scholarly journals GEO-REGISTERING CONSECUTIVE DATASETS BY MEANS OF A REFERENCE DATASET, ELIMINATING GROUND CONTROL POINT INDICATION

2019 ◽  
Vol XLII-5/W2 ◽  
pp. 85-91
Author(s):  
S. Vincke ◽  
M. Vergauwen
Keyword(s):  
Reference System ◽  
Laser Scanning ◽  
Control Point ◽  
Ground Control ◽  
Test Case ◽  
Second Phase ◽  
Construction Site ◽  
Reference Dataset ◽  
Ground Control Points ◽  
Additional Input

<p><strong>Abstract.</strong> The architecture, engineering and construction (AEC) industry’s interest in more advanced ways of regular monitoring of construction site activities and the achieved building progress has been rising recently. This requires frequent recordings of the area. This is only feasible if the profound observations only require limited time, both for the actual capturing on-site as well as processing of the recorded data. Moreover, for monitoring purposes, it is vital that all datasets use a single, unique reference system. This allows for an easy comparison of various observations to determine both building progress as well as possible construction deviations or errors.</p><p>In this work, a framework is proposed that facilitates a faster and more efficient way of co-registering or geo-registering consecutive datasets. It comprises three major stages, starting with the capturing of the surroundings of the construction site. By thoroughly adding numerous ground control points (GCPs) in a second phase, the processed result of this input data can be considered as a reference dataset. In a third stage, this known component is used as additional input for the processing of subsequently captured datasets. Using overlapping areas, the new observations can be immediately transferred to the correct reference system. This eliminates the indication of GCPs in subsequent datasets, which is known to be time-consuming and error-prone.</p><p>Although in this work the focus of the proposed framework lies on a photogrammetric recording approach, it also is applicable for laser scanning. Its potential is showcased on a real-world apartment construction site in Ghent, Belgium. In the test case, the presented approach is shown to be efficient, with comparable accuracies as other current methods, however, requiring less time and effort.</p>

scholarly journals Corridor Mapping of Sandy Coastal Foredunes with UAS Photogrammetry and Mobile Laser Scanning

2019 ◽  
Vol 11 (11) ◽  
pp. 1352 ◽  
Author(s):  
Alphonse Nahon ◽  
Pere Molina ◽  
Marta Blázquez ◽  
Jennifer Simeon ◽  
Sylvain Capo ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Management Practices ◽  
Control Point ◽  
Unmanned Aircraft ◽  
Ground Control ◽  
Scanning System ◽  
Control Points ◽  
Ground Control Points ◽  
Spatial Coverage ◽  
Mean Square Errors

Recurrent monitoring of sandy beaches and of the dunes behind them is needed to improve the scientific knowledge on their dynamics as well as to develop sustainable management practices of those valuable landforms. Unmanned Aircraft Systems (UAS) are sought as a means to fulfill this need, especially leveraged by photogrammetric and LiDAR-based mapping methods and technology. The present study compares different strategies to carry UAS photogrammetric corridor mapping over linear extensions of sandy shores. In particular, we present results on the coupling of a UAS with a mobile laser scanning system, operating simultaneously in Cap Ferret, SW France. This aerial-terrestrial tandem enables terrain reconstruction with kinematic ground control points, thus largely avoiding the deployment of surveyed ground control points on the non-stable sandy ground. Results show how these three techniques—mobile laser scanning, photogrammetry based on ground control points, and photogrammetry based on kinematic ground control points—deliver accurate (i.e., root mean square errors < 15 cm) 3D reconstruction of beach-to-dune transition areas, the latter being performed at lower survey and logistic costs, and with enhanced spatial coverage capabilities. This study opens the gate for exploring longer (hundreds of kilometers) shoreline dynamics with ground-control-point-free air and ground mapping techniques.

scholarly journals A METHOD FOR SIMULTANEOUS AERIAL AND TERRESTRIAL GEODATA ACQUISITION FOR CORRIDOR MAPPING

2015 ◽  
Vol XL-1/W4 ◽  
pp. 227-232 ◽  
Author(s):  
P. Molina ◽  
M. Blázquez ◽  
J. Sastre ◽  
I. Colomina
Keyword(s):  
Spatial Configuration ◽  
Critical Role ◽  
Control Point ◽  
Unmanned Aircraft ◽  
Ground Control ◽  
Control Points ◽  
Post Processing ◽  
Simultaneous Operation ◽  
Ground Control Points ◽  
Sensor Orientation

