Estimate distance from camera trap to animal — ct_camtrap_animal

Calculates the radial distance between a camera trap and an animal detected in an image using geometric principles and reference markers.

Usage

ct_camtrap_animal_distance(fov, forward_distance, ref_halfwidth, animal_offset)

fov: Numeric. The camera's horizontal field of view in degrees. Common values range from 30° to 60° depending on camera model.
forward_distance: Numeric. The forward distance (in meters) from the camera to the animal along the central axis, estimated using reference markers visible in the image.
ref_halfwidth: Numeric. The measured half-width of the camera's field of view in the image at distance forward_distance, in any unit (e.g., cm, pixels). This is typically measured with a ruler on the photo or using image analysis software.
animal_offset: Numeric. The measured horizontal offset of the animal from the central vertical line in the image, in the same units as ref_halfwidth.

Numeric. The estimated radial distance (in meters) from the camera to the animal.

distance <- ct_camtrap_animal_distance(
  fov = 35,
  forward_distance = 7.5,
  ref_halfwidth = 12,
  animal_offset = 3
)