TRANSFORMATION ET AJUSTEMENT DES COORDONNEES D’UNE BANDE PAR CALCUL ELECTRONIQUE

1961 ◽  
Vol 15 (10) ◽  
pp. 574-580 ◽  
Author(s):  
G. H. Schut
Keyword(s):  
Research Council ◽  
Three Dimensional ◽  
National Research Council ◽  
Control Points ◽  
Two Dimensional ◽  
Ground Control Points ◽  
Mechanical Methods ◽  
Electronic Computers ◽  
Operating Instructions ◽  
Second Degree

Strip triangulation is carried out for the purpose of increasing by photogrammetric means the number of available ground control points. The triangulation must be followed by a transformation which brings the points from the strip-coordinate system to the required geodetic system. The transformation includes an adjustment when redundant points are used to increase the accuracy of the positioning and when systematic errors must be corrected for in the strip triangulation. Numerical methods of transformation and adjustment have an inherently greater accuracy. If electronic computers are used, they are also more economical than comparable graphical or mechanical methods. The following programs have been coded for the IBM-650 by the Photogrammetric Section of the National Research Council of Canada: (a) a program for three-dimensional linear conformai transformation, employing formulas (1a) and (1b), (b) a program for two-dimensional conformai transformation of horizontal coordinates, employing either the linear formulas (8) or the formulas of the second degree (10), (c) a program for two-dimensional conformai transformation of the third degree with the possibility of conversion to the fourth and fifth degree, (d) a program for transformation of horizontal coordinates of a block of overlapping strips by second-degree conformai transformations, and (e) a program for the last-mentioned transformation by third-degree conformai transformations. These programs and operating instructions can be made available for serious applicants from the National Research Council.

scholarly journals IMPROVING UAV TELEMETRY POSITIONING FOR DIRECT PHOTOGRAMMETRY

2021 ◽  
Vol XLIII-B2-2021 ◽  
pp. 61-68
Author(s):  
L. Rossi ◽  
F. Ioli ◽  
E. Capizzi ◽  
L. Pinto ◽  
M. Reguzzoni
Keyword(s):  
Low Cost ◽  
Three Dimensional ◽  
Control Points ◽  
Three Dimensional Model ◽  
Commercial Software ◽  
Ground Control Points ◽  
Lower Accuracy ◽  
Least Squares Adjustment ◽  
Gnss Receivers

Abstract. A fundamental step of UAV photogrammetric processes is to collect Ground Control Points (GCPs) by means of geodetic-quality GNSS receivers or total stations, thus obtaining an absolutely oriented model with a centimetric accuracy. This procedure is usually time-consuming, expensive and potentially dangerous for operators who sometimes need to reach inaccessible areas. UAVs equipped with low-cost GNSS/IMU sensors can provide information about position and attitude of the images. This telemetry information is not enough for a photogrammetric restitution with a centimetric accuracy, but it can be usefully exploited when a lower accuracy is required. The algorithm proposed in this paper aims at improving the quality of this information, in order to introduce it into a direct-photogrammetric process, without collecting GCPs. In particular, the estimation of an optimal trajectory is obtained by combining the camera positions derived from UAV telemetry and from the relative orientation of the acquired images, by means of a least squares adjustment. Then, the resulting trajectory is used as a direct observation of the camera positions into a commercial software, thus replacing the information of GCPs. The algorithm has been tested on different datasets, comparing the classical photogrammetric solution (with GCPs) with the proposed one. These case-studies showed that using the improved trajectory as input to the commercial software (without GCPs) the reconstruction of the three-dimensional model can be improved with respect to the solution computed by using the UAV raw telemetry only.

scholarly journals A Fast, Three-Dimensional, Indirect Geolocation Method Using IAGM and DSM Data without GCPs for Spaceborne SAR Images

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5062
Author(s):  
Liu ◽  
Xiao
Keyword(s):  
Corner Point ◽  
Three Dimensional ◽  
Surface Model ◽  
Control Points ◽  
Sar Image ◽  
Sar Images ◽  
Ground Control Points ◽  
The Earth ◽  
Proportional Relationship ◽  
Geolocation Accuracy

To determine the geolocation of a pixel for spaceborne synthetic aperture radar (SAR) images, traditional indirect geolocation methods can cause great computational complexity. In this paper, a fast, three-dimensional, indirect geolocation method without ground control points (GCPs) is presented. First, the Range-Doppler (RD) geolocation model with all the equations in the Earth-centered rotating (ECR) coordinate system is introduced. By using an iterative analytical geolocation method (IAGM), the corner point locations of a quadrangle SAR image on the Earth’s surface are obtained. Then, a three-dimensional (3D) grid can be built by utilizing the digital surface model (DSM) data in this quadrangle. Through the proportional relationship for every pixel in the 3D grid, the azimuth time can be estimated, which is the key to decreasing the calculation time of the Doppler centroid. The results show that the proposed method is about 12 times faster than the traditional method, and that it maintains geolocation accuracy. After acquiring the precise azimuth time, it is easy to obtain the range location. Therefore, the spaceborne SAR image can be geolocated to the Earth surface precisely based on the high-resolution DSM data.

