Some question about translation matrix?

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Now i have two images ,and i have already matched some sift feature in the two .I calculate the essential matrix and use function to get the R and T .Then the result seems that the value of T is always between -1 and 1,can you tell me what the value means ? Actually, I think that T represents the vector between camera coordinate's origin( the norm of this vector equals 1). But does the value mean that wherever the two images is taken, the distance is 1 ?

C:\fakepath\1.png C:\fakepath\2.png