scholarly journals Influence of the shape and size of the ground targets on the accuracy of photogrammetric processing

2020 ◽  
Vol 28 (3) ◽  
pp. 293-304
Author(s):  
Amr Elsheshtawy ◽  
Larisa A. Gavrilova ◽  
Anatoly N. Limonov ◽  
Mohamed Elshewy

The materials obtained from the unmanned aerial vehicle (UAV) are used to solve many problems, including large-scale mapping and monitoring of linear objects, as well as the ecological situation and monitoring of emergency situations. The promptly obtained photographic materials make it possible to reveal the consequences of man-made human impact associated with degradation of the soil cover, flooding of lands, salinization and pollution of the soil layer, and changes in the vegetation cover. Control points are used for absolute orientation of the generated models in the most projects of photogrammetric processing of aerial photos and images obtained from UAVs. In areas with low contour, before aerial survey, targeting is carried out in the required zones. The research is devoted to the study of the influence of the shape of ground targets on the accuracy of photogrammetric processing. It involved three different types of ground targets located on the land cover along the survey path at a distance not exceeding 1 m from each other. The targets were used as ground control points in the photogrammetric processing of the materials from the UAV. Two three-stripe photographic surveys of the 900 m long track were carried out: with UAV DJI PHANTOM 4 PRO camera FC6310 at a scale of 1:3400 and ground resolution of 1 cm and with the DJI Mavic PRO UAV camera FC220 at a scale of 1:12 700 and ground resolution of 2 cm. In both cases, the direction of flight is north - south, 36 targets were included in the photogrammetric processing. In the first case, 502 images were processed, in the second - 152. The photogrammetric processing for the orthophoto mosaic generation was carried out using the Agisoft Photo Scan Professional software. Four different contrasting sites in the study area were selected for the study: green grass, dry grass, clay, sand. Accuracy was assessed according to two criteria: 1) the degree of visualization of the target on the images; 2) the accuracy of the orthophoto mosaic, generated using various targets.

Author(s):  
S. A. Kadnichansky ◽  
M. B. Kurkov ◽  
V. M. Kurkov ◽  
A. G. Chibunichev ◽  
L. K. Trubina

Abstract. Results of researches of calibration of the SONY CYBER-SHOT DSC-RX1RM2 camera on the basis of the test field aerial survey are given in article. Researches showed that calibration using aerial survey of a calibration test field provides reliable result with a required accuracy. Recommendations about execution of aerial survey and about creation of an operational test field for photogrammetric calibration of the camera before execution of the specific project are made. When aerial survey is carried out with GNSS determination of coordinates of the perspective centers of aerial photos with RMS of coordinates no more than 0.08 m it is possible to use the self-calibration mode for photogrammetric network block adjustment without ground control points. At the same time accuracy of the end result of photogrammetric processing commensurable with an accuracy, achieved with ground control points, is provided.


2021 ◽  
Vol 47 (2) ◽  
pp. 96-103
Author(s):  
Volodymyr Hlotov ◽  
Alla Hunina ◽  
Ihor Kolb ◽  
Vadim Kolesnichenko ◽  
Ihor Trevoho

The work aims to analyze and study the possibilities of using “Cetus” unmanned aerial vehicle (UAV) for performing topographic aerial surveys. The authors developed and tested aircraft-type UAV for topographic aerial photography. The studies were conducted on a specialized landfill, at which there is an appropriate number of situational points whose coordinates are determined with high accuracy. These points were used as both reference and control points. The obtained UAV aerial survey materials were subjected to a phototriangulation process to determine the orientation elements and to analyze, first and foremost, the angular orientation elements. The surveying was carried out on a mountainous territory, where the spatial coordinates of 37 situational points were determined by the method of ground-based GPS survey with an average accuracy of up to 0.05 m. These points were used as reference and control points. Aerial photography was performed in such a way that the scale of the images was as uniform as possible. The design solutions implemented in the Cetus UAV provide all the possibilities to perform aerial surveys of territories in strict compliance with the projected flight parameters. UAV equipment provides the necessary real-time correction of the position of the aerial camera. At the same time the optimum straightness of routes, stability of scales and mutual overlapping of pictures is reached. Regarding the accuracy of obtaining the spatial coordinates of the points of terrain objects, using “Cetus” UAV surveys, plans can even be made on a scale of even 1: 1000. As a result of the creation of the UAV “Cetus”, it became possible to perform the topographic aerial survey of the territories and to create large-scale orthophotos that fully meet the instructions. As a result of testing the “Cetus” UAV, it can be used in production processes when drawing up topographic plans for a large-scale series: 1: 1000 – 1: 5000, which will significantly save the cost of performing topographic work.


Author(s):  
F. Chiabrando ◽  
V. Di Pietra ◽  
A. Lingua ◽  
P. Maschio ◽  
F. Noardo ◽  
...  