In this paper, we present mapKITE, a new mobile, simultaneous terrestrial and aerial, geodata collection and post-processing method. On one side, the method combines a terrestrial mobile mapping system (TMMS) with an unmanned aerial mapping one, both equipped with remote sensing payloads (at least, a nadir-looking visible-band camera in the UA) by means of which aerial and terrestrial geodata are acquired simultaneously. This tandem geodata acquisition system is based on a terrestrial vehicle (TV) and on an unmanned aircraft (UA) linked by a 'virtual tether', that is, a mechanism based on the real-time supply of UA waypoints by the TV. By means of the TV-to-UA tether, the UA follows the TV keeping a specific relative TV-to-UA spatial configuration enabling the simultaneous operation of both systems to obtain highly redundant and complementary geodata. <br><br> On the other side, mapKITE presents a novel concept for geodata post-processing favoured by the rich geometrical aspects derived from the mapKITE tandem simultaneous operation. The approach followed for sensor orientation and calibration of the aerial images captured by the UA inherits the principles of Integrated Sensor Orientation (ISO) and adds the pointing-and-scaling photogrammetric measurement of a distinctive element observed in every UA image, which is a coded target mounted on the roof of the TV. By means of the TV navigation system, the orientation of the TV coded target is performed and used in the post-processing UA image orientation approach as a Kinematic Ground Control Point (KGCP). The geometric strength of a mapKITE ISO network is therefore high as it counts with the traditional tie point image measurements, static ground control points, kinematic aerial control and the new point-and-scale measurements of the KGCPs. With such a geometry, reliable system and sensor orientation and calibration and eventual further reduction of the number of traditional ground control points is feasible. <br><br> The different technical concepts, challenges and breakthroughs behind mapKITE are presented in this paper, such as the TV-to-UA virtual tether and the use of KGCP measurements for UA sensor orientation. In addition, the use in mapKITE of new European GNSS signals such as the Galileo E5 AltBOC is discussed. Because of the critical role of GNSS technologies and the potential impact on the corridor mapping market, the European Commission and the European GNSS Agency, in the frame of the European Union Framework Programme for Research and Innovation “Horizon 2020,” have recently awarded the “mapKITE” project to an international consortium of organizations coordinated by GeoNumerics S.L.

scholarly journals DESARROLLO DE UNA METODOLOGÍA SENCILLA PARA LA GEORREFERENCIACIÓN Y MEDICIÓN DE DISTANCIAS A PARTIR DE IMÁGENES DE SATÉLITE SISTEMÁTICAMENTE GEORREFERENCIADAS

2016 ◽  
Vol 39 (1) ◽  
Author(s):  
Leonardo Gónima ◽  
Libardo E. Ruiz ◽  
Marcos E. González
Keyword(s):  
Satellite Images ◽  
Control Point ◽  
Ground Control ◽  
Gps Data ◽  
Control Points ◽  
Statistical Validation ◽  
Distance Measurements ◽  
The North ◽  
Ground Control Points ◽  
Representative Points

One of the main problems for a precise georeferencing and distance measurements from satellite images, especially in geographical zones with strong morphologic and environmental dynamics, lies not only in the difficulty for identifying ground control points (GCPs), but also in real limitations for accessing such places. In this work a relatively simple methodology is proposed for georeferencing and distance measuring from satellite images, based on the utilization of previously calculated reflectance images from the surface and then oriented toward the north (systematic georeferencing). From these images and setting a basic control point (pixel) P, measured with GPS, the other GCPs were obtained by measurements of distances defined from the P point to representative points (pixels) on the image, selected for its georeferencing. The statistical validation of the obtained results, using a different sample of GCPs measured with GPS, shows that the precision of the georeferencing and distance measurement utilizing the developed methodology is similar to that obtained by conventional procedures, such as image georeferencing from GPS data.

