Development of a 3D Viewer for georeferencing and monoplotting of historical terrestrial images.

2020 ◽  
Author(s):  
Sebastian Flöry ◽  
Camillo Ressl ◽  
Gerhard Puercher ◽  
Norbert Pfeifer ◽  
Markus Hollaus ◽  
...  
Keyword(s):  
Digital Terrain Model ◽  
Local Scale ◽  
Aerial Imagery ◽  
Ground Control ◽  
Control Points ◽  
Mountainous Regions ◽  
Terrain Model ◽  
Digital Terrain ◽  
Ground Control Points ◽  
Selection Of

<p>Mountain regions are disproportionately affected by global warming and changing precipitation conditions. Especially the strong variations within high mountain ranges at the local scale require additional sources in order to quantify changes within this challenging environment. With the emergence of alpine tourism, terrestrial photographs became available by the end of 1800, predating aerial imagery for the selected study areas by 50 years. Due to the earlier availability and oblique acquisition geometry these images are a promising source for quantifying changes within mountainous regions at the local scale. Within the research project SEHAG, methods to process these images and to analyse their potential to quantify and describe environmental changes are developed and applied to study areas in Austria and Italy.</p><p>One of the prerequisites for the estimation of changes based on terrestrial imagery is the calculation of the corresponding object point for each pixel in a global coordinate system resulting in a georeferenced orthorectified image. This can be achieved by intersecting the ray defined by the projection center of the camera and each pixel with a digital terrain model, a process known as monoplotting.</p><p>So far 1000 terrestrial images with unknown interior and exterior orientation have been collected from various archives for the selected study areas Kaunertal, Horlachtal (both Tyrol, Austria) and Martelltal (South Tyrol, Italy). In order to estimate all camera parameters a 3D viewer for the selection of ground control points has been developed and implemented. The estimation of the exterior and interior orientation is done in OrientAL. </p><p>Preliminary results for selected images show, that especially the developed 3D viewer is an important improvement for the selection of well distributed ground control points and the accurate estimation of the exterior and interior orientation. Monoplotting depends on a digital terrain model, which cannot be computed from the terrestrial images alone due to missing overlap and different acquisitions times. Hence, the combination with historical digital terrain models derived from aerial imagery is necessary to minimize errors introduced due to changes in topography until today. While the large amount of terrestrial images with their oblique acquisition geometries can be exploited to fill occluded areas by combining the results from multiple images, the partly missing or inaccurate temporal information poses another limitation.</p><p>With this large image collection, for the first time, we are able to evaluate the use of historical oblique terrestrial photographs for change detection in a systematic manner. This will promote knowledge about challenges, limitations and the achievable accuracy of monoplotting within mountainous regions. The work is part of the SEHAG project (project number I 4062) funded by the Austrian Science Fund (FWF).</p>

scholarly journals THE INFLUENCE OF GROUND CONTROL POINTS CONFIGURATION AND CAMERA CALIBRATION FOR DTM AND ORTHOMOSAIC GENERATION USING IMAGERY OBTAINED FROM A LOW-COST UAV

2020 ◽  
Vol V-1-2020 ◽  
pp. 239-244
Author(s):  
M. V. Y. Garcia ◽  
H. C. Oliveira
Keyword(s):  
Low Cost ◽  
Digital Terrain Model ◽  
Flying Height ◽  
Ground Control ◽  
Optimum Number ◽  
Control Points ◽  
Digital Products ◽  
Positional Accuracy ◽  
Terrain Model ◽  
Ground Control Points

