Checking for accurate GPS and Land Ownership
When using iNaturalist to document native bee host plants it is important to note the location accurately. If one is collecting, it important that collection at that location is permitted.
GPS
In Module 2.3 of the OSU Master Melittologist Apprentice Program, Andony Melathopoulos, 13 minutes and 26 seconds into the video, mentions using the mobile app GPS Status to improve the geolocation accuracy of one's iNaturalist record.
https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2&hl=en_CA
https://apps.apple.com/us/app/gps-status-toolbox/id1198499960
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A dedicated GPS utility app such as GPS Status can give one control, diagnostics, and reliability which can matter most when one is trying to make sure one is collecting on where a permit/permission is not required such as Crown Land in BC. Navigation of these lands can often require offline coordinates and these lands, because of remoteness, steep terrain, and dense forests can result in patchy to no coverage with slow to no loading both the maps and of the GPS coordinates. The boundaries of the desired properties can be confusing. A GPS utility app can lock your position with no data connection and show the raw coordinates (handy to mark on Sample Jar labels) which one can compare to offline maps or paper maps, confirming one is on Crown Land and not private or reserve land. Signage of such lands can be minimal.
Normally, when not using a GPS utility app, even in high accuracy mode, the phone can constantly shift between three different positioning systems:
- GPS/GNSS satellites, which are most accurate outdoors, but can be slow to lock, lose signals under canopy, and needs calibration;
- Cell Towers can be fast and work indoors, but can be very coarse with an accuracy of 50-500m;
- Wi-Fi positioning can be good in cities but useless in the wilderness.
Your operating system can report inaccurate locations to iNaturalist as the result of stale Assisted GPS (A-GPS) data because the precise information about each satellites exact orbit and clock (Ephemeris Data) which is normally rapidly downloaded over the internet is slowly broadcast from the satellites with a lower accuracy and can expire in a few hours and A-GPS assistance becomes unreliable after a few days. Also in this set of information is Almanac Data which is a rough map of where the satellites should be over weeks. GPS Status can be used to clear stale ephemeris and almanac data.
Drift can also occur because of: weak satellite geometry (poor angles, few satellites); sensor drift (sometimes seen as your position moving on the map even though you are standing still); phone switching to network assisted location, colds start after periods of inactivity (all of the satellite data needs to be rebuilt from scratch making the first location fix slower); multipath reflections can occur in forests or canyon/rocky terrain (I've seen my canoe map itself up a mountain while we were on a lake), this can be because of signal reflections off rock faces, water, buildings, even the ground.
A GPS utility app such as GPS Status will fully "awake" the phones GPS instead of being on standby to save battery - it will actively search for and enumerate satellites. It will give real time signal to noise monitoring to assess signal quality, reliability, and usability for positioning. This results in a fresh location fix instead of a cached one.
Land Boundaries
An app like AllTrails may show where one is on the map - but more accurately if a GPS utility app is used. All Trails maps don't include Crown Land/Private/Reserve/No-Access Boundaries. iHunter can have Crown Land boundaries included for a nominal fee. This is the boundaries/map app that Bonnie Zand uses for BC. https://bc.ihunterapp.com/
A cadastral layer is the official map of property boundaries — the layer that shows private parcels, reserve lands, and everything that isn’t titled (Crown land). BC’s authoritative cadastral system is ParcelMap BC (PMBC), the official, province‑wide parcel fabric that is continuously updated and is used by government, surveyors, and mapping apps including iHunter.
Crown lands are clearly demarcated in the iHunter app. Interesting is the space that surrounds many rural roadways. Personal favourite Crown Land collection spots are those that border on Conservation Reserves or on Provincial Parks. These Roadside Interface Zones can sometimes yield interesting results though sometimes a corridor for introduced or invasive species as well.
- Cache a larger area than you think you need
- GPS works without cell service, but if you move outside your cached tiles, the map will go blank.
- Cache multiple base map types
- Satellite + Topo is the best combo for backcountry navigation.
- Cache at multiple zoom levels
- iHunter stores tiles per zoom level.
- If you only cache at high zoom, the map may look blank when zoomed out.
- Download over Wi‑Fi
- Caching large areas can be several hundred MB.
Suggested practices for using GPS Status with iHunter when doing remote BC Trips
Know your expected cell coverage
Getting your GPS Status ready for offline accuracy
Clearing the A-GPS data can be performed on GPS Status can be undertaken in the following way. On opening the app the following screen will appear:
Tapping on the screen will open an upper bar that will give access to the menu (red arrow):
The revealed menu below has a choice to manage the A-GPS state (red arrow):
Selecting that menu item will open up choices for resetting the A-GPS XTRA Data (red arrows):
Checking you accuracy (error)
Accurate Geolocation for Field Collection
Before leaving data coverage prime the GPS for the entire day
Open GPS Status and check for your accuracy to be <5-8m. Then Refresh your A-GPS data.
Open iHunter and confirm Crown Land boundaries and pan to cache maps offline.
In the Field maintain a stable drift free GPD fix
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