Table of Contents
Land and Property Information
Talk to LPI about their plans for topographic mapping in NSW
- why are well-used tracks disappearing from maps? (eg Wollangambe tracks)
- are they willing to take corrections/contributions from bushwalkers, and will they incorporate them?
- [are they willing to license the data (not just the raster images) under a CC or similar licence?]
- Garry Taunton
- Team Leader Spatial Services
- Tracie Walker
Privatisation of LPI
NSW Government is investigating the possibility of privatising LPI. Possibility of breaking the organisation down into branches. Need to investigate what the impact on mapping and access to spatial data may be.
Update - 08 Jun 2016
It appears as though LPI will be broken down into three entities, with Titling and Registry Services (TRS) section of LPI privatised.
Thankfully Spatial Services, the entity relevant for mapping and spatial data, seems set to stay under public ownership.
However, the mapping section has already be moved from Prince Albert Rd Sydney, out to Bathurst. No longer can one walk into an LPI building in Sydney to make mapping related enquiries, or to look at aerial images through a set of stereo glasses.
The ending of hard copy topographic maps
From 3rd September 2018, 524 out of their 1,094 titles for the state were only made available in digital form from Spatial Services. By area, this covered about 3/4 of the state.
A notice regarding the change can be found here
Interactive map of 'digital only' maps
By December 2020, all hard copy printing by Spatial Services had ceased and were no longer available for purchase. This extends to supply for resellers such as outdoor or map shops. Current supply of hard copy maps is only available by existing stock on hand of retailers, or where they are printing themselves from the electronic versions.
Geographic Names Board
- why are coordinates only accurate to the nearest minute in AGD66 co-ordinates? 1 minute is around 1.1km of latitude, and 0.93km of longitude (around Sydney). This means that the accuracy is presumably limited to half of that, or say +/-500m in each direction. For example, Mt Cloudmaker is around 500m from its correct position
- AA spoke with GNB Secretariat (Susan Fietz - email@example.com) on the matter (27 April 2016):
- What is on the GNB website is the official name places list
- Updating of the list planned to start within the next few years
- Any corrections are welcome
- AA spoke with the Surveyor General (Narelle Underwood) on the matter (Jan 2017):
- Acknowledged that the current system has its flaws are requires upgrading
- Work is going to be done (timeframe not specified) on “bringing the GNR (Geographic Names Regester) into the 21st century
- Many errors in the listed coordinates are due to the location being recorded in lat/long to the nearest minute but in the top left corner of the grid square, as opposed to the bottom left as convention dictates.
- AA spoke with staff member from GNB on the matter (Apr 2018):
- Acknowledged the issue and the plans for a project to address it
- No funding available in the current political climate
- access to licensed DEM
- if we use OSM data, it needs to be kept separate from other data or otherwise the other data needs to be released under the same licence
- 1:63360 (1 inch:mile)
- 1st edition
- 2nd edition (not all were revised
- Note that the maps don't cover the whole of the state, they are mostly focused towards the coast. Also, there are a few 'holes' (eg Burragorang) where maps towards the coast were not published. This information is based on an index map held in the SLNSW which indicates which maps are in their collection, and it is assumed that they hold all maps which were published.
- 1:31680 (2 inch:mile)
- 1:50000 Army/RASC
- 1st edition (ANG)
- 2nd edition (AGD66/AMG)
- AGD66/AMG - 1st edition & some 2nd edition
- GDA94/MGA - some 2nd edition and 3rd edition (in some cases, 2nd edition is the latest)
- Auto generated paper series (Question - Are these the same as the geopdf's available for purchase?)
- Online vector map (appears to be different, but related to the auto generated series)
- Dunphy map collection
- Large collection (>500) in SLNSW comprised of both published (~25) and unpublished
- In some cases multiple editions of same map, especially those that were published
- Majority of published maps scanned by AA from personal collections, also so unpublished ones
- Other sketch maps
- Various maps published by bushwalkers
- Bushwalking guide book maps
- Most guide books have maps in them, mostly sketch maps by author
- Some are to scale and can be georeferenced, others (eg Jim Smith-How to See the BM) are not but still handy for routes and access
- How to store (object, vector, raster)
- What projection
- Sources of information
- Elevation Data
Well defined and consistant terminology goes a long way to assist in clear and well understood communication.
