LANDGATE’S TOPOGRAPHIC GEODATABASE (TGDB) ROADS Presentation 20th May 2010 Marty Stamatis.

LANDGATE’S TOPOGRAPHIC GEODATABASE (TGDB)

ROADS Presentation

20th May 2010

Marty Stamatis

www.landgate.wa.gov.au

• Landgate’s Topographic Database / Data Model

• Spatial Topology

• Geodatabase Concepts

• Incremental Update Management

• Geodatabase Tableso Nameso Metadata

• Roads Data Modelo Feature Classeso Sub Typeso Domains

• Sample Roads Data (Attributes)

• Roads Data Dictionary

• Topographic Database Extracts (Roads)o Fullo Incremental

• Coordinate Systems and Data Formats

Presentation Overview


• Landgate’s Topographic DatabaseThe Enterprise Database has two feature datasets:o Medium-scale - Feature Dataset: Topography, with schema names of TPO and TPRo Large-scale - Feature Dataset: Topography, with schema names of TPO_LS and TPR_LS

• This presentation will focus on the Medium-scale dataset

• The Data Model comprises 4 themes:o Ground Surface (landforms, contours, spot heights etc.)o Cultural (man made features)o Hydrography (streams, water bodies etc.)o Transport (road, rail, air, sea, and related features)

Introduction


Topographic Geodatabase – Data Model


Topographic Geodatabase – Roads Layers (Symbolised)


Landgate’s Geodatabase Spatial Topology for Roads

Connectivity is defined through arc-node topology. In the arc-node data structure, an arc is defined by two endpoints: the from-node indicating where the arc begins and a to-node indicating where it ends

Nodes exist at every intersection, except:• at overpasses and• at intersections of an underground road and ground level road.


• Persistent Identifier

• GlobalID

• Incremental Update

• DateFeatureCreated

• DateFeatureModified

• DateFeatureRetired

• Feature Level Metadata

• MetadataID

• Names are not included in the Geodatabase There is a linkage to the GEONOMA - Geographic Names Register.

• NameID (in the TGDB)

• Feature_Number (in the FeatureNames table – mirror of the GEONOMA)

• The use of “magic” numbers

• -99 (Unknown)

• -98 (Not Applicable)

Important Geodatabase Concepts


What is a Persistent Identifier, a “GlobalID” and a “GUID”?

The “Persistent Identifier” is stored in Landgate’s enterprise database against each feature. It is a unique identifier that remains associated with a feature for the life of that feature. It will not change as a result of minor maintenance operations; for example, a feature will retain its current ID if the digitised co-ordinates describing its geometry are replaced by more accurate values, or the feature's attributes are changed. The “GlobalID” field is the persistent identifier.

Global ID and GUID (Global Unique Identifier) are ESRI field data types that store GUID values which are a 36 character sequence of hexadecimal digits enclosed in curly braces e.g. {6B29FC40-CA47-1067-B31D-00DD010662DA}.

GUID values are used to uniquely identify each feature within and across geodatabases.

Global ID field values are automatically populated and maintained by ArcGIS, this differs to GUID field values which must be manually attributed. Global IDs are a prerequisite for geodatabase replication, they exist in Landgate’s enterprise database

Note: the “GlobalID” field in data exports to users will have a data type of “GUID”.

Important Geodatabase Concepts


Important Geodatabase Concepts – Incremental Update Management


• FeatureNames Table (mirror of the GEONOMA)

• Feature_Number (primary id / key)

• Geographic_Name (the name)

• various other attributes that may or may not be of any interest to the user (see next slide)

Users should do a “relate” between the spatial data and the FeatureNames table using the “NameID” and the “Feature_Number” fields.

There is one Feature_Number to many LGA/Locality combinations (1:m)

CAUTION: If a “join” is performed the LGA and LOCALITY information may be misleading

• FeatureInstanceMetadata Table

• MetadataID (primary id / key)

There is one metadata table record for many spatial features (1:m)

Users should do a “join” between the spatial data and the FeatureInstanceMetadata table on “MetadataID”.