scholarly journals A LIGHT-WEIGHT LASER SCANNER FOR UAV APPLICATIONS

2016 ◽  
Vol XLI-B1 ◽  
pp. 711-715 ◽  
Author(s):  
A. M. G. Tommaselli ◽  
F. M. Torres
Keyword(s):  
Laser Scanning ◽  
Cost Benefit ◽  
Ground Control ◽  
Raspberry Pi ◽  
Weight System ◽  
Scanning System ◽  
Light Weight ◽  
Control Points ◽  
Ground Control Points ◽  
Flight Height

Unmanned Aerial Vehicles (UAV) have been recognized as a tool for geospatial data acquisition due to their flexibility and favourable cost benefit ratio. The practical use of laser scanning devices on-board UAVs is also developing with new experimental and commercial systems. This paper describes a light-weight laser scanning system composed of an IbeoLux scanner, an Inertial Navigation System Span-IGM-S1, from Novatel, a Raspberry PI portable computer, which records data from both systems and an octopter UAV. The performance of this light-weight system was assessed both for accuracy and with respect to point density, using Ground Control Points (GCP) as reference. Two flights were performed with the UAV octopter carrying the equipment. In the first trial, the flight height was 100 m with six strips over a parking area. The second trial was carried out over an urban park with some buildings and artificial targets serving as reference Ground Control Points. In this experiment a flight height of 70 m was chosen to improve target response. Accuracy was assessed based on control points the coordinates of which were measured in the field. Results showed that vertical accuracy with this prototype is around 30 cm, which is acceptable for forest applications but this accuracy can be improved using further refinements in direct georeferencing and in the system calibration.

scholarly journals PRECISION POTENTIAL OF UNDERWATER NETWORKS FOR ARCHAEOLOGICAL EXCAVATION THROUGH TRILATERATION AND PHOTOGRAMMETRY

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 175-180 ◽  
Author(s):  
D. Skarlatos ◽  
F. Menna ◽  
E. Nocerino ◽  
P. Agrafiotis
Keyword(s):  
Standard Deviation ◽  
Structure From Motion ◽  
Control Point ◽  
Archaeological Site ◽  
3D Models ◽  
Ground Control ◽  
Control Points ◽  
Archaeological Excavation ◽  
Control Networks ◽  
Ground Control Points

<p><strong>Abstract.</strong> Given the rise and wide adoption of Structure from Motion (SfM) and Multi View Stereo (MVS) in underwater archaeology, this paper investigates the optimal option for surveying ground control point networks. Such networks are the essential framework for coregistration of photogrammetric 3D models acquired in different epochs, and consecutive archaeological related study and analysis. Above the water, on land, coordinates of ground control points are determined with geodetic methods and are considered often definitive. Other survey works are then derived from by using those coordinates as fixed (being ground control points coordinates considered of much higher precision). For this reason, equipment of proven precision is used with methods that not only compute the most correct values (according to the least squares principle) but also provide numerical measures of their precisions and reliability. Under the water, there are two options for surveying such control networks: trilateration and photogrammetry, with the former being the choice of the majority of archaeological expeditions so far. It has been adopted because of ease of implementation and under the assumption that it is more reliable and precise than photogrammetry.</p><p>This work aims at investigating the precision of network establishment by both methodologies by comparing them in a typical underwater archaeological site. Photogrammetric data were acquired and analysed, while the trilateration data were simulated under certain assumptions. Direct comparison of standard deviation values of both methodologies reveals a clear advantage of photogrammetry in the vertical (Z) axis and three times better results in horizontal precision.</p>

scholarly journals EVALUATION OF A METRIC CAMERA SYSTEM TAILORED FOR HIGH PRECISION UAV APPLICATIONS

2016 ◽  
Vol XLI-B1 ◽  
pp. 901-907 ◽  
Author(s):  
T. Kraft ◽  
M. Geßner ◽  
H. Meißner ◽  
M. Cramer ◽  
M. Gerke ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Aerial Survey ◽  
Ground Control ◽  
Test Case ◽  
Test Field ◽  
Control Points ◽  
Camera System ◽  
Ground Control Points ◽  
Industrial Grade ◽  
Static Conditions

