Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
en:help:1.4:geolocation [2014/11/05 19:21]
alpinequest
en:help:1.4:geolocation [2017/09/12 11:21] (current)
Line 4: Line 4:
 The GPS position allows you to display your real location on the map. The GPS position allows you to display your real location on the map.
  
-Most devices now have a GPS chip which is used to compute this location. GPS provides a precise location while not using any cellular network. However, it must have a clear access to the sky, meaning that it cannot be using indoor.+Most devices now have a GPS chip which is used to compute this location. GPS provides a precise location while not using any cellular network. However, it must have a clear access to the sky, meaning that it cannot be used indoor.
  
 {{ :​en:​help:​1.4:​geolocation:​submenu.jpg?​nolink}} ​ {{ :​en:​help:​1.4:​geolocation:​submenu.jpg?​nolink}} ​
  
-{{:​icon_help.png?​nolink}} If your device doesn'​t have the GPS chip, or this one is turned off in the Android settings, the network location (much less precise) may be used.+{{:​icon_help.png?​nolink}} If your device doesn'​t have GPS chip, or if this one is turned off in the Android settings, the network location (much less precise) may be used.
  
 To turn on the GPS positioning and display your real location on the map, you can either: To turn on the GPS positioning and display your real location on the map, you can either:
-  * Long-press the "''​**GPS ​Position**''"​ menu button {{:​icon_01.png?​nolink}};​ +  * Long-press the "''​**GPS ​position**''"​ menu button {{:​icon_01.png?​nolink}};​ 
-  * Open the GPS position ​sub-menuand click on the "''​**Activate**''"​ toggle button {{:​icon_03.png?​nolink}}.+  * Open the sub-menu and click on the "''​**Positioning details**''"​ toggle button {{:​icon_03.png?​nolink}}.
  
 {{:​icon_help.png?​nolink}} The GPS may require up to few minutes to retrieve your precise location after being turned on. {{:​icon_help.png?​nolink}} The GPS may require up to few minutes to retrieve your precise location after being turned on.
Line 19: Line 19:
 ===== The sub-menu ===== ===== The sub-menu =====
  
-Click on the "''​**GPS ​Position**''"​ menu button {{:​icon_01.png?​nolink}} to display the sub-menu, containing the following items:+Click on the "''​**GPS ​position**''"​ menu button {{:​icon_01.png?​nolink}} to display the sub-menu, containing the following items:
   * The "''​**Positioning details**''"​ button {{:​icon_02.png?​nolink}} opens the positioning details panel;   * The "''​**Positioning details**''"​ button {{:​icon_02.png?​nolink}} opens the positioning details panel;
   * The "''​**Positioning details**''"​ toggle {{:​icon_03.png?​nolink}} activates or deactivates the positioning;​   * The "''​**Positioning details**''"​ toggle {{:​icon_03.png?​nolink}} activates or deactivates the positioning;​
   * The "''​**Rotate the map (using GPS)**''"​ check-box {{:​icon_04.png?​nolink}} activates or deactivates the map rotation to make it match your current GPS orientation (you must be moving);   * The "''​**Rotate the map (using GPS)**''"​ check-box {{:​icon_04.png?​nolink}} activates or deactivates the map rotation to make it match your current GPS orientation (you must be moving);
-  * The "''​**Display distance line**''"​ check-box {{:​icon_05.png?​nolink}} activates or deactivates the drawing of a line from the map center to your current location including its distance; +  * The "''​**Display distance line**''"​ check-box {{:​icon_05.png?​nolink}} activates or deactivates the drawing of a line from the map center to your current location including its distance ​(see {{:​icon_07.png?​nolink}} below)
-  * The "''​**Positioning status**''"​ check-box {{:​icon_06.png?​nolink}} activates or deactivates the display of a box on the map giving the most important positioning information.+  * The "''​**Positioning status**''"​ check-box {{:​icon_06.png?​nolink}} activates or deactivates the display of a box on the map giving the most important positioning information ​(see {{:​icon_08.png?​nolink}} below).
  
  
 ===== The menu icon ===== ===== The menu icon =====
  
-The "''​**GPS ​Position**''"​ menu button {{:​icon_01.png?​nolink}} icon and color lets you know the current state:+The "''​**GPS ​position**''"​ menu button {{:​icon_01.png?​nolink}} icon and color let you know the current state:
  
-{{:​en:​help:​1.4:​geolocation:​menu-off.jpg?​nolink}} When the icon is white, the "''​**GPS Position**''" ​is turned off. Long-press the button to turn it on.+{{:​en:​help:​1.4:​geolocation:​menu-off.jpg?​nolink}} ​ When the icon is white, the GPS positioning ​is turned off. Long-press the button to turn it on.
  
-{{:​en:​help:​1.4:​geolocation:​menu-on-locked.jpg?​nolink}} When the icon is green, the "''​**GPS Position**''" ​is turned on and the current location is displayed at the map center (or being searched). Long-press the button to turn it off.+{{:​en:​help:​1.4:​geolocation:​menu-on-locked.jpg?​nolink}} ​ When the icon is green, the GPS positioning ​is turned on and the current location is displayed at the map center (or being retrieved). Long-press the button to turn it off.
  