Abstract. Technological improvement of Unmanned Aerial Vehicles (UAVs) and computer vision algorithms, such as Structured-from-Motion (SfM) and Multi-view Stereo (MVS) have provided the possibility for high-resolution mapping and high-density point cloud generation using low-cost equipment and sensors. Orthomosaics and Digital Terrain Model (DTM) are the main digital products considering mapping purposes. Their quality is directly related to the sensors boarded on the UAV and data processing. Ground Control Points (GCPs) are used in the process of indirect georeferencing and also to model the lens distortions. The number of GCPs used in this process affects the positional accuracy of the final products. This study aims to determine the optimum number of GCPs to achieve high accuracy orthomosaics and DTM. To obtain this optimum number, an area of 3.85 ha was mapped with a low-cost UAV DJI Phantom 4 Advanced at 31 m flying height, lateral and longitudinal overlap of 90% and 80%, respectively, and using 22 checkpoints for quality assessment. For the experiments, different configuration were used both for the number of GCPs and for the use of self-calibration process or pre-calibrated camera IOP (Interior Orientation Parameters). The results show that for the flight configuration used in this work and for the mentioned UAV, a total of 5 GCPs, with pre-calibrated camera IOP, yields an accuracy of 0.023 m for X, 0.031 m for Y and 0.033 m for Z.

scholarly journals DTM GENERATION WITH UAV BASED PHOTOGRAMMETRIC POINT CLOUD

2017 ◽  
Vol XLII-4/W6 ◽  
pp. 77-79 ◽  
Author(s):  
N. Polat ◽  
M. Uysal
Keyword(s):  
Low Cost ◽  
Laser Scanner ◽  
Digital Camera ◽  
Digital Terrain Model ◽  
Field Work ◽  
Generation Process ◽  
Control Points ◽  
Terrain Model ◽  
Digital Terrain ◽  
Ground Control Points

Nowadays Unmanned Aerial Vehicles (UAVs) are widely used in many applications for different purposes. Their benefits however are not entirely detected due to the integration capabilities of other equipment such as; digital camera, GPS, or laser scanner. The main scope of this paper is evaluating performance of cameras integrated UAV for geomatic applications by the way of Digital Terrain Model (DTM) generation in a small area. In this purpose, 7 ground control points are surveyed with RTK and 420 photographs are captured. Over 30 million georeferenced points were used in DTM generation process. Accuracy of the DTM was evaluated with 5 check points. The root mean square error is calculated as 17.1 cm for an altitude of 100 m. Besides, a LiDAR derived DTM is used as reference in order to calculate correlation. The UAV based DTM has o 94.5 % correlation with reference DTM. Outcomes of the study show that it is possible to use the UAV Photogrammetry data as map producing, surveying, and some other engineering applications with the advantages of low-cost, time conservation, and minimum field work.

Research on Algorithm of Delaunay Triangulation Net Interpolating the Best Point

2014 ◽  
Vol 1044-1045 ◽  
pp. 1278-1282
Author(s):  
Xing Guo Qiu ◽  
Zheng Liu
Keyword(s):  
Delaunay Triangulation ◽  
Complex Terrain ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Kriging Interpolation ◽  
Control Points ◽  
Interpolation Algorithm ◽  
Terrain Model ◽  
Digital Terrain ◽  
Technological Tool

Aiming at the folds caused by the sparse data in the process of DTM (Digital Terrain Model), this article proposed a method of interpolating spatial control points based on Delaunay triangulation and Kriging interpolation algorithm. The terrain data of an area with complex terrain in Xianyang was used to construct terrain model according to the proposed algorithm. Experimental results show that the method can finish the interpolation of the terrain denser data quickly and accurately, and it provides an efficient technological tool for building a true three-dimensional terrain model.

scholarly journals DTM GENERATION THROUGH UAV SURVEY WITH A FISHEYE CAMERA ON A VINEYARD

2018 ◽  
Vol XLII-2 ◽  
pp. 983-989 ◽  
Author(s):  
G. Ronchetti ◽  
D. Pagliari ◽  
G. Sona
Keyword(s):  
Precision Agriculture ◽  
Reference Model ◽  
Digital Terrain Model ◽  
Kriging Interpolation ◽  
Terrain Model ◽  
Digital Terrain ◽  
Ground Control Points ◽  
Agricultural Applications ◽  
Aerial Vehicle ◽  
Fisheye Camera

