geotagging and mapping photos

Open HoudahGeo. If the program is not on your dock, then it will be in the Applications folder.

HoudahGeo links photos and GPS data by matching the time on the photo with the GPS point with the closest timestamp. 

The HoudahGeo window is divided into three sections:

1. Import photos
2. Add geodata
3. Export geocoded images

Import Photos

In the first step, you can pull in photos from iPhoto, Aperture, or Adobe Lightroom by pushing the "Add Image from Library" button (1). You can also browse through your folders by choosing the "Add Images from Files" button (2).

There is a third, faster option: simply select and drag the files directly into the program.

When adding photos, you will be asked what time zone you took the photos in; choose the appropriate time zone.

In the "Clock error" field, write in the precise number of seconds that your camera's clock is out of sync with the GPS device. The best way we've found to figure out the time delay is to compare the time stamp on the first photo you took with the GPS device clock that appears in your first photo, assuming you took a picture of the GPS clock before you started. Enter the positive or negative time change and click OK.

Once you've added your photos, HoudahGeo will automatically send you to the Import Geodata step. At this point, each of the photos is listed in the window in red text. This indicates that the photos have not been geotagged. When successfully tagged, they will appear as black text.

You can save your project (press Command-S) at this, or any, point.

Adding Geodata

There are four buttons in the geodata step.

1. "Load GPS from Device." This is what we will use. When the pop-up window comes up, choose the Garmin, the USB port and click OK. We've outlined what the other buttons do as well, even though you won't need to use them.

2. "Download GPS data from a file." If you're using other GPS devices, you can browse to your log file.

3. "Manual geocode." Manually locate your photo using a map. This can be somewhat time-consuming. We will not need to do this because we have the tracking info.

4. "Geocode selection using Google Earth." Also a cumbersome process. The program will open the Google Earth application (if you have it installed on your computer) and you will have to locate each point manually.

After clicking the first button, choosing your GPS device and clicking OK, HoudahGeo will match the images with the GPS data. This may take a couple of minutes, and a progress bar will be visible as it works. The location data will appear in the window next to each photo.

As you can see, the geodata has been matched to each photo, and every entry is now in black text, not red as it was previously.

If nothing happens and you don't see location data, double-check that you input the correct time zone. This may happen if you did not properly set the time on your camera, or if you traveled to a different time zone and the GPS, for some reason, still recorded in the last time zone you were in. In that case, you would have to match the camera time zone to the previous time zone you were in. You can change the time zone by going to the top menu and choosing Image: Camera Setup...

Since we have this geotagged photo information, we will soon leave HoudahGeo.

Next Steps

Now you have a few options. The most useful one moves beyond HoudahGeo to create a file that can be uploaded to ZeeMaps. To learn more, please skip to the next step of this tutorial, on uploading photos to a web server.

If you want to use HoudahGeo to work with the geotagged data, your options are limited to these three buttons:

1. Writing the geodata back to each photograph's metadata. This may be useful later if you send the photos to someone else or open it in certain programs because the geodata is embedded in the file itself.

2. Creating a Google Earth compatible file. The advantage of this option is that the actual path you followed, as recorded by the GPS device, will be displayed. One disadvantage is that it can only be viewed in Google Earth--you can't embed this in a blog or web page. You can create either a KMZ file, which is self-contained, or a KML file, which must be properly linked to photos on a web server. (Please note the KMZ only displays properly on Google Earth version 4.2. If you are using the newer Google Earth v. 4.3 beta, only one photo will be visible.)

3. Uploading the geocoded files to Flickr. If you use this option, please ensure that your Flickr Privacy Settings are set to import EXIF location data, so the geodata is properly interpreted.