In this paper we present the further evaluation of DLR’s modular airborne camera system MACS-Micro for small unmanned aerial vehicle (UAV). The main focus is on standardized calibration procedures and on photogrammetric workflows. The current prototype consists of an industrial grade frame imaging camera with 12 megapixel resolutions and a compact GNSS/IMU solution which are operated by an embedded computing unit (CPU). The camera was calibrated once pre-flight and several times post-flight over a period of 5 month using a three dimensional test field. The verification of the radiometric quality of the acquired images has been done under controlled static conditions and kinematic conditions testing different demosaicing methods. The validation of MACS-Micro is done by comparing a traditional photogrammetric evaluation with the workflows of Agisoft Photoscan and Pix4D Mapper. The analyses are based on an aerial survey of an urban environment using precise ground control points and acquired GNSS observations. Aerial triangulations with different configuratrions of ground control points (GCP’s) had been calculated, comparing the results of using a camera self-calibration and introducing fixed interior orientation parameters for Agisoft and Pix4D. The results are promising concerning the metric characteristics of the used camera and achieved accuracies in this test case. Further aspects have to be evaluated by further expanded test scenarios.

scholarly journals UAV ONBOARD GPS IN POSITIONING DETERMINATION

2016 ◽  
Vol XLI-B1 ◽  
pp. 1037-1042
Author(s):  
K. N. Tahar ◽  
S. S. Kamarudin
Keyword(s):  
Coordinate System ◽  
Global Positioning System ◽  
Large Scale ◽  
Control Point ◽  
Critical Issue ◽  
Ground Control ◽  
Positioning System ◽  
Ground Control Points ◽  
Global Positioning ◽  
Point Positioning

The establishment of ground control points is a critical issue in mapping field, especially for large scale mapping. The fast and rapid technique for ground control point’s establishment is very important for small budget projects. UAV onboard GPS has the ability to determine the point positioning. The objective of this research is to assess the accuracy of unmanned aerial vehicle onboard global positioning system in positioning determination. Therefore, this research used UAV onboard GPS as an alternative to determine the point positioning at the selected area. UAV is one of the powerful tools for data acquisition and it is used in many applications all over the world. This research concentrates on the error contributed from the UAV onboard GPS during observation. There are several points that have been used to study the pattern of positioning error. All errors were analyzed in world geodetic system 84- coordinate system, which is the basic coordinate system used by the global positioning system. Based on this research, the result of UAV onboard GPS positioning could be used in ground control point establishment with the specific error. In conclusion, accurate GCP establishment could be achieved using UAV onboard GPS by applying a specific correction based on this research.

scholarly journals Geospatial Analysis of Groundwater Potential Zones in Keffi, Nassarawa State, Nigeria

2019 ◽  
pp. 1-16
Author(s):  
D. R. Abdullahi ◽  
O. O. Oladosu ◽  
S. A. Samson ◽  
L. O. Abegunde ◽  
T. A. Balogun ◽  
...  
Keyword(s):  
Spatial Data ◽  
Control Point ◽  
Drainage Density ◽  
Groundwater Potential ◽  
Ground Control ◽  
Control Points ◽  
Groundwater Potential Zones ◽  
Ground Control Points ◽  
Potential Map ◽  
Groundwater Potential Map

Aim: Employ the use of Remote Sensing and Geographic Information System (GIS) to analyze areas of groundwater potentials in Keffi LGA to meet the rate of water demand. Study Design:  The study is designed to delineate and analyze the drainage characteristics, and map out the groundwater potential zones. Place and Duration of Study: The study is conducted in Keffi LGA of Nassarawa State, Nigeria in 2018. Methodology: Both spatial and non-spatial data were utilized for this research, including Ground Control Points, satellite imageries, and maps. The data generated consisting of the rainfall, NDVI, lineament, geology, slope, and relief were prepared into thematic layers and used for the generation of the drainage morphometric parameters and multi-criteria overlay analysis. Each of the layer used has inputs were ranked based on their relative importance in controlling groundwater potential, and divided into classes using the hydro-geological properties. The groundwater potential analysis reveals four distinct zones representing high, moderate, less and least groundwater potential zones. The delineated groundwater potential map was verified using the available Ground Control Point of boreholes across the study area. Results: The drainage of the study area falls in the 4th order, with the drainage density ranging from 0.2 to 1.6. From the groundwater potential map generated using the rainfall, lineament, geology, drainage density, slope, soil, and NDVI attributes, areas categorized having the moderate groundwater potentials cover about 89.1 km2, while the least cover 0.1 km2 of the study area.  Validating the result with borehole locations across the location shows that the boreholes are dug based on the availability of water following the groundwater potentials, and; 59.8% of the settlement area falls within the moderate groundwater potential classes. Conclusion: The area has adequate capacity for water supply, and only those within the high groundwater potential classes can access groundwater throughout the year.

