133 research outputs found
Towards Semantic Photogrammetry: Generating Semantically Rich Point Clouds from Architectural Close-Range Photogrammetry
No full textDevelopments in the field of artificial intelligence have made great strides in the field of automatic semantic segmentation, both in the 2D (image) and 3D spaces. Within the context of 3D recording technology it has also seen application in several areas, most notably in creating semantically rich point clouds which is usually performed manually. In this paper, we propose the introduction of deep learning-based semantic image segmentation into the photogrammetric 3D reconstruction and classification workflow. The main objective is to be able to introduce semantic classification at the beginning of the classical photogrammetric workflow in order to automatically create classified dense point clouds by the end of the said workflow. In this regard, automatic image masking depending on pre-determined classes were performed using a previously trained neural network. The image masks were then employed during dense image matching in order to constraint the process into the respective classes, thus automatically creating semantically classified point clouds as the final output. Results show that the developed method is promising, with automation of the whole process feasible from input (images) to output (labelled point clouds). Quantitative assessment gave good results for specific classes e.g., building facades and windows, with IoU scores of 0.79 and 0.77 respectively
Metallographical investigations of lead, lead-tin, lead-silver, and lead-antimony alloys
No full textLead and lead alloys were metallographically investigated. These materials are used for shaped charge liners. The material data, i.e., hardness, strength, breaking elongation and grain size, and the measurement techniques are presented. The influence of the composition of alloys on the material data is described
Influence of cold forming and recrystallization on pure copper
No full textA fine grain texture and low strength of copper is achieved by a high cold working rate and a following recrystallization procedure. For OFHC copper of 99.9 percent the data are presented and the measuring techniques are described
Testing of different pure iron qualities
No full textIn diesem Bericht wird beschrieben, welche Unterschiede in den Materialeigenschaften von Reineisen bestehen und wie diese durch Wärmebehandlungen beeinflußt werden. Die Probenpräparation für metallographische Untersuchungen wird geschildert und Gefügeaufnahmen erläutert. Die Ergebnisse sollen dazu dienen, den Einfluß des Materialzustandes auf die Hochgeschwindigkeitsumformung in Sprengversuchen abschätzen zu können. Differences in the material properties of pure iron caused by heat treatments are described. The sample preparation for the metallographic investigations is presented and the texture is explained. The results can be used to estimate the influence of the material properties on the high-dynamic forming in explosive tests
WHY IT MAKES SENSE TO USE HIGH COST SENSORS TO DO LOW COST SENSOR RESEARCH
No full textThe question is highly topical in the world that is aiming to acclaim more efficiency through an omnipresence of sensors. The implication of the omnipresence of sensors clearly is that most of these sensors will be of the low-cost type. Hence, there is a call for research utilizing low-cost sensors. However, paradoxically, it often makes sense to use high-cost sensors to do this research. Here, we open up this apparent paradox and argue why high-cost sensors are not only greatly useful but also critically required in low-cost sensor research. We offer different examples that support this argument but discuss also limitations and cases where the argument does not hold
Impact of freezing/thawing procedures on the post-thaw viability of cryopreserved human saphenous vein conduits
No full textBACKGROUND: Cryopreserved human blood vessels are important tools in reconstructive surgery. However, patency of frozen/thawed conduits depends largely on the freezing/thawing procedures employed. METHODS: Changes in tone were recorded on rings from human saphenous vein (SV) and used to quantify the degree of cryoinjury after different periods of exposure at room temperature to the cryomedium (Krebs-Henseleit solution containing 1.8M dimethyl sulfoxide and 0.1M sucrose) and after different cooling speeds and thawing rates following storage at -196 degrees C. RESULTS: Without freezing, exposure of SV to the cryomedium for up to 240 min did not modify contractile responses to noradrenaline (NA). Pre-freezing exposure to the cryomedium for 10-120 min attenuated significantly post-thaw maximal contractile responses to NA, endothelin-1 (ET-1) and potassium chloride (KCl) by 30-44%. Exposure for 240 min attenuated post-thaw contractile responses to all tested agents markedly by 62-67%. Optimal post-thaw contractile activity was obtained with SV frozen at about -1.2 degrees C/min and thawed slowly at about 15 degrees C/min. In these SV maximal contractile responses to NA, ET-1 and KCl amounted to 66%, 70% and 60% of that produced by unfrozen controls. Following cryostorage of veins for up to 10 years the responsiveness of vascular smooth muscle to NA was well maintained. CONCLUSION: Cryopreservation allows long-term banking of viable human SV with only minor loss in contractility
Cultural heritage documentation and integrated geomatics techniques in an educational context: case Bois-du-Luc (Belgium)
No full textThe Walloon Region in Belgium played a leading role in the world economy and in the industrial sciences and engineering since the 19th century. Several relicts, such as important industrial buildings or sites, are spread over a large area and are still dominating the current landscape. Some of these remnants are preserved as monuments, representing the industrial, cultural and ecological transition of the region during the last two centuries. Since 2012, UNESCO recognized the importance of four of the best preserved 19th and 20th century coal mining sites and classified them as World Heritage ("Major Mining Sites of Wallonia", Le Grand-Hornu, Bois-du-Luc, Le Bois du Cazier and Blegny Mine). The four recognised mining sites together form a strip of about 170 km long, containing important examples of the so-called 'neo classical architecture' from the early periods of the industrial era in continental Europe. Motivated by this recognition and by the huge touristic and educational potential of the sites, a partnership between the Walloon government and Ghent University was organized. In this first stage, the collaboration focuses on the site of Bois-du-Luc in the municipality of La Louviere, containing a large series of dwellings, several equipments built between 1853 and 1923 by the Societe des Charbonnages du Bois-du-Luc, workshops and heaps. Consisting of numerous buildings dating back to the period between 1838 and 1923, this site is one of Europe's oldest collieries.
