Accurate three-dimensional (3D) data from indoor spaces are of high importance for various applications in construction, indoor navigation and real estate management. Mobile scanning techniques are offering an efficient way to produce point clouds, but with a lower accuracy than the traditional terrestrial laser scanning (TLS). In this paper, we first tackle the problem of how the quality of a point cloud should be rigorously evaluated. Previous evaluations typically operate on some point cloud subset, using a manually-given length scale, which would perhaps describe the ranging precision or the properties of the environment. Instead, the metrics that we propose perform the quality evaluation to the full point cloud and over all of the length scales, revealing the method precision along with some possible problems related to the point clouds, such as outliers, over-completeness and misregistration. The proposed methods are used to evaluate the end product point clouds of some of the latest methods. In detail, point clouds are obtained from five commercial indoor mapping systems, Matterport, NavVis, Zebedee, Stencil and Leica Pegasus: Backpack, and three research prototypes, Aalto VILMA , FGI Slammer and the Würzburg backpack. These are compared against survey-grade TLS point clouds captured from three distinct test sites that each have different properties. Based on the presented experimental findings, we discuss the properties of the proposed metrics and the strengths and weaknesses of the above mapping systems and then suggest directions for future research.

Detailed modeling of floodplain flows and associated processes requires data on mixed, heterogeneous vegetation at river reach scale, though the collection of vegetation data is typically limited in resolution or lack spatial information. This study investigates physically-based characterization of mixed floodplain vegetation by means of terrestrial laser scanning (TLS). The work aimed at developing an approach for deriving the characteristic reference areas of herbaceous and foliated woody vegetation, and estimating the vertical distribution of woody vegetation. Detailed experimental data on vegetation properties were gathered both in a floodplain site for herbaceous vegetation, and under laboratory conditions for 2-3 m tall trees. The total plant area (Atot) of woody vegetation correlated linearly with the TLS-based voxel count, whereas the Atot of herbaceous vegetation showed a linear correlation with TLS-based vegetation mean height. For woody vegetation, 1 cm voxel size was found suitable for estimating both the Atot and its vertical distribution. A new concept was proposed for deriving Atot for larger areas from the point cloud attributes of small sub-areas. The results indicated that the relationships between the TLS attributes and Atot of the sub-areas can be derived either by mm resolution TLS or by manual vegetation sampling. OPEN ACCESSWater 2015, 7 421

Abstract:A novel approach to evaluating night-time road and street environment lighting conditions through 3D point clouds is presented. The combination of luminance imaging and 3D point cloud acquired with a terrestrial laser scanner was used for analyzing 3D luminance on the road surface. A calculation of the luminance (cd/m 2 ) was based on the RGB output values of a Nikon D800E digital still camera. The camera was calibrated with a reference luminance source. The relative orientation between the luminance images and intensity image of the 3D point cloud was solved in order to integrate the data sets into the same coordinate system. As a result, the 3D model of road environment luminance is illustrated and the ability to exploit the method for evaluating the luminance distribution on the road surface is presented. Furthermore, the limitations and future prospects of the methodology are addressed. The method provides promising results for studying road lighting conditions OPEN ACCESSRemote Sens. 2015, 7 11390in future lighting optimizations. The paper presents the methodology and its experimental application on a road section which consists of five luminaires installed on one side of a two-lane road in Otaniemi, Espoo, Finland.

Mobile mapping systems (MMSs) are used for mapping topographic and urban features which are difficult and time consuming to measure with other instruments. The benefits of MMSs include efficient data collection and versatile usability. This paper investigates the data processing steps and quality of a boat-based mobile mapping system (BoMMS) data for generating terrain and vegetation points in a river environment. Our aim in data processing was to filter noise points, detect shorelines as well as points below water surface and conduct ground point classification. Previous studies of BoMMS have investigated elevation accuracies and usability in detection of fluvial erosion and deposition areas. The new findings concerning BoMMS data are that the improved data processing approach allows for identification of multipath reflections and shoreline delineation. We demonstrate the possibility to measure bathymetry data in shallow (0–1 m) and clear water. Furthermore, we evaluate for the first time the accuracy of the BoMMS ground points classification compared to manually classified data. We also demonstrate the spatial variations of the ground point density and assess elevation and vertical accuracies of the BoMMS data.

The detailed geometry of ground topography is needed for various environmental studies, including river dynamic studies (erosion/deposition), hydraulic modeling, interpreting fluvial geomorphology and habitat modeling. In recent years, mobile laser scanning (MLS) has provided an efficient and versatile method for collecting three-dimensional data for built and natural environments. MLS is a surveying technique that uses a laser beam for distance observations, global navigation satellite systems (GNSS) for determining the position and an accurate inertial measurement unit (IMU) for measuring the 3D orientation. The MLS system can be flexibility mounted on different vehicles for different purposes. Advances in technology in recent years have introduced lighter sensors, which have also made it possible to develop personal laser scanning (PLS) systems by mounting the sensors on a backpack.While ground topography mapping using MLS has mainly been discussed in the context of road modeling, the performance and usability of MLS have been lacking in geomorphological surveys and fluvial studies. In particular, a multitemporal MLS data collection yields a remarkable and highly detailed data source for analysing different natural processes. The multitemporal MLS surveys provide possible new applications for e.g. flood risk management, monitoring the health and the quality of city trees, conducting environmental impact assessments, updating the city maps and updating interior models.In this PhD thesis, the feasibility of MLS for mapping and monitoring a riverine environment was analysed. The MLS data were measured by mounting the sensors on a boat (BoMMS), cart and backpack. The assessment of digital terrain model (DTM) accuracy and the geometric quality of MLS point clouds and performance of BoMMS data for monitoring multitemporal topography and vegetation changes were likewise investigated. Automatic data processing methods were tested and presented for generating terrain and vegetation points from the BoMMS data. Moreover, the study demonstrated the integrated use of MLS and panoramic images for interpreting an MLS-based change detection model.The results indicate that MLS is an efficient method for improving the spatial and temporal coverage of high-resolution 3D environmental models. In particular, MLS provide a unique measuring perspective for complex environments. While the number of applications can be unlimited, it should be noted that high-performance MLS measurements require good satellite visibility, proper system calibration and reference control measurements. TiivistelmäMaastonmuotojen yksityiskohtainen geometria on tärkeä lähtötieto monissa ympäristö-tutkimuksissa, kuten jokivarsien muutosseurannassa, hydraulisessa mallinnuksessa, geomorfologian tulkinnassa ja elinympäristöjen mallinnuksessa. Viime vuosina liikkuva laserkeilaus on osoittautunut tehokkaaksi ja monikäyttöiseksi menetelmäksi kerätä 3D-tietoa sekä rakennetuista että luonnon ympäristöistä. Liikkuva laserkeilaus on mittaustekniikka, joka hy...