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braindump [2018/10/08 11:42]
allchin09 [Ellipsoids]
braindump [2021/03/07 11:06] (current)
allchin09 [Half of NSW topographic maps no longer printed]
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 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. 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 [[http://spatialservices.finance.nsw.gov.au/__data/assets/pdf_file/0008/219455/SpatialServices_Topoletter.pdf|here]]
 +
 +[[http://maps.ozultimate.com/?id=1534338535930|Interactive map of 'digital only' maps]]
 +
 +{{ ::digitalonlymaps.jpg |}}
 +
 +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 ===== ===== Geographic Names Board =====
  
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 ===== Topographic maps ===== ===== Topographic maps =====
  
-  * 1:63360 (inch:mile)+  * 1:63360 (inch:mile)
     * 1st edition     * 1st edition
     * 2nd edition (not all were revised     * 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.     * 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 (inch:mile)+  * 1:31680 (inch:mile)
   * 1:50000 Army/RASC   * 1:50000 Army/RASC
     * 1st edition (ANG)     * 1st edition (ANG)
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     * Elevation Data     * Elevation Data
       * [[http://www.ga.gov.au/elvis/|ELVIS - Elevation Information System]]       * [[http://www.ga.gov.au/elvis/|ELVIS - Elevation Information System]]
 +
 +====== Terminology ======
 +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.
  
 ====== Datums ====== ====== Datums ======
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 ==== AGD66 ==== ==== AGD66 ====
  
-The datum used on topographic maps before GDA94. 2nd Edition topographic maps use the AMG66 projection which is derived from AGD66.+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) ==== ==== Australian National Grid (ANG) ====
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 [[http://www.binaryearth.net/AusDatumTool/AustralianNationalGrid.html]] [[http://www.binaryearth.net/AusDatumTool/AustralianNationalGrid.html]]
  
-The ANG makes use of the Clarke 1858 spheroid.+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).
 ===== Datum Conversions ===== ===== Datum Conversions =====
  
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 ===== Web Mercator (EPSG:3857/EPSG:900913) ===== ===== 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 800 meters in position and 0.7 percent in scale may arise. It is not a recognized geodetic system: see WGS 84 / World Mercator (CRS code 3395).+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 [[http://earth-info.nga.mil/GandG/wgs84/web_mercator/(U)%20NGA_SIG_0011_1.0.0_WEBMERC.pdf|Implementation Practice 
 +Web Mercator Map Projection]]
  
 ===== Universal Transverse Mecator (UTM) ===== ===== Universal Transverse Mecator (UTM) =====
braindump.1538998924.txt.gz · Last modified: 2018/10/08 11:42 by allchin09