t
ıtation
c. Boundary differences
The perimeters of the three enumeration districts had to be
delineated twice, one on the grid superimposed on the B+W
photography and one on the grid superimposed on the CIR
photography. The same line had to be traced twice by hand which
means that different grid cells were left out or included in
the two cases. Such disagreements occurred along the perimeters.
A number of 27 cases were recorded.
2. Real Differences (B)
a. Within groups: B+W assessed as correct and CIR as
in error
These were cases where the cross was representing a land use
value "beyond doubt" on the B+W photography on a "unit" or
"sub unit level" but the identical cross on the CIR photography
showed a different land use. ‚In these cases the B+W had to
be accepted as correct. No such case was recorded.
b. Within groups: CIR assessed as correct and B+W as
in error
These were cases where the cross represented a land use
value "beyond doubt" on the CIR photography on a "unit" or
"sub unit level" according to the criteria established, but
the identical cross on the B+W photography recorded a different
land use. In these cases the CIR was accepted as being correct.
A number of 370 such cases were recorded.
c. Between groups: B4W assessed as correct and CIR as
in errox
In this instance the open space units were easy to describe
but not so easy to allocate to a particular unit in the
notation. The results were that a misclassification occurred
when using the CIR photography. A number of 2 such cases
were recorded.
d. Between groups: CIR assessed as correct and B+W as
in error
These are very significant differences in which the open
space was correctly identified on the CIR and incorrectly
identified on the B+W. A number of 31 such cases were recorded.
e. Field check necessary
In only two cases was it found that the type of open space
could not be identified from either of the two types of
photography.