GeoTrace User Manual

Note: the screenshots in this manual were captured with the app in Korean. The app itself switches to English under Settings → Language; each caption explains what the screen shows.

1. Why GeoTrace

The free and open-source mobile GIS and GPS apps available today run into limits during real field survey work.
GeoTrace keeps the philosophy of traditional GIS modules — creating lines, polygons, points and tracks as GIS objects.
It adds what those tools lack: the many kinds of handwritten notes that are awkward to express as GIS objects in the field are returned as GIS objects, ready to use for reference in QGIS.

2. Platform

Android only for now. iOS devices are not yet available for testing; an iPad and iPhone build will be tested and released once hardware can be sourced.
To get the most out of the app on a phone or tablet you need a stylus — a Galaxy S Pen or the stylus supplied with your tablet.
Without a pen you can still sketch and take notes with your finger.

3. Base maps

The developer is Korean, so the default base map is VWorld — the online base map most widely used in Korea. Google satellite imagery is also available for users outside Korea.
Users outside Korea can add the WMS or XYZ tile services used in their own country by writing an XML file and importing it as a base map.

3.1. Adding a base map

Create an .xml file in the format shown below.
Copy the file to your device (for example, the Download folder).
In the app, open the base map menu → Import from XML and pick the file.
Imported maps are saved and stay in the list the next time you launch the app.

XML example

<?xml version="1.0" encoding="UTF-8"?>
<mapSources>
    <source
      name="MAP NAME"
      url="https://example.com/tiles/{z}/{x}/{y}.png"
      minZoom="0"
      maxZoom="19"
      servers="" />
</mapSources>

Attribute	Default	Description
`name`	required	Name shown in the menu
`url`	required	`{z}/{x}/{y}` tile address
`minZoom`/`maxZoom`	0/19	Zoom range at which the map is drawn
`servers`	none	Server list substituted into `{s}` (for example a,b,c)
`type`	xyz	`xyz` or `wms`
`role`	base	`base` (base map) or `overlay` (layer drawn on top)

Extra attributes for WMS — layers (required), version (1.3.0), crs, format (image/png), transparent (true), opacity (0.7), attribution, and authType · key · domain when authentication is required.

A ready-made set of worldwide sources is included in this repository — download it and import it with Import from XML:

Download world map sources (XML)

3.2. Things to watch for

Replace any & in a URL with &.
An entry with an empty name or url is not registered. Give every map a distinct name.
Even if you list several values in servers, only the first one is actually used.
To use a WMS as a base map its CRS must be EPSG:3857. Any other CRS can only be drawn as an overlay.
Check the tile provider's terms of service before you use a source.

4. Main menu

The eight main menu buttons explained — Figure 1. Main menu. Top row: notes and sketch mode, create survey point, GPS on/off, recenter on current location. Bottom row: track recording, base map selection and settings, project settings, app settings. The round handle collapses and expands the menu bar.

5. Sketch mode (handwriting and drawing)

Write and draw directly on the map with a pen paired to your phone or tablet.
Everything you draw is stored as a vector object, ready to use in QGIS.
Sketch objects carry a marker that helps you find them as you zoom in and out. The marker is only a screen aid — it is not written to the exported GPKG.

The drawing toolbar explained — Figure 2. Drawing tools, left to right: pen, highlighter, eraser, finger-drawing mode for devices without a stylus, undo and redo. Below are the colour swatches and the −/+ control for stroke thickness.

Survey areas sketched over satellite imagery — Figure 3. Sketching in practice — highlighted areas, hand-drawn boundaries and species notes over satellite imagery.

6. Adding survey points

With GPS on, drop a point at your current location.
Or tap the map to place a point wherever you choose.
Each point is labelled with its name attribute. Tap a point to view and edit its attributes.

Figure 4. Adding a survey point — choose current location or pick on the map, enter a name and description, and the labelled marker appears. Tapping it opens the attribute view and edit panel.

7. Recording tracks and the GPS panel

Track line colour and thickness are configurable under Settings.
The GPS panel shows signal strength, the coordinates of your current position (latitude and longitude), altitude, direction of travel, and the device heading on a 16-point compass (N, NW, S and so on).
Coordinates can be shown as decimal degrees or DMS. Set this under Settings, or tap the panel to switch format on the spot.
Press and hold the GPS panel to copy the current coordinates to the clipboard.

Figure 5. Track recording and the GPS panel — the route is drawn as you walk, the coordinate format toggles between decimal degrees and DMS, and a long press copies the coordinates.

