Model Scaling in Smartphone GNSS-Aided Photogrammetry for Fragmentation Size Distribution Estimation

Abstract

Fragmentation size distribution estimation is a critical process in mining operations that employ blasting. In this study, we aim to create a low-cost, efficient system for producing a scaled 3D model without the use of ground truth data, such as GCPs (Ground Control Points), for the purpose of improving fragmentation size distribution measurement using GNSS (Global Navigation Satellite System)-aided photogrammetry. However, the inherent error of GNSS data inhibits a straight-forward application in Structure-from-Motion (SfM). To overcome this, the study proposes that, by increasing the number of photos used in the SfM process, the scale error brought about by the GNSS error will proportionally decrease. Experiments indicated that constraining camera positions to locations, relative or otherwise, improved the accuracy of the generated 3D model. In further experiments, the results showed that the scale error decreased when more images from the same dataset were used. The proposed method is practical and easy to transport as it only requires a smartphone and, optionally, a separate camera. In conclusion, with some modifications to the workflow, technique, and equipment, a muckpile can be accurately recreated in scale in the digital world with the use of positional data.

Fragmentation Size Distribution Measurement by GNSS-Aided Photogrammetry at Real Mine Site

“…The study hypothesizes that this is due to the lack of vegetation in the area, which improved the GNSS accuracy. The study achieved 11.7% scaling error at 400 images, which is close to the extrapolated 10% scaling error at 400 images in the previous experiment on monuments [10]. The error is comparable or more accurate than WipFrag [5,6].…”

“…A previous work by authors [10] proposed a method using GNSS (Global Navigation Satellite System, such as GPS) to get absolute (but rough) camera positions for scaling muckpile fragmentation. The authors showed the potential of the fragmentation size distribution estimation method using rocks similar to muckpiles in the previous work, but the verification test with actual muckpiles and fragmentation size distribution estimation remained an issue.…”

A Simple Way to Reduce 3D Model Deformation in Smartphone Photogrammetry

“…In addition to the large thematic groups described above, one can find a number of publications in which 3D models of various objects were made using images taken from a phone [ 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 ]. Smartphones were also used in radioactivity detection [ 94 ] or in forensic science [ 95 , 96 ].…”

Automating building element detection for deconstruction planning and material reuse: A case study

“…Inherent position information can be utilized if the camera includes global navigation satellite system (GNSS) information (such as a smartphone), as is often used at the UAV-topography scale [41]. However, satellite signals are often unavailable in the building interior context and contemporary smartphone GNSS resolution produces scaling errors of 10% at best [42].…”