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Last Post 10 Sep 2018 02:20 PM by  MariM
Confusion Matrix with ROIs
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Vahid Rashidian



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07 Sep 2018 02:25 PM
    Hi Everyone,
    I have several ROIs that represent different objects on the ground and in every ROI I have same number of pixels. But when I generate the confusion matrix, the Envi multiply the number of pixels in each ROI by 4. For instance, if I have a ground truth ROI that represent water and comprised of 10 pixels, I will see the "water" class in confusion matrix with total number of 40. I have tried many times and each time, Envi multiply it by 4 ( even when you have only 1 pixel in the ROI, it will show up as 4 in the confusion matrix).
    Does any one know what is going on with ENVI and how does it generate the confusion matrix with ROIs?

    Thanks.

    MariM



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    10 Sep 2018 02:20 PM
    Are you using the Confusion Matrix using Ground Truth ROIs?
    Are you using ENVI or ENVI Classic?
    Sometimes more than one instance of an ROI can be open and then you could possibly get duplicate ROI pixel locations. I would make sure your ground truth ROIs are open 'new' and then calculate some statistics on them to make sure you know the number of pixels in each class.
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