Aaltodoc Repository :: Browsing by Author "Vaaja, Matti Tapio"

Browsing by Author "Vaaja, Matti Tapio"

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3D Point Cloud Data in Conveying Information for Local Green Factor Assessment
(MDPI AG, 2021-11-11) Jaalama, Kaisa; Kauhanen, Heikki; Keitaanniemi, Aino; Rantanen, Toni; Virtanen, Juho-Pekka; Julin, Arttu; Vaaja, Matti Tapio; Ingman, Matias; Ahlavuo, Marika; Hyyppä, Hannu; MeMo; Geoinformatics; Department of Built Environment
The importance of ensuring the adequacy of urban ecosystem services and green infrastructure has been widely highlighted in multidisciplinary research. Meanwhile, the consolidation of cities has been a dominant trend in urban development and has led to the development and implementation of the green factor tool in cities such as Berlin, Melbourne, and Helsinki. In this study, elements of the green factor tool were monitored with laser-scanned and photogrammetrically derived point cloud datasets encompassing a yard in Espoo, Finland. The results show that with the support of 3D point clouds, it is possible to support the monitoring of the local green infrastructure, including elements of smaller size in green areas and yards. However, point clouds generated by distinct means have differing abilities in conveying information on green elements, and canopy covers, for example, might hinder these abilities. Additionally, some green factor elements are more promising for 3D measurement-based monitoring than others,such as those with clear geometrical form. The results encourage the involvement of 3D measuring technologies for monitoring local urban green infrastructure (UGI), also of small scale.
Applying photogrammetry to reconstruct 3D luminance point clouds of indoor environments
(Earthscan, 2022-01-02) Kurkela, Matti; Maksimainen, Mikko; Julin, Arttu; Virtanen, Juho-Pekka; Männistö, Ilari; Vaaja, Matti Tapio; Hyyppä, Hannu; Department of Built Environment; MeMo; Geoinformatics
Computer-aided 3D modelling is the standard design method in the architecture, engineering, construction, owner, operator (AECOO) industry and in lighting design. Applying a photogrammetric process, a sequence of images is used to reconstruct the geometry of a space or an object in a 3D model. Likewise, a calibrated digital camera is utilized to measure the surface luminance values of an environment or an object. We propose a workflow in which the geometry and the luminance values are measured simultaneously by combining these two measurement methods. The pipeline has been assessed and validated through the application to a case study, the Aalto Hall (Aalto University, Espoo, Finland), in order to understand its potential.
Drift analysis and sectional post-processing of indoor simultaneous localization and mapping (SLAM)-based laser scanning data
(Elsevier, 2023-03) Keitaanniemi, Aino; Rönnholm, Petri; Kukko, Antero; Vaaja, Matti Tapio; Department of Built Environment; Geoinformatics; MeMo
Even though the SLAM laser scanners (LSs) have the required resolution for construction analysis, a drift error has been detected in georeferencing phase of the data processing. The reduction of drift error in SLAM LSs with third-party software has not been studied. This paper demonstrates the drift error behavior of commercial SLAM LSs and their correction with sectional post-processing methods, and shows that the drift error is mainly in a vertical direction, and it is largest in the middle of the trajectory. The drift error was reduced from 10.6 cm to 0.2 cm. Circa 30 s length sections have better results than larger sections with non-rigid transformation algorithm. The method has shown potential to improve the quality and cost-effectiveness of multitemporal construction documentation. In addition, locations of additional control points were analyzed to prevent drift error, with adjustments to the walking path.
Feasibility of mobile laser scanning for mapping and monitoring a riverine environment
(Aalto University, 2014) Vaaja, Matti Tapio; Hyyppä, Hannu, Prof., Aalto University, Department of Real Estate, Planning and Geoinformatics, Finland; Hyyppä, Juha, Prof., Finnish Geodetic Institute, Department of Remote Sensing and Photogrammetry, Finland.; Alho, Petteri, Prof., University of Turku, Department of Geography and Geology, Finland; Maankäyttötieteiden laitos; Department of Real Estate, Planning and Geoinformatics; Research Institute of Measuring and Modeling for the Built Environment; Insinööritieteiden korkeakoulu; School of Engineering; Haggrén, Henrik, Prof., Aalto University, Department of Real Estate, Planning and Geoinformatics, Finland
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.
Measurement Strategies for Street-Level SLAM Laser Scanning of Urban Environments
(Finnish Society of Geodesy and Photogrammetry and Geoinformatics research group, Aalto University School of Engineering, 2020) Keitaanniemi, Aino; Kukko, Antero; Virtanen, Juho-Pekka; Vaaja, Matti Tapio; Geoinformatics; MeMo; Department of Built Environment
Data collection for street-level mapping is currently executed with terrestrial (TLS) or mobile laser scanners (MLS). However, these methods have disadvantages such as TLS requiring a lot of time and MLS being dependent on the global navigation satellite system (GNSS) and an inertial measurement unit (IMU). These are not problems if we use simultaneous localization and mapping (SLAM) based laser scanners. We studied the utility of a SLAM ZEB-REVO scanner for mapping street-level objects in an urban environment by analyzing the geometric and visual differences with a TLS reference. In addition to this, we examined the influence of traffic on the measurement strategy. The results of the study showed that SLAM-based laser scanners can be used for street-level mapping. However, the measurement strategy affects the point clouds. The strategy of walking trajectory in loops produced a 2 cm RMS and 4-6 mm mode of error even in not optimal situations of the sensor in the urban environment. However, it was possible to get an RMS under 2.2 cm and a 32 cm mode of error with other measurement strategies.