(TLS, Terrestrial Laser Scanning), and large scale mapping derived by UAV (Unmanned Aerial Vehicle) survey. This paper refers an example of 3D survey and reality based modelling applied on landscape and architectural assets. The choice of methods for documentation, in terms of survey techniques, depends primarily on issues and features of the area. <br><br> The achieved experience, allow to consider that the easy handling of TLS has enabled the use in limited spaces among buildings and collapsed roofs, but the topographic measure of GCPs (Ground Control Points), neither by total station nor by GPS/RTK technique, was easily feasible. Even more than proving the ability of the integration of TLS and UAV photogrammetry to achieve a multi-source and multi-scale whole model of a village, the experience has been a test to experiment the registration of terrestrial clouds with the support of control points derived by UAV survey and finally, a comparison among different strategies of clouds registration is reported. Analysing for each approach a number of parameters (number of clouds registration, number of needed points, processing time, overall accuracy) the further comparisons have been achieved. <br><br> The test revealed that it is possible to decrease the large number of terrestrial control points when their determination by topographical measures is difficult, and it is possible to combine the techniques not only for the integration of the final 3Dmodel, but also to solve and make the initial stage of the drafting process more effective.


Author(s):  
F. Chiabrando ◽  
V. Di Pietra ◽  
A. Lingua ◽  
P. Maschio ◽  
F. Noardo ◽  
...  

(TLS, Terrestrial Laser Scanning), and large scale mapping derived by UAV (Unmanned Aerial Vehicle) survey. This paper refers an example of 3D survey and reality based modelling applied on landscape and architectural assets. The choice of methods for documentation, in terms of survey techniques, depends primarily on issues and features of the area. <br><br> The achieved experience, allow to consider that the easy handling of TLS has enabled the use in limited spaces among buildings and collapsed roofs, but the topographic measure of GCPs (Ground Control Points), neither by total station nor by GPS/RTK technique, was easily feasible. Even more than proving the ability of the integration of TLS and UAV photogrammetry to achieve a multi-source and multi-scale whole model of a village, the experience has been a test to experiment the registration of terrestrial clouds with the support of control points derived by UAV survey and finally, a comparison among different strategies of clouds registration is reported. Analysing for each approach a number of parameters (number of clouds registration, number of needed points, processing time, overall accuracy) the further comparisons have been achieved. <br><br> The test revealed that it is possible to decrease the large number of terrestrial control points when their determination by topographical measures is difficult, and it is possible to combine the techniques not only for the integration of the final 3Dmodel, but also to solve and make the initial stage of the drafting process more effective.


Author(s):  
Wu Bo-Yi ◽  
Zhang Ning ◽  
Su Guo-Zhong

Based on the theoretic analysis of the accuracy in large scale photogrammetric mapping, some defects in traditional procedure were discussed. A set of key technologies dedicate to accuracy improvement in low altitude photogrammetry were analyzed in detail, namely the utilization of wide angle camera and low altitude flight, enhancement in image matching, predesigned layout of Ground Control Points (GCPs) in field survey, optimization of adjustment model and improvement in map processing. Besides, a low altitude aerial unmanned airship system was established. Finally, successful implementation in 1:500 topographic mapping project in built-up areas of 30 counties in Shanxi Province proves the practicability and effectiveness of the proposed approaches.


The recent progress for spatial resolution of remote sensing imagery led to generate many types of Very HighResolution (VHR) satellite images, consequently, general speaking, it is possible to prepare accurate base map larger than 1:10,000 scale. One of these VHR satellite image is WorldView-3 sensor that launched in August 2014. The resolution of 0.31m makes WorldView-3 the highest resolution commercial satellite in the world. In the current research, a pan-sharpen image from that type, covering an area at Giza Governorate in Egypt, used to determine the suitable large-scale map that could be produced from that image. To reach this objective, two different sources for acquiring Ground Control Points (GCPs). Firstly, very accurate field measurements using GPS and secondly, Web Map Service (WMS) server (in the current research is Google Earth) which is considered a good alternative when GCPs are not available, are used. Accordingly, three scenarios are tested, using the same set of both 16 Ground Control Points (GCPs) as well as 14 Check Points (CHKs), used for evaluation the accuracy of geometric correction of that type of images. First approach using both GCPs and CHKs coordinates acquired by GPS. Second approach using GCPs coordinates acquired by Google Earth and CHKs acquired by GPS. Third approach using GCPs and CHKs coordinates by Google Earth. Results showed that, first approach gives Root Mean Square Error (RMSE) planimeteric discrepancy for GCPs of 0.45m and RMSE planimeteric discrepancy for CHKs of 0.69m. Second approach gives RMSE for GCPs of 1.10m and RMSE for CHKs of 1.75m. Third approach gives RMSE for GCPs of 1.10m and RMSE for CHKs of 1.40m. Taking map accuracy specification of 0.5mm of map scale, the worst values for CHKs points (1.75m&1,4m) resulted from using Google Earth as a source, gives the possibility of producing 1:5000 large-scale map compared with the best value of (0.69m) (map scale 1:2500). This means, for the given parameters of the current research, large scale maps could be produced using Google Earth, in case of GCPs are not available accurately from the field surveying, which is very useful for many users.


