ABSTRACT:One of the most important aspects of documenting cultural heritage sites is acquiring detailed and accurate data. A popular method of storing 3D information about historical structures is using 3D models. These models are built based on terrestrial or aerial laser scanning data. These methods are seldom used together. Historical buildings usually have a very complex design, therefore the input data, on the basis of which their 3D models are being built, must provide a high enough accuracy to model these complexities. The data processing methods used, as well as the modeling algorithms implemented, should be highly automated and universal. The main of the presented research was to analyze and compare various methods for extracting matching points. The article presents the results of combining data from ALS and TLS using reference points extracted both manually and automatically. Finally, the publication also includes an analysis of the accuracy of the data merging process.
Mini multispectral sensors are an insufficient source of imagery to perform appropriate analyses, due to the low spatial resolution of imagery. Therefore, in many cases it is necessary to conduct data fusion. However, using common pansharpening methods may not be sufficient. Therefore, the authors propose a new method for processing and sharpening multispectral data acquired with a mini multispectral camera, for mapping purposes, especially in flooded areas and flood plains, in rapid time. The proposed algorithm of sharpening is based on the use of the decorrelation process of multispectral images and their transformation to the YCBCR color space, where the luminance component is converted to the blue band of the high resolution image and then an inverse transformation to the RGB color space is performed, resulting in imagery with a high spatial and spectral resolution. The results of our research were compared with pansharpened multispectral images generated using classical methods: IHS, PCA, Brovey, Ehlers, wavelet and multiplicative transforms. Moreover, an assessment of a quality of the sharpened spectral images by determining: R-RMSE, ERGAS and Q Index indicators was performed.
The aim of this research was to assess the possibility of conducting an absolute orientation procedure for video imagery, in which the external orientation for the first image was typical for aerial photogrammetry whereas the external orientation of the second was typical for terrestrial photogrammetry. Starting from the collinearity equations, assuming that the camera tilt angle is equal to 90°, a simplified mathematical model is proposed. The proposed method can be used to determine the X, Y, Z coordinates of points based on a set of collinearity equations of a pair of images. The use of simplified collinearity equations can considerably shorten the processing tine of image data from Unmanned Aerial Vehicles (UAVs), especially in low cost systems. The conducted experiments have shown that it is possible to carry out a complete photogrammetric project of an architectural structure using a camera tilted 85°–90° (φ or ω) and simplified collinearity equations. It is also concluded that there is a correlation between the speed of the UAV and the discrepancy between the established and actual camera tilt angles.
ABSTRACT:The archaeological heritage is non-renewable, and any invasive research or other actions leading to the intervention of mechanical or chemical into the ground lead to the destruction of the archaeological site in whole or in part. For this reason, modern archeology is looking for alternative methods of non-destructive and non-invasive methods of new objects identification. The concept of aerial archeology is relation between the presence of the archaeological site in the particular localization, and the phenomena that in the same place can be observed on the terrain surface form airborne platform. One of the most appreciated, moreover, extremely precise, methods of such measurements is airborne laser scanning. In research airborne laser scanning point cloud with a density of 5 points/sq. m was used. Additionally unmanned aerial vehicle imagery data was acquired. Test area is located in central Europe. The preliminary verification of potentially microstructures localization was the creation of digital terrain and surface models. These models gave an information about the differences in elevation, as well as regular shapes and sizes that can be related to the former settlement/sub-surface feature. The paper presents the results of the detection of potentially sub-surface microstructure fields in the forestry area.
In the ISPRS final report from 2012 it was accented that light and low cost Unmanned Aerial Vehicles are playing a more and more important role when it comes to carrying remote sensing and photogrammetric sensors. Such platforms are characterized by a small weight, low cost of purchase and later exploitation and, depending on their technical specifications, a payload of about 1,5 kg. The above characteristics make these platforms an attractive alternative for carrying sensors in comparison to a traditional airplane, especially whilst conducting photogrammetric and remote sensing studies of small areas. However because of the size and mass of such UAV's, data acquired by means of the sensors which they carry is characterized by very dynamically changing in time exterior orientation parameters. In extreme cases this can cause no forward overlap between subsequent frames which makes such data, in most circumstances, useless. An interesting solution is using a video camera (or a number of video cameras) as a sensor. Such cameras enable, depending on the standard of registration, the acquisition of tens of images every second, which means a very large forward overlap. The article contains the analyses of the possibility of using the FCO HD 1080i and FCO HD 720i video cameras as a UAV sensor. Each of the analyzed cameras is different in terms of their build, as well as the quality of the acquired imagery, however that all have the same low weight. An evaluation was made in two different aspects: geometrical and photographic. Based on specialized test fields it was possible to determine the exterior orientation parameters ofthese cameras which allowed for an analysis of their invariability. Other parameters which had been determined and analyzed include: the spatial resolution, the way in which colours are registered and aberrations which were present within the optics of these cameras.
Textured three dimensional models are currently the one of the standard methods of representing the results of photogrammetric works. A realistic 3D model combines the geometrical relations between the structure's elements with realistic textures of each of its elements. Data used to create 3D models of structures can be derived from many different sources. The most commonly used tool for documentation purposes, is a digital camera and nowadays terrestrial laser scanning (TLS). Integration of data acquired from different sources allows modelling and visualization of 3D models historical structures. Additional aspect of data integration is possibility of complementing of missing points for example in point clouds. The paper shows the possibility of integrating data from terrestrial laser scanning with digital imagery and an analysis of the accuracy of the presented methods. The paper describes results obtained from raw data consisting of a point cloud measured using terrestrial laser scanning acquired from a Leica ScanStation2 and digital imagery taken using a Kodak DCS Pro 14N camera. The studied structure is the ruins of the Ilza castle in Poland.
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