NUMERICAL SIMULATION OF ECCENTRICITY CREATION IN THE PRODUCTION OF HOT ROLLED TUBES

The paper deals with the issue of eccentricity in the technological node of the piercing press, under selected conditions, which result from the possibilities of production in the conditions of ŽP a.s. These conditions were verified and adapted to the rolling process. This process consisting of individual technological nodes on the rolling mill, in which eccentricity is created on the piercing press and the following steps eliminate it in other technological nodes. For quality analysis of manufacturing tubes using numerical simulation, it is necessary to know the actual state of eccentricity creation on the rolling mill. A numerical simulation of piercing under different input conditions was used (software DEFORM-3D) and was performed for several different charge states before entering onto the piercing press. The eccentricity itself has a significant effect on the resulting geometric quality of the tubes.

A Technical Review of Planet Smallsat Data: Practical Considerations for Processing and Using PlanetScope Imagery

With the ability to capture daily imagery of Earth at very high spatial resolutions, commercial smallsats are emerging as a key resource for the remote sensing community. Planet (Planet Labs, Inc., San Francisco, CA, USA) operates the largest constellation of Earth imaging smallsats, which have been capturing multispectral imagery for consumer use since 2016. Use of these images is growing in the remote sensing community, but the variation in radiometric and geometric quality compared to traditional platforms (i.e., Landsat, MODIS, etc.) means the images are not always ‘analysis ready’ upon download. Neglecting these variations can impact derived products and analyses. Users also must contend with constantly evolving technology, which improves products but can create discrepancies across sensor generations. This communication provides a technical review of Planet’s PlanetScope smallsat data streams and extant literature to provide practical considerations to the remote sensing community for utilizing these images in remote sensing research. Radiometric and geometric issues for researchers to consider are highlighted alongside a review of processing completed by Planet and innovations being developed by the user community to foster the adoption and use of these images for scientific applications.

EXPERIMENTS USING SMARTPHONE-BASED VIDEOGRAMMETRY FOR LOW-COST CULTURAL HERITAGE DOCUMENTATION

The rapid development of 3D scanning technology is a welcome progress in the field of tangible cultural heritage documentation. While active sensors such as handheld Time-of-Flight (ToF) cameras and lidar have recently generated much hype, developments in low-cost imaging sensors have also seen long strides in recent decades. This paper aims to see the potential of videogrammetry for the purposes of heritage documentation. This technique has existed for decades, but we argue that when combined with modern smartphone sensors and proper photogrammetric processing workflow it may present an interesting low-cost solution for 3D scanning. Furthermore, the paper wishes to address the requirement for a certain geometric quality in heritage documentation and how the proposed method may fulfil them. For this reason, comparisons between the videogrammetric result and traditional DSLR close range photogrammetry will be described to determine its suitability for heritage documentation. Results show that using modern low-cost smartphone imaging sensors, a good compromise between geometric quality and overall cost in the context of cultural heritage recording is possible to achieve.

FIRST ASSESSMENTS INTO THE USE OF COMMERCIAL-GRADE SOLID STATE LIDAR FOR LOW COST HERITAGE DOCUMENTATION

Heritage documentation has benefitted greatly from significant developments in sensor technology during the past two decades. Miniaturisation of sensors is also an important aspect in the development of low cost sensors, always interesting in heritage projects where budgetary constraints are often present. Among these sensors, the solid-state lidar has begun to attract attention, partly due to its integration in Apple Inc.’s latest version of the iPhone and iPad series. We hypothesise that this type of sensor will see a lot of use in the near future; however, the question remains whether they are sufficient for heritage documentation purposes. In this paper, results from the 2020 iPad Pro SSL point cloud will be assessed and compared to more traditional techniques for 3D scanning (photogrammetry and terrestrial laser scanning). While understandably the geometric quality of benchmark-level techniques such as these remain undeniably better, at least for the moment, the paper concludes that SSL sensors may nevertheless be sufficient for some lower-precision applications.

ACCURACY INVESTIGATION ON IMAGE-BASED CHANGE DETECTION FOR BIM COMPLIANT INDOOR MODELS

Construction progress documentation is currently of great interest for the AEC (Architecture, Engineering and Construction) branch and BIM (Building Information Modeling). Subject of this work is the geometric accuracy assessment of image-based change detection in indoor environments based on a BIM. Line features usually serve well as geodetic references in indoor scenes in order to solve for camera orientation. However, building edges are never perfectly built as planned and often geometrically generalized for BIM compliant representation. As a result, in this approach, line correspondences for image-to-model co-registration are considered as statistically uncertain entities as this is essential for dealing with metric confidences in the field of civil engineering and BIM. We present an estimation model for camera pose refinement which is based on the incidence condition between model edges and corresponding image lines. Geometric accuracies are assigned to the model edges according to the Level of Accuracy (LOA) specification for BIM. The approach is demonstrated in a series of tests using a synthetic image of an indoor BIM. The effects of varying edge detection accuracies on the estimation are investigated as well as the effects of using model edges with different geometric quality by adding Gaussian noise to the synthetic observations, each within 100 simulation runs. The results show that the camera orientation can be improved with the presented estimation model as long as the BIM compliant references meet the conditions of LOA 30 or higher (σ < 7.5 mm).

A TWO-LEVEL APPROACH FOR THE CROWD-BASED COLLECTION OF VEHICLES FROM 3D POINT CLOUDS

In this article, we present a two-level approach for the crowd-based collection of vehicles from 3D point clouds. In the first level, the crowdworkers are asked to identify the coarse positions of vehicles in 2D rasterized shadings that were derived from the 3D point cloud. In order to increase the quality of the results, we utilize the wisdom of the crowd principle which says that averaging multiple estimates of a group of individuals provides an outcome that is often better than most of the underlying estimates or even better than the best estimate. For this, each crowd job is duplicated 10 times and the multiple results are integrated with a DBSCAN cluster algorithm. In the second level, we use the integrated results as pre-information for extracting small subsets of the 3D point cloud that are then presented to crowdworkers for approximating the included vehicle by means of a Minimum Bounding Box (MBB). Again, the crowd jobs are duplicated 10 times and an average bounding box is calculated from the individual bounding boxes. We will discuss the quality of the results of both steps and show that the wisdom of the crowd significantly improves the completeness as well as the geometric quality. With a tenfold acquisition, we have achieve a completeness of 93.3 percent and a geometric deviation of less than 1 m for 95 percent of the collected vehicles.