6.4 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.
6.4.1 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.
6.4.2 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.
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.
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.
6.4.3 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.