, a composite property of leaf area, chlorophyll and canopy structure.

Why are the MODIS layers in a raster format?

All 12 MODIS group layers in your map document are in a raster data format, yet they don’t seem to follow an orthogonal grid of cells that you might be accustomed to seeing. This is because the MODIS data were provided to us in a Sinusoidalprojection which distorts shape in our area of interest.