NTDB & NTMS Specifications (250K & 100K)
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Updated: 11 December 2006
The Feature Type dictionary layout
1. Introduction
This Feature Type Dictionary layout page provides an explanation of the structure of an entry in Feature Type Dictionary. It details each aspect of the entry including, where applicable, how and in what context the field should be used.
In addition, at the end of this page is a sample entry. This entry shows the location of each field and may, when applicable, provides some examples of how they could be populated.
2. Structure of an Entry
| Field |
Explanation |
| Scales |
This gives the scales to which the feature type applies. Some feature types are only used for 1:100 000 or 1:250 000 mapping and Geodatabase, others are used at both scales. |
| Feature Type |
The feature type classification to which the entry relates. |
| Feature Class |
The feature class in which the feature type classification is contained |
| Feature Dataset |
The feature dataset in which the feature type classification is contained. |
| Geometry Type |
This is the spatial object type; Polygon, Line, Point or Annotation |
| Definition |
The definition which applies to the feature type.
Classification of features is to be based on their match to the feature type definition and not their name. For example, an area named Williams Swamp may need to be classified as Land Subject to Inundation when it meets the definition of a Land Subject To Inundation but not the definition of a Swamp. |
| Minimum Size for Inclusion |
The size criteria for inclusion. Length Criteria may apply to linear features such as roads, watercourses and canal lines. Area criteria may apply to polygons or in certain cases to point features, such as buildings, to minimise capture of features of little value (e.g. garden sheds).
Minimum sizes for inclusion have been represented not only for 1:100 000 and 1:250 000 scales but also for 1:25 000 to cater for the increasing large scale capture work being conducted at present which will feed into the TOPO100K and TOPO250K NTDBs.
All newly captured features obtained from any revision source material/imagery must comply with the size criteria as stated in these specifications.
Length and area criteria is defined using metres on the ground.
Length criteria will not apply to features that join two or more features in the same network at each end.
The minimum area & length indicated for a polygon and linear features inclusion respectively, will apply to the full size of the feature in the real world.
This means that in the case of Built Up Area & Island feature types as well as the Reserves feature class where multipart polygons exist, the size criteria will apply to total area formed by its component parts.
Also, when capturing new features within a work package extent, if the portion within the work package is smaller then the minimum size for inclusion but it is known that the full extent of the feature in the real world meets or exceeds the size criteria, then the portion within the work package should be captured.
Further clarifications to the use of the minimum size for inclusion criteria may be documented within the Geodatabase Rules for each entry. |
| Data attributes |
The data attributes define the applicable fields in the geodatabase model for each feature type and the acceptable values. When an item appears in the feature class table but is not documented in the feature type data attributes list, it means that it is not applicable to that feature type and should not be populated.
For each field, a field descriptor eg FEATURE RELIABILITY DATE is followed by the field code in round brackets e.g. (FEATURERELIABILITY) and the data type in square brackets e.g. [Date; Standard Format; No] and a brief description e.g. The reliability date of the spatial object. This information may be followed by legal entries used in the field and any qualifiers as required.
The data type definitions are based on standard ArcGIS data types. The following are examples of the definitions used and their meaning.
[Date; Yes; 0; 0; 36; Pop_Req] This means the field is a date field using standard ArcGIS format with the yes indicating null values are allowed. It has a precision of 0, a scale of 0 and a length of 36. Item must always be populated with a value.
[Double; Yes; 18; 11; Pop_Req] means a numeric field, with the yes indicating it allows null values. It has a precision of 18 and a scale of 11.Item must always be populated with a value.
[Float; Yes; 6; 2; Pop_Req] means a numeric field, with the yes indicating is allow null values. It has a precision of 6 and a scale of 2.Item must always be populated with a value.
[Long Integer; No; 6; Pop_Req] means a numeric field with no allowable null values and a precision of 6.Item must always be populated with a value.
