Demystifying the Differences between Structure-from-MotionSoftware Packages for Pre-Processing Drone Data

Abstract

With the increased availability of low-cost, off-the-shelf drone platforms, drone data become easy to capture and are now a key component of environmental assessments and monitoring. Once the data are collected, there are many structure-from-motion (SfM) photogrammetry software options available to pre-process the data into digital elevation models (DEMs) and orthomosaics for further environmental analysis. However, not all software packages are created equal, nor are their outputs. Here, we evaluated the workflows and output products of four desktop SfM packages (AgiSoft Metashape, Correlator3D, Pix4Dmapper, WebODM), across five input datasets representing various ecosystems. We considered the processing times, output file characteristics, colour representation of orthomosaics, geographic shift, visual artefacts, and digital surface model (DSM) elevation values. No single software package was determined the “winner” across all metrics, but we hope our results help others demystify the differences between the options, allowing users to make an informed decision about which software and parameters to select for their specific application. Our comparisons highlight some of the challenges that may arise when comparing datasets that have been processed using different parameters and different software packages, thus demonstrating a need to provide metadata associated with processing workflows.

Optimising UAV Data Acquisition and Processing for Photogrammetry: A Review

“…Four different pieces of photogrammetric software (Agisoft Metashape, SimActive Correlator 3D, Pix4D Mapper, Web Open Drone Map) were compared in the study [110]. Processing time and output photogrammetric products were analysed.…”

The unique value proposition for using drones to map coastal ecosystems

“…The number of research papers referenced in this review alone attests to the many diverse challenges in translating drone data to knowledge and actionable insights. From the variety of software packages and number of parameters to consider even in the pre-processing stages of photogrammetry (Pell et al, 2022), deriving analysis-ready data such as orthomosaics and digital elevation models is not always a simple process. After conducting the initial processing, users need to develop skills in manipulating large volumes of data, building reliable and reproducible workflows, and translating downstream products to communicate their meaning.…”

Human-Induced Hydrological Connectivity: Impacts of Footpaths on Beach Wrack Transport in a Frequently Visited Baltic Coastal Wetland

“…WebODM uses multiple techniques and software libraries to process aerial image data. Orthophotos are generated by stitching individual, overlapping orthorectified aerial images producing a single file, that is then georeferenced and converted to a GeoTIFF (Vacca, 2020;Pell et al, 2022). A first step in this process is the generation of a textured 3D point cloud that represents the landscape which was captured by the UAV in several single images.…”

“…WebODM extracts a surface model by using an inverse distance weighting interpolation method and the model is then smoothed using a media filter to remove noise (Vacca, 2020). Pell et al (2022) Weather data for the monitoring period was provided by the German Weather Service (DWD) and water level at the nearest station (Kiel lighthouse) was recorded by the Federal Waterways and Shipping Administration (WSV) and provided by the Federal Institute for Hydrology (BfG). Major events were storm Arwen (known as Hannelore in Germany), storm Malik (known as Nadia in Germany), and storm Eunice (known as Zeynep in Germany, see Figure 3).…”