Important Geodatabase Tables


• FeatureNames Table

• Feature_Number (primary id / key)

• Geographic_Name (the name)

The following attributes are used by Landgate staff when names are assigned in the Topographic Database, they may or may not have any relevance to external users.

• Feature_Class

• FeatureStatus

• Name_Type

• Map_number

• ABS_LGA_Number

• LGA_Name (when using this attribute please refer to the caution note on the previous side)

• Locality (when using this attribute please refer to the caution note on the previous side)

• Longitude

• Latitude

• Easting

• Northing

• MGA_Zone

Important Geodatabase Tables

Refer to the FeatureNames Table Data Dictionary slides for further information.


Important Geodatabase Tables – FeatureNames Table Data Dictionary


FeatureNames Join / Relate Issue

Feature_Number Geographic_Name LGA_Name Locality

100075123 Albany Hwy Victoria Park, Town of East Victoria Park

100075123 Albany Hwy Canning, City of St James

100075123 Albany Hwy Canning, City of Bentley

100075123 Albany Hwy Gosnells, City of Langford

100075123 Albany Hwy



100075123 Albany Hwy Albany, City of Orana

100075123 Albany Hwy Albany, City of Centennial Park

Join – 1: 1 relationshipRelate – 1: m relationship

All road segments between Perth and Albany have a Feature_Number of 10075123 regardless of the LGA and Locality they pass through. A join will link all road segments to the first record in the table, therefore the LGA and Locality may appear incorrect in some instances. The relate will show all table records that reference to the road segment, consequently the user needs to decide which record is appropriate.


FeatureNames Table


Metadata Data Model


Metadata Data Model – Attribute Fields

1. ElevationAccuracy and PlanAccuracy are expressed as a Linear and Circular Map Accuracy Specification value (LMAS & CMAS are approximately twice the value of the Root Mean Square (RMS) value).

2. SpatialReliabilityDate and AttributeReliabilityDate are generally identical and refer to the date of photography from which the information was sourced.

3. Refer to the Medtadata Data Dictionary slides for further information.


Metadata Data Model – Attribute Domains


Metadata Data Model – Data Dictionary


FeatureInstanceMetadata Table


Roads Data Model - Overview


Roads Data Model - Feature Classes

In addition to the above attributes all features have a:

• DateFeatureCreated • GlobalID

• CreatedBy • fcSubType

• DateFeatureModified • AccessLevel

• ModifiedBy • MetadataID

• DateFeatureRetired • FeatureText (set to Null)

• ESRI System attributes – OBJECTID, Shape and Shape_Length


Roads Data Model - Sub Types


Roads Data Model – Sub Types

The RoadSegment feature class has 8 sub-types. Sub-Types are used to group roads that have similar characteristics. This allows better control of attribute assignment and provides the means to enforce specific spatial topology.

Sub Types Description

Connector An artificial line used to connect road features to allow network analysis of transportation systems. Connectors are normally associated with roundabouts.

NameConnector An artificial line used to show the extent of named, surveyed non-constructed roads. These are legacy features; they are not proposed roads.

OnOffRamp A particular type of road segment. A ramp by which one enters/exits a limited-access highway. This particular line feature is permitted to self intersect.

Overpass A particular type of road segment. One that crosses a road segment at a higher level. The two road segments are not split at their intersection.

Road A particular type of road segment. This particular feature can only intersect other road features at nodes (i.e. lines must split at their intersection point).

Roundabout A particular type of road segment. A small circular pattern at the intersection of two or more roads - used as a traffic-calming device.

Track A particular type of road segment. An unimproved road that does not form part of the public communication system, but which provides access to individual properties or areas used for pastoral or industrial purposes. The surface of which may vary from poorly surfaced, to tracks beaten by the passage of vehicles.

UndergroundRoad A particular type of road segment. This particular line feature is NOT permitted to intersect other road features.


Roads Data Model – Sub Types examples

The RoadSegment feature class has 8 sub-types that help enforce spatial topology.


