Manual · Chapter 9
Map, GPS and GPX
ViolaScope can display geographic information for photos that already contain GPS coordinates and can use GPX tracks to determine locations for photos that do not yet have geographic information.
The map view
Map view provides a geographic perspective on the photos in your project.
Photos with available location information can be represented by their geographic positions.
This makes it possible to review not only when a photo was taken, but also where it belongs geographically.
Existing GPS information
Some cameras, smartphones and other capture devices can store GPS coordinates directly with a photo.
When ViolaScope can read existing geographic information, that location can be used directly in the map workflow.
In this case, no GPX assignment is required simply to display the existing position.
Photos without GPS information
Many cameras do not record a geographic position directly in the image file.
ViolaScope can identify photos in the current project that do not yet have usable GPS information.
A GPX track can then be used as an additional source for determining where those photos were taken.
What a GPX track is
A GPX file can contain a sequence of geographic positions recorded over time.
Each useful track point combines a location with a timestamp.
This makes it possible to compare the capture time of a photo with the timeline of the recorded route.
Load a GPX track
Use the GPX function in the map workflow to load a suitable track file.
Once the track has been loaded, ViolaScope can use its timestamps and geographic positions for the location matching process.
The loaded track can also be displayed on the map so that you can visually inspect the recorded route.
Show or hide the track
The GPX track can be shown when you want to inspect the route together with the photo locations.
It can also be hidden when you want a clearer map view without removing the loaded GPX data from the current workflow.
Time is the connection between photo and track
GPX matching is based on time.
ViolaScope compares the capture time of a photo with the timestamps contained in the GPX track.
A matching position can then be derived from the corresponding part of the recorded route.
Why a time offset may be necessary
The clock in the camera and the clock of the device that recorded the GPX track may not have been synchronized exactly.
Even a relatively small difference can shift the calculated location along the track.
Time-zone differences or an incorrectly set camera clock can create an even larger offset.
ViolaScope therefore allows the time relationship to be adjusted before the proposed locations are applied.
Adjust the time offset
Use the time-offset control when the proposed locations do not correspond to the places where the photos were actually taken.
Changing the offset shifts the photo times used for matching against the GPX track.
You can then inspect the resulting positions again before committing them to the project.
Preview before applying
GPX-based locations are not applied immediately while you are adjusting the matching parameters.
ViolaScope first presents the calculated locations as a preview.
This allows you to inspect the proposed positions on the map and correct the time offset if necessary.
The preview step is especially important when the camera clock and GPX recorder were not synchronized.
Apply the proposed locations
Once the preview is correct, use Apply to confirm the proposed positions.
At that point, the accepted geographic information becomes part of the ViolaScope project state for the affected photos.
Until you apply the proposal, the calculated positions remain part of the preview workflow.
Existing GPS and GPX assignment are different
Existing GPS information and GPX-based assignment are two different situations.
A photo that already contains usable geographic information can be positioned without calculating a new location from a GPX track.
GPX matching is primarily useful for photos that do not already have the required location information.
Check the result visually
The map is an important verification tool during GPX matching.
Before applying a larger number of proposed locations, inspect several photos from different parts of the route.
If the positions appear consistently shifted forward or backward along the track, the time offset is a likely cause.
A practical GPX workflow
A typical workflow can look like this:
- Open the map view.
- Check which photos already contain GPS information.
- Load the GPX track recorded during the photo session.
- Display the track and inspect its route.
- Review the proposed locations for photos without GPS data.
- Adjust the time offset if the positions do not match correctly.
- Check the preview again at several points along the route.
- Apply the locations only when the result is correct.
Map viewing does not modify the original photo
Viewing a photo on the map or loading a GPX track does not alter the visual content of the original image.
GPX-based location assignments that you apply are maintained as part of the ViolaScope project workflow.
Export behavior determines how supported geographic information is carried into the exported result.
Location data and export
Geographic information can be relevant when you later export photos and metadata from ViolaScope.
The export workflow includes controls for how ViolaScope-generated XMP information and transfer metadata handle location data.
The Export chapter explains this distinction in more detail, including the important difference between metadata generated by ViolaScope and GPS information that may already be embedded directly in an image file.
Next step
GPS and GPX add geographic context to the photo workflow. The next chapter introduces Vision Culling, which can analyze groups of photos and provide additional review suggestions.