change detection |ndvi
TRANSCRIPT
The values are representative of increasesand decreases of NDVI values in 10%increments. An increase or decrease ofless than 10% is considered to be an areaof "no change". The areas of increaseare shown in shades of green indicatingan increase in the amount of vegetationand the areas of decrease are shownin shades of brown indicating a decreasein the amount of vegetation.
Value Distribution:
This subset area of the coastal corridorincludes the city of Biloxi, the Sand HillCrane Refuge, and the mouth of thePascagoula River.
Location:
Change Detection
Imagery:
Projection:
Datum:
Landsat ThematicMapper (LS 5, 7)
Mississippi TransverseMercator (MSTM)
North AmericanDatum of 1983
Mississippi I-10 Coastal Corridor Change inNormalized Difference Vegetation Index
%
CONTACT INFORMATION:
Copyright © 2001 CGTC, Mississippi State University
Dr. Roger L. KingNCRST-E Consortium Director(662) [email protected]
Dr. Charles O'HaraNCRST-E Consortium Coordinator(662) [email protected]
Map prepared by John Cartwright, Computational GIS/RS Lab
The calculation of Normalized Difference VegetationIndices (NDVI's) can be very useful in the generationof a land-use/land-cover classification. NDVI's canprovide useful information about the health and amountof vegetative cover across the landscape. The comparisonof NDVI's can show seasonal variations within vegetativecover, helping to distinguish between deciduous andevergreen forest types. Comparisons can also be usedto show variations of vegetative cover over longertemporal periods.
The magnitude of change from multiple NDVI's can betabulated in various ways. One such way would be to lookat the raw difference in the NDVI values from year oneto year two. However, looking at the percent changefrom year one to year two could be more useful in termsof the overall assessment of change within an area.
The upper image depicts the percent change from February1991 to February 2000 based on the calculated NDVI values.The percent change was calculated for increase or decreasein NDVI values normalized to the value of global maximumincrease or decrease between the two images. Increasesindicate the addition of vegetation and decreases indicatethe removal of vegetation. Prominent areas of increasemight indicate the regeneration of a forest after an earlierharvesting and areas of decrease might indicate the removalof vegetative cover for land development.
> 40%30 - 40%20 - 30%10 - 20%
-10 - -20%-20 - -30%-30 - -40%> -40%
No Change
EXPLANATIONAmount of Change in NDVI Values |NDVI
Normalized Difference Vegetation Index from Landsatsatellite imagery acquired on February 14, 1991
Normalized Difference Vegetation Index from Landsatsatellite imagery acquired on February 15, 2000
Scale:Upper PanelLower Panels
1: 175,0001: 425,000