Lab 6: Digital Change Detection

Background
The goal of this lab is to develop an image that shows change detection of land surface features over time. First a means of performing a qualitative change detection will be performed, then we will quantify post-classification change detection, and a model will be developed that will map detailed change of land use land cover images over time.
Methods
Part 1: Change detection using Write Function Memory Insertion
The first part of the lab, a Write Function Memory Insertion is utilized. This processes utilizes near infrared bands, when the two images are brought into the Write Function, an output image is produced, and the image has areas highlighted in pinkish red, these are areas that have experienced change. Specifically in this lab, ec_envs1991.img and ec_envs_2011.img were used to perform this change detection.
Part 2: Post-classification comparison change detection  
In this part of the lab a From-to change detection using classified images of the Milwaukee Metropolitan Area for 2001 and 2011 will be utilized to see change over the two time periods. This process required quantifying in hectares, the change that occured in Milwaukee area. A chart is used for this conversionin excel (Table 1). this data will later be used in a model to perform the change. 
A sophisticated model was developed Utilizing the first algorithm which provides a change detection over the ten year period.

Where ΔLUC = From-to change class. IM1= Classified image for date 1. 
IM2= Classified image for date 2.  v1….vn = Class values.
vt = classes not interested in for a particular sub-model 
set{0,1}= mask classes not interested in but highlight interested class. 
1a = From pixel value of interested class. 

1b = To pixel value of interested class. 

Then a model was produced to convert to a change detection image (Figure ?), an either or function is used (Figure ?), and a bitwise function is also used within the model (Figure ?).
Figure ?: Model for performing the change detection.
Figure ?: Either Or function

Figure?: Bitwise Function.




Results
Part 1: Change detection using Write Function Memory Insertion
When performing the Write Function Memory Insertion, a changed image is produced that shows how the false color images over the same eau Claire study are have changed between 1991 and 2011 (Figure ?). This change detection is fairly accurate, and we see most change occuring around river and water features, this is because rivers are constantly changing over time.
Figure ?: This image shows the Write Function Memory Insertion  change detection.
Part 2: Post-classification comparison change detection 
The map below shows the 5 change trajectory classes over the 2001 to 2011 period. 


Sources
Homer, C.G., Dewitz, J., Fry, J., Coan, M., Hossain, N., Larson, C.,
Herold, N., McKerrow, A., VanDriel, J.N., and Wickham, J. 2007.
Completion of the 2001 National Land Cover Database for the
Conterminous United States. Photogrammetric Engineering and
Remote Sensing, Vol. 73, No. 4, pp 337-341.


Homer, C.G., Dewitz, J.A., Yang, L., Jin, S., Danielson, P., Xian, G.,
Coulston, J., Herold, N.D., Wickham, J.D., and Megown, K., 2015,
Completion of the 2011 National Land Cover Database for the
conterminous United States-Representing a decade of land cover
change information. Photogrammetric Engineering and Remote
Sensing, v. 81, no. 5, p. 345-354

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