Precision agriculture recommends a sustainable employment of nutrients and water, according to the site-specific crop requirements. In this context, the knowledge of soil characteristics allows to appropriately manage resources. Even the topography can influence the spatial distribution of the water on a field. This work focuses on the production of high-resolution Digital Terrain Model (DTM) in agriculture by photogrammetric processing fisheye images, acquired with very light Unmanned Aerial Vehicle (UAV). Particular attention is given to the data processing procedures and to the assessment of the quality of the results, considering the peculiarity of the acquired images. An experimental test has been carried out on a vineyard located in Monzambano, Northern Italy, through photogrammetric survey with Parrot Bebop 2 UAV. It has been realized at the end of the vegetation season, to investigate the ground without any impediment due to the presence of leaves or branches. In addition, the survey has been used for evaluating the performance of Bebop fisheye camera in viticulture. Different flight strategies have been tested, together with different Ground Control Points (GCPs) and Check Points (CPs) configurations and software packages. The computed DTMs have been compared with a reference model obtained through Kriging interpolation of GNSS-RTK measurements. Residuals on CPs are of the order of 0.06 m, for all the considered scenarios, that for agricultural applications is by far sufficient. The photogrammetric DTMs show a good agreement with the reference one.

scholarly journals Evaluation On Different UAV’s Georeferencing Points to Generate Accurate Orthophoto and Digital Terrain Model

2021 ◽  
Vol 18 (2) ◽  
pp. 67
Author(s):  
MUHAMMAD HAFIZ AIZUDDIN BIN MOHD ZAIDI ◽  
Khairul Nizam Tahar
Keyword(s):  
Autonomous Navigation ◽  
Three Dimensional ◽  
Digital Terrain Model ◽  
Optimum Number ◽  
Terrain Model ◽  
Aerial Photogrammetry ◽  
Digital Terrain ◽  
Ground Control Points ◽  
Waypoint Navigation ◽  
User Friendly

UAV or drone application of autonomy ranging can be divided into several levels, from basic hovering and position over trajectory tracking and waypoint navigation to fully autonomous navigation. This study used the DroneDeploy application for an autonomous flight mission. It is the process of taking photographs from an aircraft or other flying objects with a camera mounted on them to produce a three-dimensional (3D) map from the images captured, including a digital terrain model (DTM) and orthophotos. As for this study, the same output will be generated, but different flight parameter applications were used. Therefore, the study determined the optimum number of ground control points (GCPs) and evaluated the accuracy of the final results for each flight design. Acquired data were processed using the Pix4D modeller software due to the user-friendly factor and faster processing rate offered by the software. The results were analysed, and recommendations were made for future study improvement and to avoid similar problems. This study is useful for the mapping industry to achieve high accuracy results.  Keywords: Aerial photogrammetry, Flight Parameter, UAV apps, DTM, Orthophotos, GCPs

scholarly journals ACCURACY ANALYSIS OF MEASURING CLOSE-RANGE IMAGE POINTS USING MANUAL AND STEREO MODES

2013 ◽  
Vol 39 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Jūratė Sužiedelytė-Visockienė
Keyword(s):  
3D Model ◽  
Digital Terrain Model ◽  
Image Point ◽  
Range Image ◽  
Control Points ◽  
Image Transformation ◽  
Terrain Model ◽  
Digital Terrain ◽  
Close Range ◽  
Manual Mode

The performed investigations are aimed at estimating the accuracy of image processing using different image point measurements. For this purpose, digital close-range images were processed applying photogrammetric software PhotoMod. The measurements have been made employing two methods: stereo and manual mode. Two or more overlapping images are matched when control and tie points are estimated. The images of two objects have been taken for experimental investigation. Control points and tie points were measured switching either to stereo or manual mode applying the required software. The control points of the first object are distributed on the surface of a smooth facade and on the surface of different (a few) levels. The process of image matching includes the calculation of the correlation coefficient, vertical parallax residuals and the root mean square of the object. Following image transformation (adjustment processes) to the created 3D model, the accuracy of the measured points is determined. All these values show the precision of close-range photogrammetric processes. Such accuracy satisfies requirements for creating a proper digital terrain model and orthophoto generation.

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