Automatic geocoding in HoudahGeo matches photos to a GPS track log. A track log is a record of where you have been. A GPS app or track logger records your current position and the current time. It does so every few seconds and thus creates a breadcrumb trail of your travels.
HoudahGeo figures out where you took a photo by matching the timestamp on the photo with the times in the GPS track log. While the GPS device gets accurate time information from satellites, your camera clock is probably not accurate. Most cameras also do not record time zone information: the photo coming out of the camera may say it was taken at 12 PM, but there is no telling if that is to be understood as 12 PM east coast or west coast – a 3-hour difference.
Timestamps in HoudahGeo
HoudahGeo needs to know the exact time a photo was taken. That is why HoudahGeo asks about camera clock settings when you import images.
There are 4 ways you can tell HoudahGeo about your camera clock settings. The first 3 are found in the Load > Camera Setup… panel. This panel pops up automatically when you import photos that lack time zone information.
You can skip Camera Setup… – accept the current settings – and proceed to import more images and GPS track logs. We will correct the camera clock settings later by matching a key photo to a spot on the track log.
Match to a GPS track
A GPS track log tells HoudahGeo where you have been and when. HoudahGeo can figure out camera clock settings if you show it where one of your photos was taken.
In Process mode, select a photo of which you know exactly where you took it. This could be a street corner, an outlook, or any other location you are able to pick out on a map.
Zoom the map to that location. Be sure to have Map > Show Tracks enabled. Click the track at the exact location where you took the photo. HoudahGeo will show the location coordinates as well as the date and time at that location.
Click the camera icon next to this information. The Camera Setup panel will open with the Photo Time settings to match the selected photo to the time on the track log. Confirm the settings and click OK.
With the updated camera clock settings, HoudahGeo will proceed to geocode all images in your project. You can also trigger geocoding and adjust settings from Process > Geocode using GPS Data….