Geoscience Reference

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Figure3.3(a))andanintervaloftimewiththeTF“inearlyJanuary2001”(see TF
#9
,

Figure 3.3(b)).

a)

b)

Figure 3.3. Example of an application of tiling: a) spatial features on a

communal administrative tiling and b) temporal features on a monthly

calendar tiling - illustration taken and then adapted from [PAL 10d, PAL 11]

Standardization by tiling will then be performed in two steps: the choice of the

segmentation for each dimension and then the representation of the information of

each first-level index in this tile-based grid. Thus, the spatial information needs a

regular or administrative tiling (commune, county, etc.) of the zone covered by the

document repository and a calculation of intersections of the SFs of the index and of

this tiling. Similarly, temporal standardization needs a regular or calendar tiling (day,

week,month,etc.)oftheperiodcoveredbythedocumentrepositoryandacalculation

of intersections of the TFs of the index and of this tiling.

Figure 3.3(a) illustrates the communal administrative tiling of the zone. The SF

“near Bayonne” (SF
#5
) is in intersection with seven tiles (communes surrounding

Bayonne).Similarly,Figure3.3(b)illustratesthemonthlycalendartilingoftheperiod.

The TF “in early January 2001” (TF
#9
) is included in the T
9
tile (month of January

2001).

The index excerpt presented in Table 3.1 illustrates the application of temporal

tiling described in Figure 3.3(b): we can find the corresponding frequencies for the

tiles T
1
, T
2
,...,T
n
.For example, TF
#6
is in intersection with four tiles (T
2
, T
3
, T
4
,

T
5
); the binary frequency relative to each of these tiles will be increased by 1. As for

the tile T
3
, it is in intersection with two TFs (TF
#2
and TF
#6
); consequently, it will

haveastandardweightof2.Theproportionalfrequencytakesintoaccountthesurface

ofcoveragecorrespondingtotherepresentationofafeatureandtothatofatile.Italso

takes into account the scale of the feature with respect to that of the tile. For example,

such a calculation will determine a proportional frequency of 1.08 for the application

of TF
#2
and TF
#6
on the tile T
3
.

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