Normalized Difference Vegetation Index (NDVI)
NDVI stands for Normalized Difference Vegetation Index and is used to differentiate between surfaces which are covered with live vegetation and those which are not. When monitored over time, NDVI can be used to track and visualize the health and growth rate of live vegetation during the growing season in-order to spot growth issues.
See how the NDVI analysis on circular fields near Al Kiranah in Quatar highlights not just the obvious harvesting and replanting but also non uniform growth not visible when looking just at the satellite image. View these images and analyses in Spottitt here.
Coverage – global
Source Imagery – self-service NDVI analyses can be generated from Landsat 7&8 and Sentinel 2 free open source imagery that goes back to April 1999. The Landsat satellites provide a new image every where in the world every 15 days and Sentinel 2 every 5 days. Through the Spottitt geoportal you can search these sources, select the perfect image (location, date, % cloud and %snow cover) and set your NDVI analysis running. You will be informed by email and notification within Spottitt the moment your analysis is ready.
NDVI analysis resolution – 30m if based on Landsat 7&8 imagery and 10m if based on Sentinel 2 imagery.
Minimum Mapping Unit – 10 pixles. This means that all polygons are 10 pixels or more in size.
Viewing your NDVI anlaysis and source imagery – Interactively via the Spottitt geoportal, no special GIS software required.
Editing your NDVI anlaysis – polygon class allocation and polygon outline editing can be done via the Spottitt geoportal, no special GIS software required.
Standard NDVI anlaysis legend – 11 classes ranging in value from +1 to -1. The higher the value the stronger the health, density and growth of vegetation. Values <0 typically indicate water. 0 to 0.5 equates to non vegetated surfaces and sparse vegetation. 0.6 – 1 equates to vegetation of increasing health density and growth. The no data class refers to areas of the source image that were covered in cloud, cloud shadow or hill shadow and for which no classification can be made because the land cover is obscured, or too dark.
Exporting your NDVI anlaysis and source imagery – all Spottitt anlayses can be downloaded in .shp file format for easy export to GSI software packages and .dxf for export to AutoCAD. Landsat 6&7 and Sentinel 2 source imagery can be downloaded in .tif raster format. You can also export what you see in the Spottitt geoportal with legend for inclusion in reports in many formats including .jpg, .doc, .pdf and more.