Change detection in a specific class

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11-28-2014 05:30 AM
SadroddinAlavipanah1
New Contributor II

Hi :)

 

I have two classified images of different years. I am interested in mapping the gain and lost of my study area. So change detection tool is the tool, right? More specific to say, I would like to ask ArcGIS (10.2) to show me those pixels which have been changed. I have three classes of Mangrove Forest (with value of 1), Upland-forest (value=2) and non-forest (value=3). I would like to see the changes in just of my classes.

 

Year 1994

1994.JPG

 

 

 

Year  2000

2000.JPG

 

 

I appreciate any help of yours.

 

Cheers,

Sadra

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XanderBakker
Esri Esteemed Contributor

Statistically the amount of a class changed can be derived from the count fields in both attributes tables shown in your screen shots.

If you want to see which pixels have changed you can use the "Not Equal" tool (in Spatial Analyst Tools\Math\Logical). This will generate a result where all pixels that have changed will have value 1 and the ones that remained the same will have value 0.

Maybe you are interested to see the change in each class (which amount of non-forest changed to upland-forest or mangrove). In that case you can use the "Combine" tool (in Spatial Analyst Tools\Local) which will produce a raster that contains the a unique value for each combination of input and output values. Using the attribute table of the result will provide you the information on switched between classes and the raster itself allows you to identify each combination spatially.

Kind regards, Xander

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