Abstract
Terrestrial time-lapse photogrammetry is a rapidly growing method for deriving measurements from glacial environments because it provides high spatio-temporal resolution records of change. Currently, however, the potential usefulness of time-lapse data is limited by the unavailability of user-friendly photogrammetry toolsets. Without prior knowledge in photogrammetry and computer coding, such data are used primarily to calculate ice flow velocities or to serve as qualitative records. PyTrx (available at https://github.com/PennyHow/PyTrx) is presented here as a Python-alternative toolset to widen the range of monoscopic photogrammetry (i.e. from a single viewpoint) toolsets on offer to the glaciology community. The toolset holds core photogrammetric functions for template generation, feature-tracking, image registration, and georectification (using a planar projective transformation model). In addition, PyTrx facilitates areal and line measurements, which can be detected from imagery using either an automated or manual approach. Examples of PyTrx's applications are demonstrated using time-lapse imagery from Kronebreen and Tunabreen, two tidewater glaciers in Svalbard. Products from these applications include ice flow velocities, surface areas of supraglacial lakes and meltwater plumes, and glacier terminus profiles.
Highlights
Other than for glacier surface velocity measurements, monoscopic time-lapse photogrammetry remains an under-used technique in glaciology
The majority of monoscopic photogrammetry toolsets are either distributed as programming scripts or with graphical user interfaces, and for those without prior knowledge in photogrammetry and computer coding, their applications are largely limited to calculating glacier surface velocities (e.g., Kääb and Vollmer, 2000; Messerli and Grinsted, 2015; James et al, 2016; Schwalbe and Maas, 2017)
Ten class objects perform the core photogrammetry processes that were outlined in the previous section: ground control points (GCPs), Digital Elevation Model (DEM), CamCalib, CamImage, ImageSequence, Homography, Velocity, Area, Length, and CamEnv
Summary
Terrestrial photogrammetry is a rapidly growing technique in glaciology as a result of its expanding capabilities in the digital computing era, with applications in monitoring change in glacier terminus position (e.g., Kick, 1966), glacier surface conditions (e.g., Parajka et al, 2012; Huss et al, 2013), supraglacial lakes (e.g., Danielson and Sharp, 2013), meltwater plume activity (e.g., Schild et al, 2016; How et al, 2017; Slater et al, 2017), and calving dynamics (e.g., Kaufmann and Ladstädter, 2008; Ahn and Box, 2010; James et al, 2014; Whitehead et al, 2014; Petlicki et al, 2015; Medrzycka et al, 2016; Mallalieu et al, 2017; How et al, 2019) It provides adequate spatial resolution and a temporal resolution that can surpass airborne and satellite-derived measurements, with flexible data-capture that is relatively easy to control. PyTrx’s capabilities will be demonstrated and evaluated using time-lapse imagery from Kronebreen and Tunabreen, two tidewater glaciers in Svalbard
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