Highway Cross-Slope Measurement using Mobile LiDAR

2018 ◽  
Vol 2672 (39) ◽  
pp. 88-97 ◽  
Author(s):  
Alireza Shams ◽  
Wayne A. Sarasua ◽  
Afshin Famili ◽  
William J. Davis ◽  
Jennifer H. Ogle ◽  
...  
Keyword(s):  
South Carolina ◽  
Laser Scanning ◽  
Effective Means ◽  
Cost Effective ◽  
Measurement Unit ◽  
Ground Control ◽  
Lidar Data ◽  
Ground Control Points ◽  
South Carolina Department ◽  
The Difference

Ensuring adequate pavement cross-slope on highways can improve driver safety by reducing the potential for ponding to occur or vehicles to hydroplane. Mobile laser scanning (MLS) systems provide a rapid, continuous, and cost-effective means of collecting accurate 3D coordinate data along a corridor in the form of a point cloud. This study provides an evaluation of MLS systems in terms of the accuracy and precision of collected cross-slope data and documentation of procedures needed to calibrate, collect, and process this data. Mobile light detection and ranging (LiDAR) data were collected by five different vendors on three roadway sections. The results indicate the difference between ground control adjusted and unadjusted LiDAR derived cross-slopes, and field surveying measurements less than 0.19% at a 95% confidence level. The unadjusted LiDAR data incorporated corrections from an integrated inertial measurement unit and high-accuracy real-time kinematic GPS, however it was not post-processed adjusted with ground control points. This level of accuracy meets suggested cross-slope accuracies for mobile measurements (±0.2%) and demonstrates that mobile LiDAR is a reliable method for cross-slope verification. Performing cross-slope verification can ensure existing pavement meets minimum cross-slope requirements, and conversely is useful in identifying roadway sections that do not meet minimum standards, which is more desirable than through crash reconnaissance where hydroplaning was evident. Adoption of MLS would enable the South Carolina Department of Transportation (SCDOT) to address cross-slope issues through efficient and accurate data collection methods.

scholarly journals ARE MEASURED GROUND CONTROL POINTS STILL REQUIRED IN UAV BASED LARGE SCALE MAPPING? ASSESSING THE POSITIONAL ACCURACY OF AN RTK MULTI-ROTOR PLATFORM

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 507-514 ◽  
Author(s):  
L. Teppati Losè ◽  
F. Chiabrando ◽  
F. Giulio Tonolo
Keyword(s):  
Large Scale ◽  
Control Point ◽  
Satellite System ◽  
Added Value ◽  
Ground Control ◽  
Positional Accuracy ◽  
Ground Control Points ◽  
Aerial Vehicle ◽  
Global Navigation Satellite ◽  
The Impact

Abstract. The estimate of External Orientation (E.O.) parameters for a block of images is a crucial step in the photogrammetric pipeline and the most demanding in terms of required time and human effort, both during the fieldwork and post-processing phases. Different researchers developed strategies to minimize the impact of this phase. Despite the achievement of good results, it was not possible until now to completely cancel the effect of this step. However, the efforts of the researchers in these years have also been devoted to the implementation of direct photogrammetry strategies, in order to almost completely automate the E.O. of the photogrammetric block. These new approaches were made possible also thanks to the latest developments of commercial UAVs, especially in terms of the installed GPS/GNSS (Global Positioning System/Global Navigation Satellite System) hardware. The aim of this manuscript is to evaluate the different perspectives and issues connected with the deployment of a UAV (Unmanned Aerial Vehicle) equipped with a multi-frequency GPS/GNSS receiver. Starting from the considerations mentioned above and leveraging previous works based on a fixed-wing platform, the focus of this contribution is the assessment of the real performances of an RTK multi-rotor platform addressing several questions. Is it possible to generate added-value products with centimetre 3D accuracies without measuring any ground control point? Which are the operational requirements to be taken into account in the planning phase? Are consolidated UAV mapping operational workflows already available to enable a robust direct georeferencing approach?

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