8. Base map settings and overlay maps

The app is built around Korea, so the VWorld base map is shown by default.
An overlay map draws a vector map on top of imagery. In Korea, for example, you can put VWorld Hybrid over VWorld Satellite to show place names, roads and other vector information on top of the imagery.

Switching the base map and selecting an overlay — Figure 6. Switching base maps and adding an overlay — pick a map from the list, then use *Overlay map settings* to layer a hybrid map over the imagery.

9. Saving maps for offline use

For areas with no mobile data, download the map of the area you plan to survey while you still have a connection, then use it offline.

Downloading an offline map — Figure 7. Offline map download — select an area, set the zoom range, and the app reports the tile count and estimated size before downloading.

Follow each provider's terms of service. Some sources — Google among them — restrict bulk downloading, and compliance is the user's responsibility.

10. Project management

Project management covers importing the GIS data you want to overlay on the map, managing layer symbology, and resetting the current survey.

10.1. Importing GIS files

Import data you prepared beforehand in a desktop GIS.
Supported formats are GPKG, KML and KMZ. GeoTIFF support is planned.
Imported files are drawn with the default symbology shown below.

Figure 8. Importing a GIS file — choose *Import GIS file* from the project menu, pick the file, and the layer is drawn on the map.

10.2. Managing layers

Layer management controls the symbology of the GIS data you imported.
Set fill colour, polygon opacity and labels.

Editing layer symbology — Figure 9. Layer management — fill colour and opacity, outline colour and width, label field and label text size.

10.3. Exporting results as ZIP/GPKG

Export the tracks, points and handwritten notes you recorded in the field as a single ZIP file.
Unzip it and inspect the contents in QGIS or any other GIS.
Inside the ZIP, field_result.gpkg holds all of the data — points, sketches and tracks.

Exporting results as a ZIP file — Figure 10. Exporting results — choose *Save result ZIP/GPKG* from the project menu and give the file a name.

Result layers opened in QGIS — Figure 11. The result in QGIS — survey_point, sketch_stroke and route_line load as vector layers, aligned to the imagery.

11. Settings

Settings are grouped into three sections: General, Display and Track.
General holds the language setting and the GPS recording interval — how often a position is recorded while a track is being saved (1, 5 or 10 seconds).
The compass setting corrects the GPS panel's bearing when the device sensor is off.
Display covers the saved track, point labels and colours.
Track adjusts how routes are drawn — the colour of the track being recorded and the colour of imported tracks.

The settings screens — Figure 12. Settings — General (language, GPS recording interval, compass), Display (colour, size, labels) and Track (route being recorded, saved routes).

12. Other features

12.1. Hiding the menu and landscape mode

The main menu at the top of the screen can be collapsed with the hide button. In landscape mode the menu moves to the right-hand side of the display, where it can also be collapsed.

Hiding the menu, in portrait and landscape — Figure 13. Hiding the menu — the bar sits at the top in portrait and on the right in landscape, and the round handle collapses it either way.

12.2. Coordinate and address lookup

Press and hold anywhere on the map to show the latitude and longitude of that point, along with its street address (Korean users only).
Address lookup requires a VWorld API key, which you enter once on first use.

To obtain a VWorld API key:

Go to VWorld Digital Twin Korea → Open API → Issue authentication key.
Fill in the service name, service type and service URL, tick Geocoder API under the APIs to use, and submit the request.
Open the key management page, copy the issued key, and enter it in the app.

VWorld Open API reference page — Figure 15. VWorld Open API — the *Issue authentication key* menu.

VWorld key request form — Figure 16. Requesting a key — select *Geocoder API* in the list of APIs to use.

VWorld key management page — Figure 17. Key management — copy the issued key and enter it in the app.

12.3. Editing GPKG symbology and using Package Layers

Style the GIS data you use in the field in QGIS, then combine two or more layers into a single GPKG with the Package Layers tool and import that into the app.
The polygon colours and labels you set in QGIS are carried through and drawn the same way in the app.

Editing forest-type map symbology in QGIS — Figure 18. Styling in QGIS — set polygon colours and labels before packaging.

The QGIS Package Layers dialog — Figure 19. Package Layers — bundles several layers into one GeoPackage. Keep *Save layer styles into GeoPackage* ticked so the styling travels with the data.

The packaged data displayed in the app — Figure 20. The same data in the app — colours and labels from QGIS are preserved, and tapping a polygon shows its attributes.