2020 ◽  
Author(s):  
Ji Won Suh ◽  
William Ouimet

&lt;p&gt;Orthomosaics from aerial photographs play a pivotal role in understanding land-use/land cover in broad area and the advent of image processing technology allows us to produce orthoimagery. However, recent advanced technologies are seldom applied to produce historical orthophotos from early or mid 20C old aerial photos in broad extent since they have limited information (e.g. camera position, flying altitude, and yaw) which is critical information for orthomosaics. In this context, this study aims to orthomosaic and georectify historical aerial photographs and validate the horizontal accuracy of orthomosacicked outputs. In order to achieve this, firstly, we collected 117 aerial photographs of 1934 (scale 1:12,000) and 68 of 1951 (scale 1:20,000) from UConn air photo achieve focused on Woodstock town in Connecticut, USA. Secondly, we created GCPs (Ground Control Points) as referenced points where they have not changed over time by overlaying multiple datasets such as LiDAR DEM, hillshade map, recent orthoimagery. Thirdly, we align photos with Control Points (CPs), build a mesh, and build orthomosaics of 1934 and 1951, respectively, using Agisoft Photoscan 1.5. Lastly, calculating RMSE (Root Mean Square Error) and offsets comparing between set of GCPs and CPs from Lidar DEM and set of them digitized from orthomosaics. As a result, RMSE values of GCPs and CPs between 1934 and 1951 mostly show that output of this work is acceptable to use for standard mapping and GIS work or visualization based on ASPRS 1990 horizonal accuracy standard. In addition, we found several factors affect horizontal accuracy of orthomosaics; resolution of aerial photos, spatial distribution of GCPs and CPs, the number of CPs and GCPs, the percentage of lateral overlapping area along flight strips, and margin area. Overall, applying automated orthomosaicking image processing to historical aerial photographs has the potential to represent historical landscape and even detect its change in broad extent.&lt;/p&gt;


Author(s):  
W. Tampubolon ◽  
W. Reinhardt

During disaster and emergency situations, geospatial data plays an important role to serve as a framework for decision support system. As one component of basic geospatial data, large scale topographical maps are mandatory in order to enable geospatial analysis within quite a number of societal challenges. <br><br> The increasing role of geo-information in disaster management nowadays consequently needs to include geospatial aspects on its analysis. Therefore different geospatial datasets can be combined in order to produce reliable geospatial analysis especially in the context of disaster preparedness and emergency response. A very well-known issue in this context is the fast delivery of geospatial relevant data which is expressed by the term “Rapid Mapping”. <br><br> Unmanned Aerial Vehicle (UAV) is the rising geospatial data platform nowadays that can be attractive for modelling and monitoring the disaster area with a low cost and timely acquisition in such critical period of time. Disaster-related object extraction is of special interest for many applications. <br><br> In this paper, UAV-borne data has been used for supporting rapid mapping activities in combination with high resolution airborne Interferometric Synthetic Aperture Radar (IFSAR) data. A real disaster instance from 2013 in conjunction with Mount Sinabung eruption, Northern Sumatra, Indonesia, is used as the benchmark test for the rapid mapping activities presented in this paper. On this context, the reliable IFSAR dataset from airborne data acquisition in 2011 has been used as a comparable dataset for accuracy investigation and assessment purpose in 3 D reconstructions. After all, this paper presents a proper geo-referencing and feature extraction method of UAV data to support rapid mapping activities.


2014 ◽  
Vol 70 (5) ◽  
Author(s):  
Norhadija Darwin ◽  
Anuar Ahmad ◽  
Wan Abdul Aziz Wan Mohd Akib

Unmanned Aerial Vehicle (UAV) system offers many advantages in several applications such as topographic mapping, thematic mapping, slope mapping, geohazard studies, monitoring, etc. This study utilizes UAV system for large scale mapping by using a digital camera attached to a fixed wing UAV. The main objective of this study is to explore the potential of UAV for large scale mapping and to evaluate the accuracy of the photogrammetric output produced from the UAV system. The UAV was used to acquire low altitude aerial photograph based on photogrammetric technique and subsequently accuracy assessment is performed. The Ground Control Points (GCPs) and Check Points (CPs) were established using GPS rapid static technique for photogrammetric data processing. The GCPs were used in to produce 3D stereomodel and other photogrammetric output while the CP is used for accuracy assessment. For digital image processing of the aerial photograph and map production, Erdas Imagine 8.6 software is employed. For accuracy assessment, the coordinates of the selected points in the 3D stereomodel were compared to the conjugate points observed using GPS and the root mean square error (RMSE) is computed. From this study, the results showed that the achievable RMSE are ± 0.510 m, ± 0.564 m and ± 0.622 m for coordinates X, Y and Z respectively. For this study, the digital map was also produced using the photogrammetric technique and it is compared with an engineering plan produced from ground surveying technique (i.e. total station). From this study, it can be concluded that accuracy of sub-meter is achieved using the UAV system. Also, this study demonstrates that the UAV system has the potential for large scale mapping in the field of surveying and other diversified applications, especially for small area, minimum budget and less manpower. 


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