The collaboration between the Walloon government and Ghent University - Department of Geography fits in the hands-on training which students in land surveying and geomatics receive during their Bachelor studies. For the students it is very interesting that their practical exercises are not limited to the university campus, but that they are involved in a real measurement campaign. The project consists of a series of intensive land surveying campaigns, resulting in highly detailed and accurate maps of the site, including the inside domain of the buildings. Already available aerial photographs are processed to obtain a 3D model of the site and the wider region. In March 2013, the first campaign took place. During this first campaign, a topographical network was set out and a series of detail points were measured for the detailed topographic mapping. The topographical network was well-planned and covers almost the whole site, forming a set of permanently materialized reference points for later measurements. Besides, a large number of ground control points (GCPs) were taken for the 3D reconstruction of the area, based on high resolution airborne imagery. This enables the students to familiarize themselves with photogrammetric principles in a practical exercise. Both the topographic maps and the 3D model fit within the large scale geographic reference map of the Walloon Region.
In this contribution, the results of this intensive trans-regional collaboration on the preservation of the sites are presented. This paper will discuss the first deliverables from the project and the advantages for the responsible government, the cultural heritage organisations (Ecomusee du Bois-du-Luc) and the students. The main focus here is on the educational context of the project. Furthermore, future projects on the same site will be discussed
Current Approaches in Complexity Management – Practical and Theoretical Implications for Distribution Networks
No full textIn the up to date competition, the optimal degree of complexity severely influences the success of distribution networks and therefore the success of the entire company. Nevertheless, it seems that up to now, limited research has been done on distribution network complexity. Therefore, this paper deals with current theoretical and practical approaches of complexity management in distribution networks. Methodologically, first an in-depth literature review is conducted, highlighting the existing complexity handling tools in different areas. Since this analysis shows that no approach specifically copes with the requirements of distribution networks, exploratory expert interviews are carried out. Comparing the findings shows that neither literature, nor industrial practice investigate or institutionalize complexity management in distribution networks. Thus, this paper provides opportunities to close this gap. On the one hand, a framework which can be used to elaborate suitable complexity management strategies for distribution networks is presented. On the other hand, the relevant areas of distribution networks are narrowed down in order to create a basis for developing a comprehensive method for complexity management in distribution systems
CLOSE RANGE UAV ACCURATE RECORDING AND MODELING OF ST-PIERRE-LE-JEUNE NEO-ROMANESQUE CHURCH IN STRASBOURG (FRANCE)
No full textClose-range photogrammetry is an image-based technique which has often been used for the 3D documentation of heritage objects.
Recently, advances in the field of image processing and UAVs (Unmanned Aerial Vehicles) have resulted in a renewed interest in
this technique. However, commercially ready-to-use UAVs are often equipped with smaller sensors in order to minimize payload and
the quality of the documentation is still an issue. In this research, two commercial UAVs (the Sensefly Albris and DJI Phantom 3
Professional) were setup to record the 19th century St-Pierre-le-Jeune church in Strasbourg, France. Several software solutions
(commercial and open source) were used to compare both UAVs’ images in terms of calibration, accuracy of external orientation, as
well as dense matching. Results show some instability in regards to the calibration of Phantom 3, while the Albris had issues
regarding its aerotriangulation results. Despite these shortcomings, both UAVs succeeded in producing dense point clouds of up to a
few centimeters in accuracy, which is largely sufficient for the purposes of a city 3D GIS (Geographical Information System). The
acquisition of close range images using UAVs also provides greater LoD flexibility in processing. These advantages over other
methods such as the TLS (Terrestrial Laser Scanning) or terrestrial close range photogrammetry can be exploited in order for these
techniques to complement each other
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