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manual:user_guide:tools:altitude [2015/04/01 16:37]
mstupka
manual:user_guide:tools:altitude [2016/10/21 16:39] (current)
mstupka
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-====== Altitude Manager ======+{{ :​manual:​user_guide:​ic_altitude_manager_alt.png?​nolink|}}====== Altitude Manager ======
  
 ---- ----
-<todo??</todo>+===== About ===== 
 +<wrap box>Menu > Settings > GPS and location > Altitude manager</wrap> 
 + 
 +Altitude manager enables to fine-tune obtaining altitude values from your mobile device. It is divided into three main tabs: 
 +  * **main settings** 
 +  * **settings of altitude offset** 
 +  * **settings of pressure sensor**
 ===== Settings ===== ===== Settings =====
- +Contains general switches of offset and pressure sensor and settings of SRTM data assistance and altitude measurement filter:\\ {{ :​manual:​user_guide:​tools:​altmanager.png }} 
-==== Altitude offset ​==== +====  SRTM data ==== 
- +{{ :​manual:​user_guide:​tools:​altmanager4.png?​nolink |}} 
-  * **Use altitude offset** - defines offset between real and GPS altitude. More in the **Offset tab**. +  * **No usage** - altitude ​values are acquired from GPS only 
-==== Pressure sensor ==== +  * **Optimize GPS altitude** - uses [[http://​en.wikipedia.org/​wiki/​Shuttle_Radar_Topography_Mission|offline elevation data (SRTM)]] to optimize GPS altitude ​valuesComputed altitude has similar accuracy to an average GPS but does not contain serious errors GPS units usually make. SRTM data can be downloaded [[manual:​faq:​how_to_add_map_shading|several ways]]. 
- +  * **Replace ​GPS values** - uses [[http://​en.wikipedia.org/​wiki/​Shuttle_Radar_Topography_Mission|offline elevation data (SRTM)]] only for displaying elevation 
-  * **Use pressure sensor** - measures precise ​altitude ​by the device in-built pressure sensor More in the **Pressure tab**. +<WRAP round alert > 
-====  Elevation ​data ==== +**Warning for pilots**: optimizing or replacing ​GPS altitude by SRTM data is not recommended for activities when you are **not moving on the ground** - displayed ​altitude values ​are influenced by the ground altitude measuring and calculation 
-  * **Optimize ​GPS altitude** - uses offline elevation data to optimize ​GPS altitude values+</​WRAP>​
 ==== Altitude filter ==== ==== Altitude filter ====
  
-  * Filter - applies ​filter to altitude. Heavier filters cause less fuzzy altitude values but slower reaction on altitude changes. Scale from no filtration to an ultra heavy filter.+Applies ​filter to altitude ​measurement to reduce value fuzziness. Heavier filters cause less fuzzy altitude values but slower reaction on altitude changes. Scale ranges ​from no filtration to an ultra heavy filter
 +===== Altitude offset ===== 
 +{{ :​manual:​user_guide:​tools:​altmanager2.png }} 
 +Altitude calculated by internal or external (Bluetooth) GPS unit is related to a different method of referencing the Earth surface than that used in maps. The difference between them is called **Geoid height** which is distance between [[http://​en.wikipedia.org/​wiki/​Geoid|Geoid]] and [[http://​en.wikipedia.org/​wiki/​Reference_ellipsoid|reference elipsoid]].
  
-===== Offset =====+Locus Map can define this offset by three methods: 
 +  * **Manual correction** - basic method used when the exact offset value is known 
 +  * **Automatic correction** - method used in most cases - Locus Map can compute offset of the whole world from a Geoid model. This method is accurate enough for use in mobile phones and sufficiently precise for all locations (the offset slightly varies based on location). <wrap info>​This method is available in Locus Map Pro only</​wrap>​ 
 +  * **Altitude NMEA correction** - mobile device communicates with GPS unit over a special messages called NMEA. These messages contain values of Geoid height that Locus Map can read and apply them to correct this offset.<​wrap alert>​Some devices report incorrect values so this method is unreliable.</​wrap>​ 
 +  * **Enable also for Bluetooth GPS** - check this option if you use external GPS device
  
-........... +===== Pressure sensor ===== 
-Enable Altitude offset in settings tab before setting offset parameters. +{{ :​manual:​user_guide:​tools:​altmanager3.png }} 
-...+Some devices are equipped with barometric pressure sensorBarometric sensors measure atmospheric pressure very precisely which can be used for calculating relative altitude changesI.eif you know certain pressure at certain altitude you can calculate altitude changes between known and current position.
  
-Pressure +The pressure sensor must be calibrated to a known altitude value so that it can be used for real altitude value calculations. Locus Map offers several methods: 
-............. +  * **Automatic** - Locus Map uses GPS altitude or SRTM files altitude and current barometric pressure as basic values and relates all other measurements to these valuesIt also checks measured values in 2 hour intervals and eventually re-calibrates the pressure sensor.<wrap info>​This method is available in Locus Map Pro only.</​wrap>​ 
-Enable Pressure sensor in settings tab before setting ​pressure ​parameters.+  * **Pressure at sea level** - current pressure value at a particular sea level as the reference can be obtained from the InternetThe resulting altitude calculation is also quite accurate but the base pressure changes in time so it can be a problem. 
 +  * **Altitude** - uses some other source of ground altitude - external maps, measuring, tourist guide posts, etcas the referenceLocus Map then calibrates the pressure sensor according to this value. 
 +<​WRAP ​ round important>​Some devices like e.gSamsung Galaxy Note II turn off the pressure sensor in standby modeIf you want to use pressure sensor during e.gtrack recording, make sure your device maintains the pressure ​sensor on also when the screen goes off. 
 +</​WRAP>​
  
-Automatic 
-Automatic calibration according to GPS 
manual/user_guide/tools/altitude.1427899070.txt.gz · Last modified: 2015/04/01 16:37 by mstupka