Geoscience Reference
In-Depth Information
List of
id
TF
Cumulated binary
frequency (TF//tile)
Cumulated proportional frequency
(TF//tile)
id
t
T
1
[]
0
0
T
2
[TF
#6
]
1
0.21
T
3
[TF
#2
; TF
#6
]
2
1.08
T
4
[TF
#3
; TF
#6
]
2
1.98
...
Table 3.1. Example of a temporal tile-based index -
taken and then adapted from [PAL 10d]
These indexing strategies allow us to propose several indexes based on spatial and
calendar tilings: spatial indexes whose segmentations are of district, city, township,
county,region,countrylevelandaswellascalendarindexeswhosesegmentationsare
of day, week, month, season, year and century level. In a GIR context, these indexes
thenallowasearchenginetobrowsetheindexmostadaptedtothespatialandcalendar
range of the query.
3.4.1.2. Standardization by tiling: formalization of the approach
This type of standardization consists of using a tiling to describe the spatial or
temporal representations stored in the first-level indexes generated by the PIV
process flows. This approach is a form of discretization, for example it associates a
temporal object of the calendar domain with a temporal tile corresponding to a
particular segmentation of the same space.
In a more formal way (equation [3.1]), a domain T included in the space R
n
corresponds to the domain
1
O included in the space R
n
2
. The domain O is composed
of a set of objects O
1
,...,O
p
(the features of the first-level index), and the domain
T is composed of the union of m subspaces (the tiles of the standardized index). For
each subspace (T
i
) of T in intersection with one or more objects (O
j
) of O, we retain
the number of intersections (N
T
i
).
O ⊆ R
n
−→ T ⊆ R
n
O = { O
1
,O
2
,O
3
,...,O
p
}
T=
i=1
T
i
N
T
i
= Card({T
i
| T
i
∩ O
j
= ∅,∀j =1,...,p})
with Card(x)the cardinality of x
[3.1]
1 Adomainisafiniteorinfinitesetofvalues.Itisrepresentedbyalistofelementsoranecessary
andsufficientconditionofbelonging-thedomainofBooleans: {0,1},thedomainofthefingers
of the hand: {thumb, index finger, middle finger, ring finger, pinky}, the calendar domain.
2 This superset refers to spaces of dimension 1, 2 or more.
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