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manual:user_guide:tools:altitude [2015/04/02 14:04] – mstupka | manual:user_guide:tools:altitude [2024/02/16 12:11] (current) – mstupka | ||
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- | ====== Altitude Manager ====== | + | {{ : |
---- | ---- | ||
- | ===== About ===== | + | |
- | Altitude | + | Altitude |
- | * **main settings** | + | * **Settings** |
- | * **settings of altitude offset** | + | * **Offset** |
- | * **settings of pressure sensor** | + | * **Pressure** |
===== Settings ===== | ===== Settings ===== | ||
- | + | Contains general | |
- | ==== Altitude offset ==== | + | |
- | + | ||
- | * **Use altitude offset** - switches | + | |
- | ==== Pressure sensor ==== | + | |
- | + | ||
- | * **Use pressure sensor** - switches on measuring precise | + | |
==== Elevation data ==== | ==== Elevation data ==== | ||
- | | + | <wrap info> |
+ | {{ : | ||
+ | * **Don' | ||
+ | * **Optimize GPS values** - uses offline elevation data to optimize GPS altitude values. | ||
+ | * **Replace GPS values** - uses offline elevation data only for displaying elevation and calculating elevation gain and charts | ||
<WRAP round alert > | <WRAP round alert > | ||
- | **Warning for pilots**: | + | **Warning for pilots**: |
</ | </ | ||
- | |||
- | |||
==== Altitude filter ==== | ==== Altitude filter ==== | ||
- | * **Filter** - applies | + | Applies a filter to altitude |
+ | ===== Altitude offset ===== | ||
+ | {{ : | ||
+ | Altitude calculated by internal or external (Bluetooth) GPS unit is related to a different method of referencing the Earth' | ||
- | ===== Offset ===== | + | Locus Map can define this offset by three methods: |
+ | * **Manual correction** - the basic method used when the exact offset value is known | ||
+ | * **Automatic correction** - a method used in most cases - Locus Map can compute the 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> | ||
+ | * **NMEA correction** - mobile device communicates with GPS unit over special messages called NMEA. These messages contain values of Geoid height that Locus Map can read and apply them to correct this offset.< | ||
- | Altitude calculated by internal 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** | + | ===== Pressure sensor ===== |
+ | {{ : | ||
+ | Some devices are equipped with a barometric pressure sensor. Barometric sensors measure atmospheric pressure very precisely | ||
- | Locus Map can define this offset by three methods: | + | The pressure sensor must be calibrated to a known altitude value so that it can be used for real altitude value calculations. |
- | * **Manual correction** - basic method used when the exact offset value is known | + | * **Automatic** - Locus Map uses GPS altitude or elevation files and current barometric pressure as basic values and relates all other measurements to these values. It also checks measured values |
- | * **Automatic | + | * **Pressure** - current pressure value at a particular sea level as the reference can be obtained from the Internet. The resulting altitude calculation is also quite accurate but the base pressure changes in time so it can be a problem. |
- | * **Altitude NMEA correction** - mobile device communicates with GPS unit over a special messages called NMEA. These messages contain values | + | * **Altitude** - uses some other source |
- | ===== Pressure Sensor | + | <WRAP round important>Some devices |
- | Some devices are equipped with barometric pressure sensor. Barometric sensors measure atmospheric pressure very precisely which can be used for calculating relative altitude changes. I.e. if you know certain pressure at certain altitude you can calculate altitude changes between known and current position. | + | </WRAP> |
+ | ===== Altitude measurement workflow | ||
+ | Locus Map applies the above-mentioned computations in the following order: | ||
- | The pressure sensor must be calibrated to a known altitude | + | * received |
- | * **Automatic** - Locus Map uses GPS altitude or SRTM files altitude and current barometric pressure as basic values and relates all other measurements to these values. It also checks measured values in 2 hour intervals and eventually re-calibrates the pressure sensor.< | + | * using elevation data files (if enabled) |
- | * **Pressure at sea level** - current pressure value at a particular sea level as the reference can be obtained from the Internet. The resulting altitude calculation is also quite accurate but the base pressure | + | * using the pressure |
- | * Altitude - uses some other source of ground altitude - external maps, measuring, tourist guide posts, etc. as the reference. Locus Map then calibrates the pressure sensor according to this value. | + | * final filtering |
- | < | + | If step 2 is missing, the pressure sensor |
+ | <WRAP center round tip> | ||
+ | The **recommended setup** is using elevation data (fully replacing GNSS) without a pressure sensor or using the elevation data only to optimize altitude (useful to eliminate unwanted peaks) + pressure sensor if it's available. | ||
</ | </ | ||