DEVICE-BASED GEOSPATIAL FILTERING FOR BAROMETRIC PRESSURE SENSOR CALIBRATION
A server generates a gridded geospatial filter map that encompasses the location of a mobile device. The gridded geospatial filter map indicates a first region that is not conducive to calibrating a barometric pressure sensor of the mobile device and a second region that is conducive to calibrating the barometric pressure sensor. The first region and the second region include sub-tiles of the gridded geospatial filter map. The mobile device determines whether the location is conducive to calibrating the barometric pressure sensor based on the location being encompassed by one of the sub-tiles. When the sub-tile is in the second region, the mobile device sends to the server calibration data generated by the barometric pressure sensor, and the server calibrates the barometric pressure sensor using the calibration data. When the sub-tile is in the first region, the mobile device causes the calibration data not to be used.
1 . A method comprising:
determining, by a processor of a mobile device, a location of the mobile device;
transmitting the location from the mobile device to a server;
generating, by one or more processors of the server, a gridded geospatial filter map of a geographical area that encompasses the location of the mobile device, wherein the gridded geospatial filter map indicates a first region that is not conducive to calibrating a barometric pressure sensor of the mobile device and a second region that is conducive to calibrating the barometric pressure sensor, the gridded geospatial filter map is a 2D grid tile, and the first region and the second region include sub-tiles of the gridded geospatial filter map;
transmitting the gridded geospatial filter map from the server to the mobile device;
determining, by the processor of the mobile device, whether the location is conducive to calibrating the barometric pressure sensor based on the location being encompassed by one of the sub-tiles of the gridded geospatial filter map;
when the one of the sub-tiles is in the second region, the processor of the mobile device sending to the server calibration data generated by the barometric pressure sensor, and the one or more processors of the server calibrating the barometric pressure sensor using the calibration data; and
when the one of the sub-tiles is in the first region, the processor of the mobile device causing the calibration data not to be used.
2 . The method of claim 1 , wherein:
the gridded geospatial filter map is one of a plurality of gridded geospatial filter maps for the geographical area that encompasses the location of the mobile device; and
each of the plurality of gridded geospatial filter maps corresponds to one of a plurality of possible uncertainty values for the location of the mobile device.
3 . The method of claim 2 , wherein:
each of the plurality of possible uncertainty values is a multiple of an uncertainty interval value.
4 . The method of claim 3 , wherein:
the uncertainty interval value is 25 meters; and
the plurality of possible uncertainty values is between 25 meters and 200 meters inclusive.
5 . The method of claim 3 , wherein:
the uncertainty interval value is 50 meters; and
the plurality of possible uncertainty values is between 50 meters and 200 meters inclusive.
6 . The method of claim 2 , wherein:
each sub-tile of the gridded geospatial filter map has a flatness metric for a terrain within that sub-tile, the flatness metric depending on the uncertainty value that corresponds to the gridded geospatial filter map; and
for each sub-tile, whether that sub-tile is in the first region or the second region depends on the flatness metric for that sub-tile relative to a flatness threshold value.
7 . The method of claim 6 , wherein:
for each sub-tile, the sub-tile is in the first region if the flatness metric for the uncertainty value that corresponds to the gridded geospatial filter map exceeds the flatness threshold value, and the sub-tile is in the second region if the flatness metric for the uncertainty value that corresponds to the gridded geospatial filter map does not exceed the flatness threshold value.
8 . The method of claim 6 , wherein:
for each sub-tile, the sub-tile is in the first region if the flatness metric exceeds the flatness threshold value for any of the plurality of possible uncertainty values, and the sub-tile is in the second region if the flatness metric does not exceed the flatness threshold value for all of the plurality of possible uncertainty values.
9 . The method of claim 1 , wherein:
the gridded geospatial filter map is a single map based on a combination of a building geospatial filter map and a terrain geospatial filter map.
10 . The method of claim 1 , wherein:
the gridded geospatial filter map comprises a gridded building geospatial filter map and a gridded terrain geospatial filter map; and
the gridded building geospatial filter map and the gridded terrain geospatial filter map are used separately to determine whether the location is conducive to calibrating the barometric pressure sensor based on the location being encompassed by one of the sub-tiles of the gridded building geospatial filter map or the gridded terrain geospatial filter map.
11 . A method comprising:
determining, by a processor of a mobile device, a location of the mobile device;
transmitting the location from the mobile device to a server for the server to generate a gridded geospatial filter map of a geographical area that encompasses the location of the mobile device and to transmit the gridded geospatial filter map to the mobile device, wherein the gridded geospatial filter map indicates a first region that is not conducive to calibrating a barometric pressure sensor of the mobile device and a second region that is conducive to calibrating the barometric pressure sensor, the gridded geospatial filter map is a 2D grid tile, and the first region and the second region include sub-tiles of the gridded geospatial filter map;
determining, by the processor of the mobile device, whether the location is conducive to calibrating the barometric pressure sensor based on the location being encompassed by one of the sub-tiles of the gridded geospatial filter map;
when the one of the sub-tiles is in the second region, the processor of the mobile device sending to the server calibration data generated by the barometric pressure sensor for the server to calibrate the barometric pressure sensor using the calibration data; and
when the one of the sub-tiles is in the first region, the processor of the mobile device causing the calibration data not to be used.
12 . The method of claim 11 , wherein:
the gridded geospatial filter map is one of a plurality of gridded geospatial filter maps for the geographical area that encompasses the location of the mobile device; and
each of the plurality of gridded geospatial filter maps corresponds to one of a plurality of possible uncertainty values for the location of the mobile device.
13 . The method of claim 12 , wherein:
each of the plurality of possible uncertainty values is a multiple of an uncertainty interval value.
14 . The method of claim 13 , wherein:
the uncertainty interval value is 25 meters; and
the plurality of possible uncertainty values is between 25 meters and 200 meters inclusive.
15 . The method of claim 13 , wherein:
the uncertainty interval value is 50 meters; and
the plurality of possible uncertainty values is between 50 meters and 200 meters inclusive.
16 . The method of claim 12 , wherein:
each sub-tile of the gridded geospatial filter map has a flatness metric for a terrain within that sub-tile, the flatness metric depending on the uncertainty value that corresponds to the gridded geospatial filter map; and
for each sub-tile, whether that sub-tile is in the first region or the second region depends on the flatness metric for that sub-tile relative to a flatness threshold value.
17 . The method of claim 16 , wherein:
for each sub-tile, the sub-tile is in the first region if the flatness metric for the uncertainty value that corresponds to the gridded geospatial filter map exceeds the flatness threshold value, and the sub-tile is in the second region if the flatness metric for the uncertainty value that corresponds to the gridded geospatial filter map does not exceed the flatness threshold value.
18 . The method of claim 16 , wherein:
for each sub-tile, the sub-tile is in the first region if the flatness metric exceeds the flatness threshold value for any of the plurality of possible uncertainty values, and the sub-tile is in the second region if the flatness metric does not exceed the flatness threshold value for all of the plurality of possible uncertainty values.
19 . The method of claim 11 , wherein:
the gridded geospatial filter map is a single map based on a combination of a building geospatial filter map and a terrain geospatial filter map.
20 . The method of claim 11 , wherein:
the gridded geospatial filter map comprises a gridded building geospatial filter map and a gridded terrain geospatial filter map; and
the gridded building geospatial filter map and the gridded terrain geospatial filter map are used separately to determine whether the location is conducive to calibrating the barometric pressure sensor based on the location being encompassed by one of the sub-tiles of the gridded building geospatial filter map or the gridded terrain geospatial filter map.