-{{:​en:​help:​1.4:​geolocation:​menu-on-unlocked.jpg?​nolink}} When the icon is green with a lock key, the "''​**GPS Position**''" ​is turned on and the current location is currently not displayed at the map center (you'​re looking somewhere else on the map). Click on the button to center the map on the current location. +{{:​en:​help:​1.4:​geolocation:​menu-on-unlocked.jpg?​nolink}} ​ When the icon is green with a lock key, the GPS positioning ​is turned on and the current location is currently not displayed at the map center (you'​re looking somewhere else on the map). Click on the button to center the map on the current location.
- +
-{{:​en:​help:​1.4:​geolocation:​on-map-positioning.jpg?​nolink }}+
  
  
 ===== The on-map positioning ===== ===== The on-map positioning =====
 +
 +{{ :​en:​help:​1.4:​geolocation:​on-map-positioning.jpg?​nolink}}
  
 When turned on, the GPS will try to compute your location based on the information retrieved from GPS satellites. When turned on, the GPS will try to compute your location based on the information retrieved from GPS satellites.
  
-The localisation ​information box let you know how much satellites have been found yet. In this case, ''​**0/5sats**''​ means that ''​**5**''​ satellites have been found in the sky, but ''​**0**''​ are being currently ​used. It means that the current location ​haven'been computed ​yet.+If the "''​**Positioning status**''"​ option is checked, an information box {{:​icon_08.png?​nolink}} lets you know how much satellites have been found yet. In this case, ''​**4/8sats**''​ means that ''​**8**''​ satellites have been found in the sky, and ''​**4**''​ are being used to compute ​the current location. If ''​**0**''​ satellites are being used, then the current location has not been found yet.
  
-In some cases, the application can reuse a previously computed location while the new one is being computedIn this case, the old location ​is displayed in red like in the previous screen-shot.+If your current location has been foundthis one is displayed in blue on the map {{:​icon_09.png?​nolink}}. A circle indicates ​the area of precision (your real location ​is somewhere inside the circle, usually but not necessarily at the center)An arrow indicate your direction (while moving)and the information box {{:​icon_08.png?​nolink}} gives you the following information:​ 
 +  * The current ​location ​accuracy, its elevation, speed, and fix number; 
 +  * The distance and bearing to the map center (if different).
  
-When the application ​is sent in the background (like when another ​one is started)the localisation ​is temporarily deactivated to save battery.+{{:​icon_help.png?​nolink}} In some cases, while retrieving the current location, ​the application ​can display an older one. In this casethis old location ​is displayed in red.
  
-In addition to your location, the Localisation provides useful information such as your current altitude and speed.+{{:​icon_help.png?​nolink}} When the application is sent in the background (or when another one is started over), the positioning is temporarily deactivated to save the battery. This default behavior can be deactivated in the application settings.
  
  
 ===== Elevations management ===== ===== Elevations management =====
  
-The elevation of a point is the difference between the altitude of this point and a reference surface of altitude 0 (also called "sea level").+The elevation of a point is the difference between the altitude of this point and a reference surface of altitude 0 (usually the sea level).
  
 However, depending on what is considered to be the surface of reference, elevations can be quite different. This surface depends on the representation of the Earth, which has been shaped in many ways over the last centuries. However, depending on what is considered to be the surface of reference, elevations can be quite different. This surface depends on the representation of the Earth, which has been shaped in many ways over the last centuries.
Line 63: Line 65:
 The GPS, working worldwide, had to choose a system defining a shape that match the entire Earth. A particular oblate spheroid, called [[http://​en.wikipedia.org/​wiki/​World_Geodetic_System|WGS84]] has been chosen as shape, because it provides a good overall approximation while remaining simple. The GPS, working worldwide, had to choose a system defining a shape that match the entire Earth. A particular oblate spheroid, called [[http://​en.wikipedia.org/​wiki/​World_Geodetic_System|WGS84]] has been chosen as shape, because it provides a good overall approximation while remaining simple.
  
-Based on this choice, GPS's "​WGS84"​ elevations are a good approximation at the Earth scale, but compared to per-country systems elevations, we can have discrepancies up to 50m.+Based on this choice, GPS's "​WGS84"​ elevations are a good approximation at the Earth scale, but compared to per-country systems elevations, we can have discrepancies up to 100m. 
 + 
 +**To reduce these discrepancies and provide more precise elevations, the application convert all GPS elevations towards another system using a more precise shape of the Earth, the [[http://​en.wikipedia.org/​wiki/​Geoid|Geoid]],​ which is called EGM96. However, some slight discrepancies can still be found.**
  
-**To reduce these discrepancies and provide more precise elevations, the application convert all GPS elevations towards another system using a more precise shape of the Earth, called ​[[http://​en.wikipedia.org/​wiki/​Geoid|Geoid]]. ​However, some slight discrepancies can still be found.**+{{:​icon_help.png?​nolink}} You can find detailed articles on [[http://​en.wikipedia.org/​wiki/​Geoid|the Geoid]] ​and on [[http://en.wikipedia.org/​wiki/​Figure_of_the_Earth|the shape of the Earth]] on Wikipedia.
  
-{{:icon_help.png?​nolink}} ​You can find a detailed article of the shape of the Earth on [[http://​en.wikipedia.org/​wiki/​Figure_of_the_Earth|Wikipedia]].+Here is the difference between GPS and Geoid altitudes all around the world (from Wikipedia):​ 
 +{{ :en:help:1.4:​geolocation:​elevations-management.jpg?nolink }}

Choose language:

Online help