 If the essential matrix formula_2 is multiplied by a non-zero scalar, the result is again an essential matrix which defines exactly the same constraint as formula_2 does.This means that formula_2 can be seen as an element of a projective space, that is, two such matrices are considered equivalent if one is a non-zero scalar multiplication of the other.This is a relevant position, for example, if formula_2 is estimated from image data.