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

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.

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

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-1-w4-227-2015 ◽

2015 ◽

Vol XL-1/W4 ◽

pp. 227-232 ◽

Cited By ~ 2

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. 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. 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.

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A LIGHT-WEIGHT LASER SCANNER FOR UAV APPLICATIONS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b1-711-2016 ◽

2016 ◽

Vol XLI-B1 ◽

pp. 711-715 ◽

Cited By ~ 1

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.

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A LIGHT-WEIGHT LASER SCANNER FOR UAV APPLICATIONS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b1-711-2016 ◽

2016 ◽

Vol XLI-B1 ◽

pp. 711-715 ◽

Cited By ~ 1

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

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Spatial Accuracy of UAV-Derived Orthoimagery and Topography: Comparing Photogrammetric Models Processed with Direct Geo-Referencing and Ground Control Points

GEOMATICA ◽

10.5623/cig2016-102 ◽

2016 ◽

Vol 70 (1) ◽

pp. 21-30 ◽

Cited By ~ 41

Author(s):

Chris Hugenholtz ◽

Owen Brown ◽

Jordan Walker ◽

Thomas Barchyn ◽

Paul Nesbit ◽

...

Keyword(s):

Satellite System ◽

Base Station ◽

Measurement Unit ◽

Ground Control ◽

Lower Grade ◽

Control Points ◽

Gps Receiver ◽

Spatial Accuracy ◽

Ground Control Points ◽

Mean Square Errors

Mapping with unmanned aerial vehicles (UAVs) typically involves the deployment of ground control points (GCPs) to georeference the images and topographic model. An alternative approach is direct geo ref er encing, whereby the onboard Global Navigation Satellite System (GNSS) and inertial measurement unit are used without GCPs to locate and orient the data. This study compares the spatial accuracy of these approaches using two nearly identical UAVs. The onboard GNSS is the one difference between them, as one vehicle uses a survey-grade GNSS/RTK receiver (RTK UAV), while the other uses a lower-grade GPS receiver (non-RTK UAV). Field testing was performed at a gravel pit, with all ground measurements and aerial sur vey ing completed on the same day. Three sets of orthoimages and DSMs were produced for comparing spa tial accuracies: two sets were created by direct georeferencing images from the RTK UAV and non-RTK UAV and one set was created by using GCPs during the external orientation of the non-RTK UAV images. Spatial accuracy was determined from the horizontal (X,Y) and vertical (Z) residuals and root-mean-square-errors (RMSE) relative to 17 horizontal and 180 vertical check points measured with a GNSS/RTK base station and rover. For the two direct georeferencing datasets, the horizontal and vertical accuracy improved substantially with the survey-grade GNSS/RTK receiver onboard the RTK UAV, effectively reducing the RMSE values in X, Y and Z by 1 to 2 orders of magnitude compared to the lower grade GPS receiver onboard the non-RTK UAV. Importantly, the horizontal accuracy of the RTK UAV data processed via direct georeferencing was equivalent to the horizontal accuracy of the non-RTK UAV data processed with GCPs, but the vertical error of the DSM from the RTK UAV data was 2 to 3 times greater than the DSM from the non-RTK data with GCPs. Overall, results suggest that direct georeferencing with the RTK UAV can achieve horizontal accuracy comparable to that obtained with a network of GCPs, but for topographic meas urements requiring the highest achievable accuracy, researchers and practitioners should use GCPs.

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

Bulletin of Marine and Coastal Research ◽

10.25268/bimc.invemar.2010.39.1.138 ◽

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.

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mapKITE: A NEW PARADIGM FOR SIMULTANEOUS AERIAL AND TERRESTRIAL GEODATA ACQUISITION AND MAPPING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b1-957-2016 ◽

2016 ◽

Vol XLI-B1 ◽

pp. 957-962

Author(s):

P. Molina ◽

M. Blázquez ◽

J. Sastre ◽

I. Colomina

Keyword(s):