Refer to the Terminology page for further information.
See http://www.ga.gov.au/scientific-topics/positioning-navigation/geodesy/geodetic-datums for more information on relevant datums for Australia.
What is a Datum?
[Brief explanation of datums. Possibly include a “datum vs projection - what's the difference?” section.]
Reference co-ordinate system used for GPS (Global Positioning System)
WGS84 Bounds: -180.0000, -90.0000, 180.0000, 90.0000
Projected Bounds: -180.0000, -90.0000, 180.0000, 90.0000
Scope: Horizontal component of 3D system. Used by the GPS satellite navigation system and for NATO military geodetic surveying.
GDA94 is the Australian representation of WGS84. There is almost no difference in a 2d sense (Australia has a separate height datum), at least from a bushwalking perspective.
WGS84 Bounds: 108.0000, -45.0000, 155.0000, -10.0000
Scope: Geodetic survey.
Area: Australia - all states
GDA94, ITRF & WGS84 - What’s the difference?
WGS – AGD – GDA: Selecting the correct datum, coordinate system and projection for north Australian applications
The datum used on topographic maps before GDA94. 1st and 2nd Edition topographic maps use the AMG66 projection which is derived from AGD66.
Australian National Grid (ANG)
Prior to 1966 the ANG was used, which covers both the 1:63360 and 1:31680 maps topographic maps.
The ANG makes use of the Clarke 1858 spheroid, where the parameters are expressed in British feet for mainland Australia (and Clarkes feet for Tasmania).
Conversion tool by Anthony Dunk - http://www.binaryearth.net/AusDatumTool/index.php
See http://spatialservices.finance.nsw.gov.au/surveying/geodesy/projections for more information on relevant map projections within NSW.
GDA94 / UTM (EPSG:see below)
There are three UTM projections of GDA94 relevant to NSW.
- EPSG:28354: GDA94 / MGA zone 54 - UTM projection of GDA94 for zone 54
- EPSG:28355: GDA94 / MGA zone 55 - UTM projection of GDA94 for zone 55
- EPSG:28356: GDA94 / MGA zone 56 - UTM projection of GDA94 for zone 56
The Map Grid of Australia 1994: A Simplified Computational Manual
GDA94 / NSW Lambert (EPSG:3308)
Used by NSW GIS systems for whole of state projections.
WGS84 Bounds: 141.0000, -37.5000, 153.6200, -28.1500
Projected Bounds: 8709235.6860, 4009911.3943, 9951732.0554, 5048642.3129
Scope: Natural Resources mapping of whole State.
Area: Australia - New South Wales (NSW)
Web Mercator (EPSG:3857/EPSG:900913)
Used in many popular web mapping applications (Google/Bing/OpenStreetMap). Uses spherical development of ellipsoidal coordinates. Relative to an ellipsoidal development errors of up to 40 km may arise. It is not a recognized geodetic system: see WGS 84 / World Mercator (CRS code 3395).
For details on the issues using Web Mercator for geospatial applications, see the report from the US NGA (National Geospatial-Intelligence Agency) on Implementation Practice Web Mercator Map Projection
Universal Transverse Mecator (UTM)
The international standard projection coordinate system. The parameters of MGA are identical to that of UTM, except that they differ in spheroid (GRS80 vs WGS84)
An ellipsoid (sometimes referred to as a spheroid) is a simplified mathematic representation of the Earths shape. A spheroid can be defined by two parameters, typically: the semi-major axis (alpha) and the inverse flattening (1/f)
The below table summarises relevant values for common spheroids.
|Major Semi Axis (m)||6378293.645||6378160||6378137||6378137|
|Used in||ANG||AGD, AMG||GDA, MGA||GPS|
Further information on geodesy can be found here - myGeodesy
What is it?
In the geographical context, the prominence of a mountain is the elevation differential between the mountain’s summit elevation and its highest pass/saddle connecting it to its parent.
It is of use to bushwalkers as it provides an indication of relative difficulty in the effort required to reach a peak. By applying among other things a prominence criteria, a list of peaks that meet that criteria can be complied. An example is The Abels of Tasmania, where only peaks over 1100m altitude but with a prominence greater than 150m are included.
The prominence criteria is important as it removes high peaks that are near to each other in altitude and would require little elevation gain to travel between them.