[Short Integer; Yes; 4; Pop_Req] means a numeric field, with allowable null values and a precision of 4.Item must always be populated with a value.
[String; No; 1000; Pop_Req] means a character field, with no allowable null values and a length of 1000 characters available.Item must always be populated with a value.
In all of the above examples, the last entry was Pop_Req. This is one of numerous options for the status of required population of an item. The complete list and associated definitions are as below:
Pop_Req (Population Required): All features must have this item populated. If information is not available to complete this item's entries, either from the supplied base material/digital data or authorised source material, then an Action Request to GA should be generated.
Pop_Aut (Population Automatic):Population of this item is conducted by automatic means on entry to GA's NTDB. Producers should not alter or add or delete values within this item in any way during production processes without authorisation from GA.
Pop_Wk (Population Where Known):All features must have this item populated where information is available in either the supplied base material/digital data or authorised source material provided by GA. If information is not available no Action Request is required unless leaving the field blank would cause a logical inconsistency.
Pop_Dep (Population Dependant): Population of this item, for each feature type, is dependant on specific rules within the brief description following the data type entry.
Planimetric & Elevation accuracy is given in metres. The accuracy for 1:25 000 is before the first slash, the accuracy for 1:100 000 is between the slashes and the accuracy for 1:250 000 is after the last slash. Where the accuracy is not applicable for a spatial object at a particular scale this is indicated by a dash (-). When an accuracy requirement is not stated in work instructions this is the minimum planimetric and elevation accuracy that must be met for capture of this feature. Where features are captured more precisely than the minimum planimetric and elevation accuracies stated in the specifications this may be indicated by a more reflective value entered into the relevant field. (e.g. The planimetric accuracy for road in the specifications is stated as 100m at 1:250 000 but a road was captured to within 20m of its centreline position on imagery. The imagery has a known ground control error of 15m and therefore the roads is within a maximum of 35m of its ground position. The value of 35 may be used in the planimetric accuracy field, for that feature, in precedence to the value of 100. ) (see Section 1 3.7 Positional Accuracy and Section 1 3.6 Feature Level Metadata for more information) |
| Geodatabase Rules |
The geodatabase rules section includes any additional selection criteria and any other notes on usage which apply to the representation/capture of the feature type data entry into the applicable geodatabase. This section will be blank if there are no specific notes not covered by other sections. |
| Inter-Feature Relationship Rules - Internal to Associated Dataset |
The section specifies relationships between the designated feature type and other feature type entities within the same dataset. |
| Inter-Feature Relationship Rules - External to Associated Dataset |
The section specifies relationships between the designated feature type and other feature type entities not within the same dataset. |
| Map Rules |
The map section gives information specific to the use of the feature type on the map. This section will be blank if there are no specific notes or when information from the feature type is not used on the map. Map rules do not influence how information is to be captured within the geodatabases. |
| Related features |
Feature types which have a relationship with this feature type.
When all feature types in a single feature class have a relationship with the designated feature type, the feature class may be specified instead of the individual types but in this case it will be noted as such. E.g WaterbodyBoundaries (Feature Class). |
| Related chapters |
Chapters in the specification which include information relevant to this feature type. |
| Related Products |
Products produced by GEOSCIENCE AUSTRALIA which may use the feature type. E.g. 250K NATMAP. (This field is currently unpopulated) |
| Note |
Additional Note, generally a disclaimer of some kind. |
3. Sample Entry
| Scales |
1:250 000
&
1:100 000
|
Feature Type
Feature Class
Feature Dataset
Geometry Type
Definition
Minimum Size for Inclusion
| Criterion |
1:25 000 |
1:100 000 |
1:250 000 |
| Area (sq m) |
|
|
|
| Length (m) |
125 |
500 |
1250 |
Data Attributes
Examples:
CLASSIFICATION
(CLASS)
[Text; 40; No; Pop_Req]
The entities classification or status;
Applicable field entries
Dual Carriageway
Principal Road
Secondary Road
Minor Road
Track
NATIONAL ROUTE NUMBER
(NRN)
[Text; 12; Yes; Pop_Wk]
The national route number/s assigned to the road ( if multiple numbers, delimited by a minus sign). Alpha characters in this field are to be in upper case.
