Can we estimate the distance of animals from the deployed camera trap and their (animal) height from the camera trap images? I do not have reference pictures with measuring scale (Markers) while setting up the camera traps, nor the distance of forest trail/road is documented. Suggestions over image software programs or/and literature that has incorporated methods overcoming these issues are welcome.
Yes, there are ways to estimate the distance of animals from camera trap images. One method is to establish markers at known distances along the midline of the field of view (FOV) and record the frequency of animal detections at each marker. This can be used to estimate the effective detection distance (EDD) of the camera trap. Article A simple method for estimating the effective detection dista...
Ramón De Jesús López Suárez Thank you for the suggestion. The problem with the existing data is I did not set up markers while setting up the camera traps, thus looking for a way to counter it.
Update - The closest solution to my query is in the following publication -
https://www.sciencedirect.com/science/article/abs/pii/S1574954122001844
Thank you for your contribution. I appreciate it. Cheers!!
Yes, few commonly used methods:
1. Known Object Size: If there is a known object of a fixed size in the camera trap image, such as a ruler or a reference object, you can use its size as a reference to estimate the distance of the animal. By comparing the known size of the object with its size in the image, you can calculate the animal's distance using principles of perspective and geometry.
2. Stereo Vision: Stereo vision involves using multiple cameras to capture images from slightly different perspectives. By analyzing the disparity between corresponding points in the two images, it is possible to calculate the depth information and estimate the distance of objects in the scene, including animals.
3. Photogrammetry: Photogrammetry is a technique that uses multiple images of the same object taken from different angles to reconstruct its 3D structure. By analyzing the parallax between different views of the animal in the camera trap images, you can obtain depth information and estimate the distance.
4. Machine Learning: With advancements in computer vision and machine learning, it is possible to train models to estimate the distance of animals directly from camera trap images. By training a model on a dataset containing images of animals at known distances, the model can learn to predict the distance based on visual cues in the images, such as size, perspective, and texture.
It's always recommended to combine multiple approaches and validate the results against ground truth data whenever possible.
Good luck
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