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Documentation/Wiki/Field_Collection_Data_Practices.md

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+# Field Collection of Plus Code Locations
+[<img src="https://play.google.com/intl/en_us/badges/images/generic/en_badge_web_generic.png" width="200">](https://play.google.com/store/apps/details?id=org.odk.collect.android)
+
+## Summary
+
+Collecting locations of equipment, buildings, homes etc from the field, and obtaining the plus codes, is a common problem.
+
+[Open Data Kit](https://opendatakit.org) is a suite of free and open source software to support collecting, managing and using data. [Open Data Kit Collect](https://play.google.com/store/apps/details?id=org.odk.collect.android) (ODK Collect) is a free, open source app available in the Google Play Store for customizable data collection in an offline environment.
+
+This document explains how to get started with ODK to collect location data and convert it to plus codes.
+
+**Note:** This process will collect latitude and longitude and convert them to global plus codes, e.g. 8FVC9G8F+6W.
+Converting these to plus code addresses (9G8F+6W Zurich, Switzerland) is out of scope of this data collection. (One way it could be done is using the [Google Maps Geocoding API](https://developers.google.com/maps/documentation/geocoding/intro).)
+
+## Overview
+
+First we will define a [form](https://docs.opendatakit.org/form-design-intro/) that specifies what data we want, and then use [ODK Collect](https://docs.opendatakit.org/collect-intro/), an Android app, to collect filled in forms.
+
+ODK Collect saves location information as latitude and longitude, so the final step will be to convert those to plus codes using the [plus code add-on for Google Sheets](https://gsuite.google.com/marketplace).
+
+## Requirements
+
+* ODK Collect runs on Android devices
+* The field workers will need Google accounts (we're going to use Google Drive and Sheets).
+
+## Alternatives
+
+Other options for collecting this data might be to use Google Maps - manually long pressing on the map displays an address card, and expanding that shows the plus code.
+
+Alternatively, you could write an HTML5 web app or develop another mobile app.
+These could do the conversion from GPS coordinates to plus codes directly.
+However, we think that using Open Data Kit provides the fastest route to general functionality.
+
+## Using Open Data Kit
+
+Here is a [description of using ODK with Google Drive and Sheets](https://www.google.com/earth/outreach/learn/odk-collect-and-google-drive-integration-to-store-and-manage-your-data).
+
+This procedure can be followed exactly, or a slightly easier method to define the form is described below.
+
+## Online Form Editor
+
+That document uses a Google Sheet to define the form.
+This can be complicated to test and debug.
+A simpler way is to use the [online form editor](https://build.opendatakit.org/).
+
+This provides a drag and drop method to sequence the form questions and set the field names, list of options etc.
+
+You can build a basic flow with location collection, and include additional metadata such as the time of collection, the phone number etc.
+
+You will need to create a blank Google Sheet.
+Name one of the tabs "Form Submissions" or similar, copy the URL of that tab and set it as the `submission URL` in the form (using Edit -> Form Properties).
+
+The, save the form and export it (with File -> Export to XML), and then transfer that XML file to your Google Drive account. (Putting it in a folder together with the spreadsheet will make sharing those files to your field workers easy.)
+
+### Location Notes
+
+You can select whether to use Google Maps or OpenStreetMap in the general settings.
+You can also select whether to display the street map, or aerial imagery.
+
+ODK Collect will only use GPS locations when it can see a minimum number of satellites.
+If your field workers will be using it indoors, then the GPS location may not be available.
+Instead, you can set the field to not use GPS but allow a [user entered location](https://docs.opendatakit.org/form-question-types/#geopoint-with-user-selected-location) - but that will not collect accuracy or altitude, and may also be inaccurate.
+
+A better solution is to use the manual location as a fallback to GPS.
+You can have one question that uses the GPS location (with or without a map), and a second question that gets the location manually, and only show that question if the GPS is not available, or the location accuracy was poor.
+
+If using the online editor, enter the following in the **Relevance** field for the manual location field:
+```
+not(boolean(/data/gps_location)) or number(/data/gps_location)>15
+```
+
+(This assumes the data name of the GPS location field is `gps_location`.)
+
+If building your form in a spreadsheet, put the following in the **survey** tab:
+
+| type | name | label | relevant | appearance |
+|------|------|-------|----------|------------|
+| geopoint | gps_location | GPS location |  | maps
+| geopoint | manual_location | Manual location | `not(boolean(${gps_location})) or number(${gps_location})>15` | placement-map
+
+# Configuring ODK Collect
+
+Install and configure ODK Collect as described in the [document](https://www.google.com/earth/outreach/learn/odk-collect-and-google-drive-integration-to-store-and-manage-your-data).
+
+The document also describes how to use it and upload completed forms to the Google Sheet.
+
+# Converting Locations To Plus Codes
+
+ODK uploads locations to the sheet using three fields:
+* location (decimal degrees)
+* altitude (set to zero for manual locations)
+* accuracy (set to zero for manual locations)
+
+To convert these to plus codes, install the Google Sheets plus code add-on from the [G Suite Marketplace](https://gsuite.google.com/marketplace).
+You can convert a column of locations into their corresponding plus codes using the formula:
+```
+=PLUSCODE(B:B)
+```
+This will use the default precision code length, 10 digits.
+If you need a different precision, specify the code length in the formula:
+```
+=PLUSCODE(B:B, 11)
+```
+Installing and using the Google Sheets Plus Codes add-on is covered in a series of videos:
+
+[![Google Sheets Plus Codes add-on video playlist](https://i.ytimg.com/vi/min-u1w4SOQ/hqdefault.jpg)](https://www.youtube.com/watch?v=n9kJC5qVeS0&list=PLaBfOq9xgeeBgOLyKnw8kvpFpZ_9v_sHa)