Copy of the Vision of Britain g_foot table prior to 2016 rebuild.

Table ID:

G_FOOT_2015     (1247943)

Contents:

Copy of the Vision of Britain g_foot table prior to 2016 rebuild.

Approx. number of rows:

83,863

Table type:

Raw Data

Documentation Author:

Humphrey Southall

Sources:

1. The "footprints" table has been built up by the Great Britain Historical GIS Project over many years, so it needs to be treated as primary data.

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Notes:

1. This table has a long and complex history. It was originally constructed in Oracle in 2004, and is the version retained on the development system at Portsmouth so certain corrections made to the production system in Edinburgh were not made to this. A good overview of its contents are provided by this query:
   
   select   im_auth,
               g_unit_type,
               min(util.get_start_year(g_duration)) as start,
               max(util.get_end_year(g_duration)) as end,
               count(*) as freq
   from   gbhdb.g_foot_2015
   group   by im_auth, g_unit_type
   order   by im_auth, g_unit_type;
   
   
2. It contains most of the historical boundaries constructed by the GB Historical GIS project while based at Queen Mary, University of London. Parish boundaries are held only as single-date boundaries for census years, but pre-1911 Registration Districts/Poor Law Unions, and post-1911 Local Government Districts, are held with detailed dates of boundary changes. These cannot be easily reconstructed from other versions of the boundary data, but NB there are known to be errors in these dates.
3. In building the Vision of Britain system, boundaries for modern British units were added, from data provided through the Office of National Statistics. However note:
   • This is a record of 2001 census geography and needs to be updated.
   • As well as the boundaries from ONS, which are very detailed, we have a second set for the same units provided by Danny Dorling (im_auth = 'DD_map'). These are massively generalised, to enable rapid statistical mapping.
   • The existence of these two sets of boundaries for the same 2001 geography is why a series of flags exist identifying which polygons should be used for particular purposes. For most units, all these flags are 'Y', but for the modern census geography they enable software to choose between accuract and speed.
   • These modern boundaries have a start date of year 1, as they are intended to be used for mapping re-districted statical data from the earliest censuses.
4. The table includes boundaries derived from research at Exeter University by Roger Kain and Richard Oliver. These have im_auth = 'Exeter', and should not be used in future systems for copyright reasons.
5. The table was substantially extended in 2007-9 with:
   • Detailed historical boundary data for Estonia and Sweden supplied by their national archives.
   • Boundary data for the modern NUTS units for Europe as a whole downloaded from EUROSTAT, and also EUROSTAT's modern international boundaries for the whole world.
   • Historical international boundaries for Europe constructed from diverse sources by Katie Dooley, employed at Portsmoutth with funding from the EU FP6 QVIZ project.
   • Constituency boundaries for Britain constructed at Portsmouth, mainly by Decio Battaglia and Paula Aucott, with funding from JISC.

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Checking:

1. This table is known to have many problems so should be used with care. Values of g_unit, g_unit_type, im_auth and ul_auth do not necessarily exist in the relevant tables of the current AUO.

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Indices:

Index	Type	Column(s) indexed
g_foot_2015_pkey	Primary key	g_seq
g_foot_2015_g_foot_ertslcc_idx		g_foot_ertslcc
g_foot_2015_g_foot_idx		g_foot
g_foot_2015_g_unit_g_seq_idx	Unique	g_unit, g_seq

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Constraints:

The table has the following associated constraints:

Constraint	Type	Details
g_foot_2015_pkey	Primary Key	See details above for primary key index
enforce_dims_g_foot	Check	((st_ndims(g_foot) = 2))
enforce_dims_g_foot_ertslcc	Check	((st_ndims(g_foot_ertslcc) = 2))
enforce_geotype_g_foot	Check	(((geometrytype(g_foot) = 'MULTIPOLYGON'::text) OR (g_foot IS NULL)))
enforce_geotype_g_foot_ertslcc	Check	(((geometrytype(g_foot_ertslcc) = 'MULTIPOLYGON'::text) OR (g_foot_ertslcc IS NULL)))
enforce_srid_g_foot	Check	((st_srid(g_foot) = 4326))
enforce_srid_g_foot_ertslcc	Check	((st_srid(g_foot_ertslcc) = 3034))

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Columns within table:

Column	Type	Contents
packed_dur	Text string (max.len.=259).	This holds or held a representation of one of our user-defined date objects held as a simple text string; used in moving these data across from Oracle in 2009.
im_auth	Text string (max.len.=259).	Immediate authority for polygon. Unlike created_by this is not null, so it is the best source of information on where the polygon comes from, but the sources identified here are a mix of paper sources and downloads, and the authority GBHGIS is common. NB this column contains authrity identifiers, notably for Parliamentary Boundary Commission Reports, which do not exist in auo.g_authority.
im_note	Text string (max.len.=259).	Additional detail for immediate authority.
ul_auth	Text string (max.len.=259).	Ultimate authority for polygon.
ul_note	Text string (max.len.=259).	Additional detail for ultimate authority.
created_by	Text string (max.len.=259).	Name of script which originally inserted this row into the table. NB this is null for the majority of rows.
g_seq	Integer number.	Sequence number keeping rows in the order they were loaded in, and providing a primary key.
g_unit	Integer number.	ID of the unit, as defined in the AUO. However, some of these IDs date from the original construction of Vision of Britain in 2004, and either do not exist in the current AUO or link to the wrong units.
g_foot	geometry	Polygon or multi-polygon, held using WGS-84 coordinates.
g_duration	duration_t	Beginning and end dates for polygon, held using our user-defined date objects. In many cases the beginning and end dates are the same, and identify a census year, but for certain polygons these dates should provide a detailed record of boundary changes; see notes.
use_for_md_search	Text string (max.len.=5).	[What is this for?]
g_unit_type	Text string (max.len.=20).	Type of the unit, generally as defined in auo.g_unit_type but including 'STATE' and 'NATION' which have both been replaced by 'COUNTRY'.. NB for some units, especially those in the Exeter GIS, g_unit_type seems to be incorrect.
g_foot_ertslcc	geometry	Polygon or multi-polygon, held using ETRS-89 coordinates. This is the version used by the Vision of Britain site.
use_for_stat_map	Text string (max.len.=8).	Use this version of the polygon for statistical mapping.
use_for_search	Text string (max.len.=8).	Use this version of the polygone for point-in-polygon searching.
use_for_bound_map	Text string (max.len.=8).	Use this version of the polygon for boundary mapping.