Virtual plaster cast: digital 3D modelling of lion paws and tracks using close‐range photogrammetry

Abstract

The ecological monitoring of threatened species is vital for their survival as it provides the baselines for conservation, research and management strategies. Wildlife studies using tracks are controversial mainly due to unreliable recording techniques limited to two-dimensions (2D). We assess close-range photogrammetry as a low-cost, rapid, practical and reliable field technique for the digital threedimensional (3D) modelling of lion (Panthera leo) paws and tracks. Firstly, we tested three reconstruction parameters affecting the 3D model quality. We then compared direct measurements on the paws and tracks versus the same measurements on their digital 3D models. Finally, we assessed the minimum number of photographs required for the 3D reconstruction. Masking, auto-calibration and optimisation provided higher reconstruction quality. Paws masked semi-automatically and tracks Based on the predicted error, the minimum number of photographs required for an accurate reconstruction is seven (paws) or eight (tracks) photographs. This field technique, using only a digital camera and a ruler, takes less than one minute to sample a paw or track. The introduction of the 3D facet provides more realistic replications of paws and tracks that will enable a better understanding of their intrinsic properties and variation due to external factors. This advanced recording technique will permit a refinement of the current methods aiming at identifying species, age, sex and individual from tracks.

Estimation of body weight in captive Amur tigers (Panthera tigris altaica)

“…This also probably contributed to prediction error. So, further studies may find it necessary to develop software technology to automatically extract the body measurements of Amur tigers, or to develop new methodology to eliminate parallax error, such as 3D geometric morphometrics (Marchal et al 2016(Marchal et al , 2017.…”

A Fluid Dynamics Approach for Assessing the Intelligent Geomorphic Design of the Japanese Pufferfish Nest

“…Digital photogrammetry techniques such as "Structure from Motion", able to calculate the relative three-dimensional positions of points on an object by monitoring their motion across a number of overlapping images from a single moving camera [14], are increasingly used within academia to process survey images into three-dimensional spatial data such as textured polygonal models. Numerous studies have shown its effectiveness in the reconstruction of topology [15][16][17][18][19], archaeological sites [20], animal morphology and tracks for ecological monitoring [21]. The procedure follows three main steps: (1) matching feature points are mapped across multiple overlapping images to form tie points.…”

Interpol review of shoe and tool marks 2016-2019

“…Photogrammetry was employed by Faulkner [ 58 ], who studied the usability of applying the commercially available software package PhotoScan [ 59 ] to reconstruct 3D shoe impressions. Photogrammetry is used to construct a 3D model based on typically two or more 2D images, taken from different angles (typically the more images are used, the better the resulting 3D model is [ 60 ]). To this end, 3D data was reconstructed from impressions in sand from a used running shoe.…”