Roads Data Model - Domains


Roads Data Model – Domains and Attributes

1. Most users will find that three tables will give them most of the information required to produce a useful map representation of the roads. These tables are:• MapClassification (the classifications seen in Landgate’s hard copy products (e.g. street directory,

travellers atlas, touring maps, etc.)• RoadSuface (whether a road is sealed or unsealed etc.)• LaneCount (an indication of the number of lanes / width of the road).

2. When trying to separate Roads from Track the user should distinguish categories using SubTypes. The domain entry “Track” in the MapClassification table identifies tracks that are only valid in Landgate’s hard copy map products.

3. The RoadDirection table has not yet been populated.4. Main Roads Western Australia is the source for the MRWAClassification and MRWARoadNumber. 5. RoadCustodian is only provided as a guide and is meant to indicate a responsible asset custodian/manager

. Its value is derived from the MRWAClassification and the MRWARoadNumber.6. User safety is the prime consideration when assigning attributes. For example, if only part of a road

segment is sealed its surface type will be assigned unsealed.7. Refer to the Data Dictionary slides for actual attribute definitions.


Topographic Geodatabase - RoadSegment (Road)


Topographic Geodatabase - RoadSegment (Track)


Topographic Geodatabase - ProposedRoadSegment


Roads Data Dictionary

A road feature has 15 attributes


Roads Data Dictionary


Topographic Geodatabase – Incremental Extracts

• Landgate’s Topographic Database SchemasThe Enterprise Database has two schemaso TPO – holds all the active features. The current state of the topographic data over Western Australia as it exists right now.o TPR – holds the deleted/retired features. Only of use to users that require the incremental update functionality.

• Incremental Update is only available in ESRI Personal (.mdb) or File Geodatabase (.gdb) formats.

o Incremental Update implies Whole of Sate. Changes over an area of interest is not available.o Two datasets are supplied to satisfy an Incremental Update request.

The full dataset extract over the State The incremental changes over the State

Note: areas of interest (subsets of the Topographic Database) can be supplied but not as an “incremental” delivery.


Topographic Geodatabase – Incremental Roads Extract


Topographic Geodatabase - Full Roads Extract


Topographic Geodatabase – Full Roads Extract


Topographic Geodatabase – Full Roads Extract (Deleted Features)


Topographic Geodatabase - Incremental Roads Extract


Topographic Geodatabase - Incremental Roads Extract

Adds, Deletes and Modified layers are provided for each feature class.


• Geodatabase Coordinate Systems

• Latitude and Longitude

• Map Grid Australia (MGA)

• Formats

• Personal Geodatabase (ESRI)

• File Geodatabase (ESRI)

• Shape (ESRI)

• MapInfo (Tab file)

• Design File (V7 and V8)

• DXF and DWG

Geodatabase Export – Coordinate Systems and Data Formats


Geodatabase Export Considerations

• Full GIS functionality, particularly attribution, is only available in ESRI Personal or File Geodatabase formats, ESRI Shapefile and MapInfo Tab file format.

• CAD formats will have a reduced number of attributes and a structure identical to the old Landgate format for conveying attribution (i.e. the use of Level and Colour combinations to convey attribution).

• File size restrictions exist with all formats other than File Geodatabase.

• By default the Personal and File Geodatabase formats provide descriptions (e.g. sealed) along with the domain codes (integer numbers, e.g. 1). This functionality makes the information self-documenting. Other formats are not so user friendly, for example Shapefiles have a restriction on field name size and only show the domain code (see slide “Possible Shapefile format – sample 2”). In order to overcome this problem, Landgate is investigating an alternative Shapefile structure to aid interpretability (see slide “Possible Shapefile format – sample 2”.


Possible Shapefile format – sample 1


Possible Shapefile format – sample 2

Marty Stamatis

Phone: 92737476Mobile: 0403312330Email: [email protected]

LANDGATE’S TOPOGRAPHIC GEODATABASE (TGDB) ROADS Presentation 20th May 2010 Marty Stamatis.

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Transcript of LANDGATE’S TOPOGRAPHIC GEODATABASE (TGDB) ROADS Presentation 20th May 2010 Marty Stamatis.