manual:user_guide:tools:altitude
Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revision | |||
| manual:user_guide:tools:altitude [2016/10/21 16:39] – mstupka | manual:user_guide:tools:altitude [2022/04/08 11:54] (current) – mstupka | ||
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| Locus Map can define this offset by three methods: | Locus Map can define this offset by three methods: | ||
| * **Manual correction** - basic method used when the exact offset value is known | * **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). | + | * **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). |
| * **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.< | * **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.< | ||
| * **Enable also for Bluetooth GPS** - check this option if you use external GPS device | * **Enable also for Bluetooth GPS** - check this option if you use external GPS device | ||
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| 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: | 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 values. It also checks measured values in 2 hour intervals and eventually re-calibrates the pressure sensor.<wrap info> | + | * **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. |
| * **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 changes in time so it can be a problem. | * **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 changes in time so it can be a problem. | ||
| * **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. | * **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. | ||
manual/user_guide/tools/altitude.txt · Last modified: 2022/04/08 11:54 by mstupka
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