Today we are featuring a guest post from Michele Mattix of Geomattix, LLC.
While there are many ways to add digital photos to your GIS, I find that using GPS is the easiest – provided you have a useful workflow. Finding that workflow, however, can be extremely frustrating due to the myriad of GPS and camera hardware and software options. In this multiple-part blog, I will attempt to shed light on this topic so you can find the equipment and workflow that’s right for you. The information for these articles is taken from my Adding Digital Photos to Your GIS e-course.
Georeferenced Photos as Layers
You’ve decided that you want to add digital photos to your GIS. Great! Now you need to determine how you’d like the photos to behave. Basically, you have two options. One is to have a georeferenced photo that is added as its own layer in ArcMap. Because it is georeferenced, the photo is mapped in projected coordinate space so you can see it on your map in its proper location. This method is useful for showing landscape features, perhaps to show how features and terrain change over time. It is also a good way to create a geoscrapbook to document a journey as I’ve done for one of my Sedona hikes, below.
There are a number of ways to use GPS to georeference digital photos. The workflow you use depends on the hardware and software you want to use. The goal of each is the same – assign geographic coordinates to the EXIF header of your photos – a process called geotagging. Equipment options include the following:
- A GPS unit with an integrated camera
- A GPS unit with a connected camera
- A GPS unit with a stand-alone camera and office software for photo-linking
Digital Photos as GIS Attributes
The second way to store digital photos in your GIS is to include them as attributes of your GIS features. Here, the photo itself is not georeferenced but is instead tied to a GIS point, line, or polygon. For example, I maintain a GIS point dataset for Sedona hiking trails called ‘Trailheads’. I store a photo of each trailhead as an attribute of the feature in a field named ‘Photo’, see below. Though the photo will not appear as its own layer in ArcMap, I can use the Identify and Hyperlink tools to open the photo when clicking on the feature.
For this type of GIS photo storage, you will need to create a text field in your GIS attribute table to store the path and name of the photo. You can add your photo paths and names manually in an edit session – just type the pathname in the appropriate attribute table cell. Depending on where you store the photos relative to where you store the ArcMap MXD, you can omit the full path name as I did in the example above. If you only have a few photos, then manually entering the text is acceptable. If you have a lot of photos, however, this method is inefficient.
This is where GPS can help. GPS can automate the photo-linking so that digital photos taken in the field are automatically linked to the appropriate GIS feature. Again, there are a number of workflows you can employ to accomplish this task – each based on your GPS and camera hardware and software tools. These include the following:
- GPS unit with an integrated digital camera and appropriate field software
- GPS unit with a connected digital camera and photo-linking field software
- GPS unit with a stand-alone digital camera and photo-linking software for use in the office
Once you’ve decided whether you want your GIS photos to be georeferenced layers or stored as attributes of other features, you can begin to identify the appropriate GPS, camera, and software tools you will need. In the next article, I will go into more detail about using GPS to geotag your photos.
Michele Mattix is an ESRI authorized ArcGIS trainer and certifed Trimble GPS instructor.