FEATURE RELIABILITY DATE
(FEATURERELIABILITY)
[Date; Standard Format; Yes; Pop_Req]
The reliability date of the spatial object; Date to be adjusted only during spatial change or verification of an existing feature location or the capture of a new feature (see Section 1 Chapter 3.6);
Most Recent Reliability Date of Base Material/Digital Data used for Spatial Verification
PLANIMETRIC ACCURACY
(PLANIMETRICACCURACY)
[Short Integer; 4; No; Pop_Req]
The standard deviation of the horizontal positional accuracy.
10 / 40 / 100
FEATURE WIDTH
(FEATUREWIDTH)
[Double; 8; Yes; Pop_Dep]
Feature width is only used for roads under construction (symbol 252). All other roads will have a feature width of ‘0’. The width of symbol 252 reflects the road classification, the following values will be used:
Feature width; Road class;
0.9 - Dual carriageway
0.9 - Principal road
0.6 - Secondary road
0.4 - Minor road
0.2 - Vehicular track
Geodatabase Rules
Examples:
At 1:100 000 size and any other selection criteria apply to all feature occurrences. An exception will be minor roads in built up areas which will be treated as per the rules stated in Inter-Feature Relationship Rules - External.
At 1:250 000 size and any other selection criteria apply to new feature occurrences. All feature occurrences existing in the TOPO250K NTDB will be retained unless there is clear evidence they no longer exist. An exception will be minor roads in built up areas which will be treated as per the rules stated in Inter-Feature Relationship Rules - External.
Classifications are:
Dual carriageway - Divided Highway, Freeway, Tollway, or other major roads with separated carriageways in opposite directions.
Principal Road: - Highways, major through routes and major connecting roads.
Secondary road: - Connecting roads that provide a connection between major through routes and/or major connecting roads, or connections between regional centres.
Minor road: - All other roads which form part of the public roads system between Principal roads and Secondary roads.
Vehicle tracks: - Public or private roadways of minimum or no construction which are not necessarily maintained.
Roads will not be added only from interpretation of the imagery. However obvious road realignments may be captured when significant.
Inter-Feature Relationship Rules - Internal to Associated Dataset
Examples:
Where the foot track is associated with or uses a section of road it should be made coincident with that portion of the road. A vertex on the road should exist at the exact location of the entry and exit points of the foot track.
Inter-Feature Relationship Rules - External to Associated Dataset
Examples:
Roads cannot overlap;
Sea, Flood Irrigation Storage, Town Rural Storage, Lake perennial, Canal Areas, Watercourse Area perennial.
Map Rules
Examples:
At 1:100 000 naming of minor roads and vehicular tracks should give preference to features which consititute through routes and/or lead to cultural or natural features. Density of detail should determine the number of names shown. If a previous edition 1:100 000 map has been supplied this should be used as a guide for which roads are to be named in the new product.
Roads whose position is questionable will be labelled ‘position approximate’.
The road subclass ‘Dual Carriageway’ will mask all other road subclasses (e.g. ‘Principle Road’, ’Secondary Road’, ’Minor Road’, ’Track’).
Related Features
Examples:
Built Up Area, Cemetery Area, RecreationAreas (Feature Class), Ferry Route Line, Ford Line, Ford Point, Gate, Distance Indicator, Gorge, Pass, Road Junction, Place Name, Populated Place
Related Chapters
Examples:
Section 2 chapter 2.2.3
Section 3 chapters 3.2.4, 5.8, 5.11.2, 6.5.3 and 6.7
Appendix C
Related Products
Note: See disclaimer in Appendix A Chapter 1.2 Use of Feature Type Dictionary - Structure of an Entry regarding Related features,chapters & products.
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