QGIS plugin or web app? Lessons learned in the development of a 3D georeferencer

Abstract

Collections of historical images are currently being scanned to stop their degradation and to enable a numeric exploitation. These collections have a high cultural, artistic and scientific value. However, they are not fully exploited because the photographs do not have a georeference (geographic information cannot be extracted from the picture) and are poorly labeled (makes searching in a database inefficient). During the last years, we developed a QGIS plugin and a web app dedicated to the georeferencing of photographs and the linking of images with spatial data. In this paper, we discuss the technologies involved and compare both implementations. The results suggest that both approaches are valuable but provide different advantages in term of target users and development effort.

The 2004–2005 Mt. Etna Compound Lava Flow Field: A Retrospective Analysis by Combining Remote and Field Methods

“…It was used to calculate, by comparison with 2004 LiDAR DEM, the volume of the earlier flows. TINITALY DEM is a 10‐m resolution DEM derived from the 1:10,000 scale numeric 1998 topographic map of the Provincia Regionale di Catania (Sicily), published in 1999 Single optical and thermal images collected during the eruption were elaborated following the principles of single‐image photogrammetry using both Pic2Map QGIS plugin (Produit et al., 2016) and an implemented ad‐hoc code to obtain orthorectified images of the lava during its emplacement. Orthorectified images were then analyzed in a GIS environment to map the flows during their advancement LiDAR data acquired soon after the onset of the eruption and after its end (i.e., on September 16, 2004 and September 29, 2005) were used to map and calculate lava volume, area and thickness A set of optical and thermal images collected during the eruption was used to generate a 3D model and DEM of the lava field when it was active using multi‐view photogrammetry methods.…”

“…Single optical and thermal images collected during the eruption were elaborated following the principles of single‐image photogrammetry using both Pic2Map QGIS plugin (Produit et al., 2016) and an implemented ad‐hoc code to obtain orthorectified images of the lava during its emplacement. Orthorectified images were then analyzed in a GIS environment to map the flows during their advancement…”

“…In this work, camera poses of thermal and optical (digital) images were assessed using the single‐image photogrammetry method implemented in the Pic2Map QGIS Python Plugins (https://plugins.qgis.org/plugins/Pic2Map), which uses the 2D‐3D correspondence between an image and the DEM to compute unknown parameters of the camera (Produit et al., 2016). The reference map we used was the 2004 LiDAR‐derived DEM from which we also extracted the elevation data.…”

Interactive Snow Avalanche Segmentation from Webcam Imagery: results, potential and limitations

“…Since most webcams are mounted in a stable position, always capturing the same area, they may be georeferenced for a transfer of the avalanche area identified in the image to a map. There are several monophotogrammetry tools available to georeference single images, initially developed to georeference old photographs (e.g., Bozzini et al, 2012Bozzini et al, , 2013Produit et al, 2016;Golparvar and Wang, 2021). Only with existing georeferencing the detected avalanches can be exactly geolocated, compared by size, aspect or slope angle as well as imported into existing long-term databases.…”

“…ing of the avalanches, achievable with e.g. monophotogrammetry tools likeBozzini et al (2012Bozzini et al ( , 2013;Produit et al (2016)…”