Feature type attributes

OS_TOPO_TOID

Unique feature identifier of the topographicArea building polygon taken from OS MasterMap Topography Layer.

• Type: CharacterString

• Length: 20

• Multiplicity: [1]

OS_TOPO_TOID_VERSION

The version number of the TOID for which the height values have been calculated.

• Type: Integer

• Length: 3

• Multiplicity: [1]

BHA_ProcessDate

The date that the Building Height Attribute values were calculated for the given OS_TOPO_TOID. Dates will follow the structure YYYY-MM-DD.

• Type: Date

• Length: 10

• Multiplicity: [1]

TileRef

The 5km² tile reference within which the Building Height Attribute is located.

• Type: CharacterString

• Length: 6

• Multiplicity: [1]

AbsHMin

AbsHMin is the absolute minimum height of the intersection of the external building walls and the underlying ground surface.

• Type: Real

• Length: 4.1

• Multiplicity: [1]

AbsH2

AbsH2 is the absolute height of the base of the roof, that is, where the roof intersects the principal part of the building. The principal part of the building is defined as the main structure.

• Type: Real

• Length: 4.1

• Multiplicity: [0..1]

AbsHMax

AbsHMax is the absolute height of the highest point on the building and can include any structure, such as chimneys, plant housings and machinery.

• Type: Real

• Length: 4.1

• Multiplicity: [0..1]

RelH2

RelH2 = AbsH2 – AbsHMin. RelH2 is the relative building height from the base of the building (AbsHMin) to the height of the base of the roof (AbsH2).

• Type: Real

• Length: 4.1

• Multiplicity: [0..1]

RelHMax

RelHMax = AbsHMax – AbsHMin. RelHMax is the relative building height from the base of the building (AbsHMin) to the height of the highest point on the building (AbsHMax).

• Type: Real

• Length: 4.1

• Multiplicity: [0..1]

BHA_Conf

A qualitative assessment of the confidence of the height statistics for each topographicArea building polygon.

• Type: BHA_ConfValue

• Length: 2

• Multiplicity: [1]

This section describes the single feature type that makes up the OS MasterMap Topography Layer – Building Height Attribute product. The Building Height Attribute feature type has 10 attributes. The following information is given about each attribute:

Attribute Name and Definition

The name of the attribute and what it is describing.

Attribute Type

The nature of the attribute. The following values may occur:

Multiplicity

Describes how many times this element is expected to be populated in the data. An attribute may be optional or mandatory within the product as denoted by the following:

• [1] indicates that the attribute is mandatory and can only occur once.

• [0..1] indicates that the attribute is optional; if present, it only occurs once.