Mike Bobbitt & Associates

NDVI Overview

A Normalized Difference Vegetation Index (NDVI) image is one of the powerful mapping and GIS services that Mike Bobbitt & Associates (in coordination with Grayhawk Airborne Imaging and Vine View) offers their clients. An NDVI is a very economic way to give the grower a picture of the vigor variations across the vineyard and is used for valuable analysis including:

- Identifying and locating variations in vine vigor

- Developing better field sampling plans

- Designing differential harvesting plans

- Adjusting irrigation schedules and irrigation breaks

- Locating frost damaged areas (less growth)

The NDVI measures the infrared reflectiveness of the vegetation, resulting in an indication of vigor relative to other plants in the image. This data can either be collected for use in Relative or for a calibrated (or absolute) NDVIs. The results of these measurements leave each pixel with an NDVI value between -1.0 and +1.0. This image then displays the values classified into a number of color scales dependent on the selected format.

The imagery can be collected and processed in two ways.

The Relative NDVI takes the highest and lowest NDVI value for the entire area and displays this difference in 8-color categories. This gives a good indication of vigor relative to other vines in the image and for change in uniformity over time.

The newer, Calibrated NDVI approach removes atmospheric errors to give absolute NDVI values. This richer data allows for greater analysis for the vineyard. Besides giving a vineyard a better view of the true level of vigor, it allows for more precise comparisons in vigor over time and potential comparisons with similar vines from one vineyard to another.

For current MB&Assoc. clients this service involves registering the NDVI with existing vineyard data and for new customers a map of the vineyard will also be created. Our deliverables include a georefenced map of the vineyard perimeter overlaying the NDVI raster image in both soft and hard copy. In addition, all GPS and GIS data that has been processed for this project is delivered to our clients.