5.3 Image tagging methods

5.3.3 Tagging images

From the tagging screen, select one or more images for tagging. This can be done by:

• Clicking on the image to select it.
• Clicking and dragging your cursor over groups of images (initial click must be on an image).
• Using Shift, you can click on the first image; then, holding Shift, click on the last image to select all images in between.
• Using Ctrl, you can select multiple images that are not in a consecutive order. This includes being able to drag boxes around multiple subsets of images.
• Selecting images in the panel on the left-hand side of the screen. Note: Selected images will be highlighted in teal in the number panel. Press ESC at any time to deselect highlighted images.
• Apply tag(s) to selected image(s) using the tagging window. With image(s) selected, click on “Tag Selected X”, where X represents the number of images you have highlighted for tagging, and fill in applicable information.
• The tagging form is slightly different when tagging a single image compared to a batch image tagging form:

There are 4 key tagging scenarios you may encounter:

• If you select one or more images with a single individual of a species then a single tag is applied. Once the tag fields are completed, click “Save All and Close” to apply the tag.
• If you select a single image that contains > 1 individual of a single species, but age and/or sex differ among these individuals, then multiple tags are applied. Once you have completed the tag fields for the first individual, click to create a new tag for the next individual.
  • Example: An image with a female deer with a fawn, or a male and female deer together. In this case you would create a unique tag for each individual.

• If you select a single image that contains > 1 species then multiple tags are applied. Once you have completed the tag fields for the first species/individual, click to create a new tag for the next species/individual.
  • Example: An image where a deer triggered the camera and a coyote was also captured in the background. In this case, you would create a tag for the deer and then create a tag for the coyote. 
• If you select multiple images that contain > 1 individual of a single species and age and/or sex differ among these individuals then multiple tags are applied. Once you have completed the tag fields for the first individual, click to create a new tag for the next individual.

5.3.6 Applying camera field of view tags

These tags are only used when the camera field of view is changed compared to the set-up view (see Camera range criteria). During tagging, the “Out of Range” tag is applied to the first image where the area of view changes significantly for three or more hours. This image may be a motion or time-lapse image.

Examples of when to apply an out of range tag include:

• The camera was tilted past the acceptable limits (see camera range criteria)
• The lens was more than 50% covered (by snow, vegetation, fallen trees, etc.)

If the camera returns to the original view, a second “Out of Range” tag can be added to the image immediately before the view was fixed. It is not necessary to tag every image as out of range. WildTrax will complete the process automatically during field of view review. The “Field of View” drop-down menu in the tagging form defaults to “Within” as images are assumed to be within range.

5.3.8 Tagging hints

Images with abundant species that will all have the same tag, such as domestic cows, may be left untagged until the end. Once all other images in the image set (including NONE) have been tagged, you can select the button, and enter the Domestic Cow tag in the tagging window. This will tag all remaining untagged images within that image set on all pages as Domestic Cow. Domestic Cow defaults to VNA for Sex and Age Class, and Number of Individuals; thus this tag can be applied to all images regardless of these variables. This is true for all domestic animals. This can also be done if many images have nothing in them and would be tagged as NONE. However, cannot be used for wild species where the age/sex variable, or number of individuals may vary.

5.3.9 Field of view review

A field of view review is completed only if an “Out of Range” tag is applied during the tagging process, and after all images in an image set have been tagged. The goal is to find out exactly when the camera’s view changed during the deployment period using the previously applied “Out of Range” tag(s). In this step, images are displayed in reverse chronological order (i.e., last photo taken to first photo taken), and all images are included (i.e., motion-triggered, time-lapsed, auto-tagged) in order to inspect the field of view. 

5.3.9.1 Key steps

It is easiest to think of the “Out of Range” tags applied during the tagging process  as bookmarks, which are used to find the exact time a camera field of view changed in the Field of View tab.

• Locate the “Out of Range” tag(s) applied during the tagging process Click the three dots between the page numbers to determine which page has a yellow triangle across it.
• Click on the page with the yellow triangle and locate the last image taken in the field of view. The last good image will occur to the right of the image marked “Out of Range” because images are ordered from last to first taken. Select the last good image, open the tagging form, and select the “END - Last good image in FOV” tag from the Field of View drop-down menu. If the last good image has no associated species tag, you will need to create one.

5.3.9.2 When to use END/START tags

The END/START tags define the observation period and sampling effort for a deployment. Knowing when to apply them can be tricky, but following these instructions will help you use them correctly.

• Apply: When the camera is out of range for more than 3 hours in the middle of the season. The END tag should be applied to the last good photo taken before the camera stopped working properly. The START tag can be applied to the first good image if the camera pops back into position by itself (as occasionally happens when cows or bears lean against the camera post or tree). Discretion is used where (e.g.) cattle are leaning on a post and making the camera go in and out of position repeatedly. In such cases, the camera is said to be not working properly the whole time this is happening. Therefore, an END tag should be applied to the last good image before a cow started leaning on the post and a START tag should be applied if the camera pops back into acceptable position after the cow leaves.
• Don't apply: A START tag at the beginning of an image set to indicate that the camera has been successfully set up. If the camera is out of range for less than 3 hours in the middle of the season.

5.3.9.3 Camera range criteria

This section shows the changes needed for a camera’s view to be considered out of range. When this happens, the observation period ends for the camera. It is important to use the range tags correctly. These tags allow for each camera’s sampling effort to be estimated. A camera’s view can go out of range due to major changes in the roll, pitch, and yaw of the camera.

An END tag is used on the last good image before the view changed sufficiently compared to the set-up images. If the camera angle later moves back into range, you can restart the observation period with a START tag. Note that the START and END tags are only used if the view changes compared to the set-up images.

The following are defined limits for changes to the camera’s view after set-up:

• Roll: The observation period will end if the horizon in an image is tilted more than 30 degrees from level. Note: The lines in the image below show the angle to which the horizon would need to rotate to be considered out of range.
• Pitch: The observation period will end if the camera angle is moved upwards or downwards such that the pole (if used) is either out of view beyond the bottom of the image or above the center of the image.
• Yaw: The observation period will end if the bottom of the pole (if used) is out of view beyond the right or left side of the image.