What exactly does ratio to scene evaluate when used in a condition of assign class?
I am trying to understand exactly what a Ratio to scene means.
I am trying to interpret a preexisting rule set. It uses a 'Relational Feature' in Feature View which I can see in Object Features > Layer values > To scene > Ratio to scene. In a process, this Relational Feature is then used in an evaluation within a condition of the assign class algorithm (Condition: Ratio to scene B7_WV <= 1.1). I am trying to understand exactly what that condition is evaluating. I assume that for each object it is comparing the mean value for band 7 and then comparing that to a scene value for band 7 (which I am guessing is the mean band 7 value of all objects within the scene).
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You are absolutely right, the features compare each object with the mean of the scene. If the value is 1, the object has the same "brightness" as the whole scene (you can test the feature with a large object, created with a chessboard 999999, it will have value 1).
In your rule set example, the rule set developer assigned a class to an object if it is darker than the mean of the scene (with a tolerance of 10%, that's why she/he used 1,1).
Please let me know if you have any questions.