Multi-Temporal Image Co-Registration Of Uav Blocks: A Comparison Of Different Approaches

Traditionally, data co-registration of survey epochs in photogrammetry relied on Ground Control Points (GCP) to keep the reference system unchanged. In the last years, Unmanned Aerial Systems (UAV) are increasingly used in photogrammetric environmental monitoring. The diffusion of affordable UAV platforms equipped with GNSS (Global Navigation Satellite System) centimetre-grade receivers might reduce, but not eliminate, the need for GCP. Conversely, if GNSS-assisted orientation cannot be used or if additional ground control and reliability checks are required, alternatives to repeated GCP survey have been proposed, taking advantage of Structure from Motion (SfM) photogrammetry. In particular, co-registering different epochs image blocks together, identifying corresponding features, has been demonstrated as a viable and efficient approach. In this paper four different strategies easily implementable in a generic commercial photogrammetric software are presented and compared considering three different test sites in Italy subject to different amounts of environmental changes. The influence of the amount and distribution of inter-epoch corresponding points on the accuracy of the reconstruction is investigated. The results show that some of the tested strategies obtains very good results and can be used (although not needed) also in RTK centimetre-grade UAV surveys, leveraging the additional information coming from previous epochs survey to actually increase the survey accuracy and reliability

Landslide monitoring by fixed-base terrestrial stereo-photogrammetry

Photogrammetry has been used since long to periodically control the evolution of landslides; however, true monitoring is reserved to robotic total stations and ground based InSAR systems, capable of high frequency, high accurate 24h/day response. This paper presents the first results of a fixed terrestrial stereo photogrammetric system developed to monitor shape changes of the scene. The system is made of two reflex cameras, each contained in a sealed box with a control computer that periodically acquires an image and send it to a host computer; once an image pair is received from the two cameras, the DSM of the scene is generated by image correlation and made available for archiving or analysis. The system has been installed and is being tested on the Mont de la Saxe landslide, where several monitoring system are active. Some instability of the camera attitude has been noticed and is corrected with an automated procedure. First comparisons with InSAR data show a good agreement

MULTI-TEMPORAL IMAGE CO-REGISTRATION OF UAV BLOCKS: A COMPARISON OF DIFFERENT APPROACHES

Abstract. Traditionally, data co-registration of survey epochs in photogrammetry relied on Ground Control Points (GCP) to keep the reference system unchanged. In the last years, Unmanned Aerial Systems (UAV) are increasingly used in photogrammetric environmental monitoring. The diffusion of affordable UAV platforms equipped with GNSS (Global Navigation Satellite System) centimetre-grade receivers might reduce, but not eliminate, the need for GCP. Conversely, if GNSS-assisted orientation cannot be used or if additional ground control and reliability checks are required, alternatives to repeated GCP survey have been proposed, taking advantage of Structure from Motion (SfM) photogrammetry. In particular, co-registering different epochs image blocks together, identifying corresponding features, has been demonstrated as a viable and efficient approach. In this paper four different strategies easily implementable in a generic commercial photogrammetric software are presented and compared considering three different test sites in Italy subject to different amounts of environmental changes. The influence of the amount and distribution of inter-epoch corresponding points on the accuracy of the reconstruction is investigated. The results show that some of the tested strategies obtains very good results and can be used (although not needed) also in RTK centimetre-grade UAV surveys, leveraging the additional information coming from previous epochs survey to actually increase the survey accuracy and reliability

Environment and development in Reconstruction Plans in L'Aquila territory

The operational engagement on the Plans for Reconstruction (earthquake 2009) could allow to propose territorial development in terms of sustainability, informed by energy considerations and the opportunity to establish new activities, related to local economies, based on the search for possible sources of renewable energy and virtuous use of water and waste cycle. In particular, the reclassification of settlements could predispose transition elements, oriented to new concepts of living, which prelude to the definition of a sustainable "city"; we specifically refer to the possibility of developing a "smart" service network and regulating the housing dimension. It lacked, so far, the involvement of the "regional policy" for the guidance and support for the configuration of administrative and financial situations, suitable for a wide participation in fund raising, beyond the mere physical reconstruction

Evaluation of cytological diagnostic accuracy for canine splenic neoplasms : an investigation in 78 cases using STARD guidelines

Cytology represents a useful diagnostic tool in the preliminary clinical approach to canine splenic lesions, and may prevent unnecessary splenectomy. However, few studies have evaluated diagnostic accuracy of cytology in the diagnosis of canine splenic neoplasms. The aim of this study was to determine overall accuracy, sensitivity, specificity, positive and negative predictive values (i.e. diagnostic accuracy indexes) of cytology for canine splenic neoplasms following Standards for the Reporting of Diagnostic Accuracy Studies (STARD) guidelines. A consecutive series of canine splenic cytological samples was retrospectively retrieved from the database of the Diagnostic Pathology Service of the Department of Veterinary Medicine (DIMEVET\u2014University of Milan). Histopathology was set as the diagnostic reference standard. Cytological cases were enrolled when slides were available for review and when the same lesion was submitted for histopathology. Seventy-eight (78) lesions were included in the study. By histopathology, 56 were neoplastic and 22 were non-neoplastic. Cytology had an overall accuracy of 73.08% (95% C.I. 61.84%-82.50%), sensitivity of 64.29% (95% C.I. 50.36%-76.64%), specificity of 95.45% (95% C.I. 77.16%-99.88%), and positive and negative predictive values of 97.3% (95% C.I. 84.01%-99.60%) and 51.22% (95% C.I. 42.21%-60.15%), respectively. Low sensitivity and negative predictive value were balanced by very high specificity and positive predictive value. When positive for neoplasia, cytology represents a useful diagnostic tool to rule in splenic neoplasia, prompting surgery independently from other diagnostic tests. Conversely, a negative cytological result requires additional investigations to confirm the dog to be disease free

Amino acid content and nectar choice by forager honeybees (Apis mellifera L.)

Dual choice feeding tests were performed to determine a preference of forager honeybees for specific amino acids. Artificial nectar containing proline was preferred over those containing only sugars. Nectar containing alanine was preferred on the first day, but preference was no longer significant thereafter. On the contrary, a negative response was found for serine. When the bees were given the choice between two nectars enriched with different compounds, proline was preferred above both alanine and serine, and alanine above serine

Genetic relationships among local Vitis vinifera cultivars from Campania (Italy)

A total of 114 accessions putatively corresponding to 69 local grape cultivars from Campania (Southern Italy) were analysed with 8 microsatellite markers (VVS2, VVMD5, VVMD7, VVMD25, VVMD27, VVMD31, VrZAG62 and VrZAG79) in order to evaluate their genetic diversity and relationships. According to their unique genotype at SSR loci finally 56 varieties were found. Interesting cases of synonymy, i.e. Greco di Tufo and Asprinio, Palummina and Piedirosso, and homonymy were disclosed. Pairwise genetic distances were calculated between all cultivars. Clustering of cultivars did not reflect their current distribution and this suggests that grape cultivars of Campania might have been introduced from various and distinct geographic areas