Mobile laser scanning for mapping river point bars and banks
(2010) Vaaja, Matti Tapio; Hyyppä, Juha; Maanmittaustieteiden laitos; Insinööritieteiden korkeakoulu; School of Engineering; Haggren, Henrik
The M.Sc. thesis was part of the GIFLOOD project (Developing mapping and modelling approaches as a part of flood risk management business) funded by TEKES. One of the main aims in the project is to test and develop different kind of laser scanning models and combine them with other mapping data. Flood mapping and flood risk related business became an interesting topic in 2007, when the EU flood directive came into force. According to the directive member states are obligated for identify potential major flood zones and flood risks. The objective of the thesis was to investigate the performance of mobile laser scanning in river environment. Work included the accuracy assessment of mobile scanning based elevation models and developing of mobile scanning approach for change detection. The methods of change detection were height difference images and volume calculation. Furthermore, this work presents the background and principles of mobile mapping. The laser scanning data of this work were measured in the northern Lapland on river Pulmankijoki. Measurements were undertaken in late summer 2008 and 2009. The mobile mapping system, used in the study, was developed in co-operation with Helsinki University of Technology, Finnish Geodetic Institute and University of Turku. It was mounted on the boat and the cart in order to map river point bars and banks. The reference data were collected with the terrestrial laser scanner and GPS measurements. The RMS errors and standard deviations of mobile laser scanning in non-vegetated areas ranged between 2.3 - 17.6 cm and 2.3 - 7.6 cm. In river banks, where the ground surface was classified under the vegetation, the corresponding errors were 15.7 - 28.4 cm and 11.6 - 27.2 cm. The example of change detection demonstrates that the explanation degree of mobile scanning based height difference surface is 0.93 with corresponding terrestrial laser scanning surface. The mobile scanning data can be utilized in flood modelling, river dynamic studies and hydraulic modelling. Compared to traditional airborne laser scanning, mobile scanning suits better for mapping of small areas. Method can be used also to acquiring very precise multi-temporal data for change detection. The accuracy of mobile scanning system is almost in same level as terrestrial laser scanners. The biggest challenges are related to GPS positioning and data processing.
Morphological changes and riffle-pool dynamics related to flow in a meandering river channel based on a 5-year monitoring period using close-range remote sensing
(ELSEVIER SCIENCE BV, 2020-03-01) Salmela, Jouni; Kasvi, Elina; Vaaja, Matti Tapio; Kaartinen, Harri; Kukko, Antero; Jaakkola, Anttoni; Alho, Petteri; Department of Built Environment; Geoinformatics; MeMo; University of Turku; Gaze Inc.
The maintenance of riffle-pool sequences and morphological changes in the long-term have received little attention in the literature. The aims of this study are to determine morphological changes and riffle-pool maintenance in relation to flow conditions in a meandering river channel over a 5-yr period. Change detection was focused on riffle and pool maintenance in a river reach covering three successive meander bends. Changes in a meandering river channel were studied utilizing detailed digital terrain models and flow data. The results indicated that riffle-pool sequences are maintained by high discharge events and the development of pools and riffles was linked. During high discharges, the riverbed eroded on the concave sides and the inflexion points aggraded, causing riffle–pool sequences, whereas during low discharges, concave sides aggraded and inflexion points eroded, causing pool filling and riffle erosion. While discharge increased, near-bed flow velocities increased faster on the concave sides of the bends than at the inflexion points, becoming higher at a discharge of 8 m3/s, ~20% of the bankfull discharge. Changes in the three successive meander bends were mainly similar, and the geometry of meandering rivers contributed to the locations of riffles and pools. Pools and riffles were not stable in size and shape, but their longitudinal location remained the same, instead of migrating up and down the channel. Morphological changes occurred in meander bends year-round, but they were non-linear. Annual channel change was not similar from year to year owing to different flow regimes and morphological changes during the previous year. However, seasonal detection revealed similarities between high and low discharge periods between the years. Concave sides of meander bends may act to temporarily store sediment; however, storage is preserved only under the effective hydrological discharge.
Utilizing a Terrestrial Laser Scanner for 3D Luminance Measurement of Indoor Environments
(MDPI AG, 2021-05) Kurkela, Matti; Maksimainen, Mikko; Julin, Arttu; Rantanen, Toni; Virtanen, Juho-Pekka; Hyyppä, Juha; Vaaja, Matti Tapio; Hyyppä, Hannu; Department of Built Environment; MeMo; Geoinformatics
We aim to present a method to measure 3D luminance point clouds by applying the integrated high dynamic range (HDR) panoramic camera system of a terrestrial laser scanning (TLS) instrument for performing luminance measurements simultaneously with laser scanning. We present the luminance calibration of a laser scanner and assess the accuracy, color measurement properties, and dynamic range of luminance measurement achieved in the laboratory environment. In addition, we demonstrate the 3D luminance measuring process through a case study with a luminance-calibrated laser scanner. The presented method can be utilized directly as the luminance data source. A terrestrial laser scanner can be prepared, characterized, and calibrated to apply it to the simultaneous measurement of both geometry and luminance. We discuss the state and limitations of contemporary TLS technology for luminance measuring.

Browsing by Author "Vaaja, Matti Tapio"

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