Real Time ◽

Unmanned Aircraft ◽

Ground Control ◽

Control Points ◽

The European Union ◽

New Paradigm ◽

Integrated Sensor ◽

Horizon 2020 ◽

Ground Control Points ◽

Sensor Orientation

We introduce a new mobile, simultaneous terrestrial and aerial, geodata collection and post-processing method: mapKITE. By combining two mapping technologies such as terrestrial mobile mapping and unmanned aircraft aerial mapping, geodata are simultaneously acquired from air and ground. More in detail, a mapKITE geodata acquisition system consists on an unmanned aircraft and a terrestrial vehicle, which hosts the ground control station. By means of a real-time navigation system on the terrestrial vehicle, real-time waypoints are sent to the aircraft from the ground. By doing so, the aircraft is linked to the terrestrial vehicle through a “virtual tether,” acting as a “mapping kite.” In the article, we entail the concept of mapKITE as well as the various technologies and techniques involved, from aircraft guidance and navigation based on IMU and GNSS, optical cameras for mapping and tracking, sensor orientation and calibration, etc. Moreover, we report of a new measurement introduced in mapKITE, that is, point-and-scale photogrammetric measurements [of image coordinates and scale] for optical targets of known size installed on the ground vehicle roof. By means of accurate posteriori trajectory determination of the terrestrial vehicle, mapKITE benefits then from kinematic ground control points which are photogrametrically observed by point-and-scale measures. Initial results for simulated configurations show that these measurements added to the usual Integrated Sensor Orientation ones reduce or even eliminate the need of conventional ground control points –therefore, lowering mission costs– and enable selfcalibration of the unmanned aircraft interior orientation parameters in corridor configurations, in contrast to the situation of traditional corridor configurations. Finally, we report about current developments of the first mapKITE prototype, developed under the European Union Research and Innovation programme Horizon 2020. The first mapKITE mission will be held at the BCN Drone Center (Collsuspina, Moià, Spain) in mid 2016.

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PRECISION ANALYSIS OF POINT-AND-SCALE PHOTOGRAMMETRIC MEASUREMENTS FOR CORRIDOR MAPPING: PRELIMINARY RESULTS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-3-w4-85-2016 ◽

2016 ◽

Vol XL-3/W4 ◽

pp. 85-90 ◽

Cited By ~ 2

Author(s):

P. Molina ◽

M. Blázquez ◽

J. Sastre ◽

I. Colomina

Keyword(s):

Unmanned Aircraft ◽

Ground Control ◽

Control Points ◽

Post Processing ◽

Single Pass ◽

Preliminary Results ◽

Ground Control Points ◽

Sensor Orientation ◽

Calibration Pattern ◽

Key Aspects

This paper addresses the key aspects of the sensor orientation and calibration approach within the mapKITE concept for corridor mapping, focusing on the contribution analysis of point-and-scale measurements of kinematic ground control points. MapKITE is a new mobile, simultaneous terrestrial and aerial, geodata acquisition and post-processing method. On one hand, the acquisition system is a tandem composed of a terrestrial mobile mapping system and an unmanned aerial system, the latter equipped with a remote sensing payload, and linked through a 'virtual tether', that is, a real-time waypoint supply from the terrestrial vehicle to the unmanned aircraft. On the other hand, mapKITE entails a method for geodata post-processing (specifically, sensor orientation and calibration) based on the described acquisition paradigm, focusing on few key aspects: the particular geometric relationship of a mapKITE network – the aerial vehicle always observes the terrestrial one as they both move –, precise air and ground trajectory determination – the terrestrial vehicle is regarded as a kinematic ground control point – and new photogrammetric measurements – pointing on and measuring the scale of an optical target on the roof of the terrestrial vehicle – are exploited. In this paper, we analyze the performance of aerial image orientation and calibration in mapKITE for corridor mapping, which is the natural application niche of mapKITE, based on the principles and procedures of integrated sensor orientation with the addition of point-and-scale photogrammetric measurements of the kinematic ground control points. To do so, traditional (static ground control points, photogrammetric tie points, aerial control) and new (pointing-and-scaling of kinematic ground control points) measurements have been simulated for mapKITE corridor mapping missions, consisting on takeoff and calibration pattern, single-pass corridor operation potentially performing calibration patterns, and landing and calibration pattern. Our preliminary results show that the exterior orientation, interior orientation and tie points precision estimates are better when using kinematic control with few static ground control, and even with excluding the latter. We conclude then that mapKITE can be a breakthrough on the UAS-based corridor mapping field, as precision requirements can be achieved for single-pass operation with no need for traditional static ground control points.

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

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w10-175-2019 ◽

2019 ◽

Vol XLII-2/W10 ◽

pp. 175-180 ◽

Cited By ~ 3

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

Abstract. 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.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.

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

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-5-w2-85-2019 ◽

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

Abstract. 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.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.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.

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

Journal of Geography Environment and Earth Science International ◽

10.9734/jgeesi/2019/v23i130161 ◽

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.

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