braindump
Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
braindump [2016/08/21 14:57] – [Spheroids] allchin09 | braindump [2018/10/08 23:26] – [Web Mercator (EPSG:3857/EPSG:900913)] allchin09 | ||
---|---|---|---|
Line 29: | Line 29: | ||
===== Geographic Names Board ===== | ===== Geographic Names Board ===== | ||
- | * why are co-ordinates | + | * why are coordinates |
- | * Spoke with GNB Secretariat (Susan Fietz - susan.fietz@lpi.nsw.gov.au) on the matter (27 April 2016): | + | * AA spoke with GNB Secretariat (Susan Fietz - susan.fietz@lpi.nsw.gov.au) on the matter (27 April 2016): |
* What is on the GNB website is the official name places list | * What is on the GNB website is the official name places list | ||
* Updating of the list planned to start within the next few years | * Updating of the list planned to start within the next few years | ||
* Any corrections are welcome | * 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 " | ||
+ | * 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 | ||
====== Licensing ====== | ====== Licensing ====== | ||
Line 119: | Line 128: | ||
==== 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. |
==== Australian National Grid (ANG) ==== | ==== Australian National Grid (ANG) ==== | ||
Line 157: | Line 166: | ||
===== Web Mercator (EPSG: | ===== Web Mercator (EPSG: | ||
- | Used in many popular web mapping applications (Google/ | + | Used in many popular web mapping applications (Google/ |
+ | |||
+ | For details on the issues using Web Mercator for geospatial applications, | ||
+ | Web Mercator Map Projection]] | ||
===== Universal Transverse Mecator (UTM) ===== | ===== Universal Transverse Mecator (UTM) ===== | ||
Line 167: | Line 179: | ||
====== Ellipsoids ====== | ====== Ellipsoids ====== | ||
- | An ellipsoid (sometimes referred to as a spheroid) is a simplified mathematic representation of the earths | + | An ellipsoid (sometimes referred to as a spheroid) is a simplified mathematic representation of the Earths |
The below table summarises relevant values for common spheroids. | The below table summarises relevant values for common spheroids. | ||
Line 173: | Line 185: | ||
[[http:// | [[http:// | ||
+ | ^Parameter | ||
+ | ^Major Semi Axis (m) | 6378293.645 | ||
+ | ^Inverse Flattening | ||
+ | ^Used in | ANG | AGD, AMG | GDA, MGA | GPS | | ||
+ | |||
+ | Further information on geodesy can be found here - [[https:// | ||
+ | |||
+ | ====== Prominence ====== | ||
+ | |||
+ | ===== 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.// | ||
+ | |||
+ | [[http:// | ||
+ | |||
+ | 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. | ||
+ | |||
+ | ===== How is it calculated? ===== | ||
+ | |||
+ | [[https:// | ||
+ | |||
+ | [[https:// | ||
braindump.txt · Last modified: 2021/03/07 22:06 by allchin09