scholarly journals Assessing the Accuracy of Digital Surface Models Derived from Optical Imagery Acquired with Unmanned Aerial Systems

Drones ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 15 ◽  
Author(s):  
Salvatore Manfreda ◽  
Petr Dvorak ◽  
Jana Mullerova ◽  
Sorin Herban ◽  
Pietro Vuono ◽  
...  
Keyword(s):  
3D Model ◽  
Low Cost ◽  
Three Dimensional ◽  
Careful Consideration ◽  
Ground Control ◽  
Unmanned Aerial Systems ◽  
Control Points ◽  
Earthen Dam ◽  
Ground Control Points ◽  
Aerial Systems

Small unmanned aerial systems (UASs) equipped with an optical camera are a cost-effective strategy for topographic surveys. These low-cost UASs can provide useful information for three-dimensional (3D) reconstruction even if they are equipped with a low-quality navigation system. To ensure the production of high-quality topographic models, careful consideration of the flight mode and proper distribution of ground control points are required. To this end, a commercial UAS was adopted to monitor a small earthen dam using different combinations of flight configurations and by adopting a variable number of ground control points (GCPs). The results highlight that optimization of both the choice and combination of flight plans can reduce the relative error of the 3D model to within two meters without the need to include GCPs. However, the use of GCPs greatly improved the quality of the topographic survey, reducing error to the order of a few centimeters. The combined use of images extracted from two flights, one with a camera mounted at nadir and the second with a 20° angle, was found to be beneficial for increasing the overall accuracy of the 3D model and especially the vertical precision.

An Interpolation Method for Strip Adjustment

1966 ◽  
Vol 20 (1) ◽  
pp. 23-32
Author(s):  
J. Somogyi*
Keyword(s):  
Interpolation Method ◽  
Three Dimensional ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
The Individual

This paper describes a method of strip adjustment by means of linear three-dimensional transformations applied to the individual models. The first and the last model are transformed independently, using at least three ground-control points. The intermediate models are transformed in a manner that minimizes the jumps in scale, azimuth and tilt, and enforces the fit at intermediate ground-control points. Coordinate connections are made at the centers of gravity of the carryover points. The results of the adjustment of two short strips of 11 and 12 models are shown.

THE USE OF POLYNOMIALS IN THE THREE-DIMENSIONAL ADJUSTMENT OF TRIANGULATED STRIPS

1962 ◽  
Vol 16 (3) ◽  
pp. 132-136 ◽  
Author(s):  
G. H. Schut
Keyword(s):  
Research Council ◽  
Three Dimensional ◽  
National Research Council ◽  
Two Dimensions ◽  
Conformal Transformations ◽  
Present Issue

The treatment of this subject in recent publications is discussed. The procedure described by M. Perks in the present issue of THE CANADIAN SURVEYOR is found to be the most accurate, but it is more complicated than it need be. The procedure adopted at the National Research Council of Canada is then described. This makes use of a sequence of conformal transformations in two dimensions. It has the same accuracy as Perks’s procedure, but it is simpler in both formulation and use.

Establishment of High Precision Horizontal and Vertical Control Network in Zoucheng City

2013 ◽  
Vol 864-867 ◽  
pp. 2787-2791
Author(s):  
De Bao Wang ◽  
Yong Xiang Liu ◽  
Wen Jing Yang
Keyword(s):  
Fourth Order ◽  
Function Method ◽  
Three Dimensional ◽  
Geodetic Network ◽  
Control Network ◽  
Control Points ◽  
Two Dimensional ◽  
Level Control ◽  
Vertical Control ◽  
Free Network

The paper uses D level, E level and the level of GPS control network establishment satellite space geodetic network in Zoucheng city, through the baseline calculating, classic adjustment of free network, three-dimensional unconstrained adjustment and two-dimensional constraint adjustment to get the WGS-84 three dimensional coordinates and 1980 xi 'an horizontal coordinates of control points; then using the fourth-order levelling connection survey all D-level and part E-level control points to build vertical control network, for the remaining GPS control points we utilize quadric function method using GPS elevation fitting given its elevation seek to obtain three-dimensional coordinates of all the basic control points.

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 PRELIMINARY GAOFEN-3 INSAR DEM ACCURACY ANALYSIS

2018 ◽  
Vol XLII-3 ◽  
pp. 173-177
Author(s):  
Q. Chen ◽  
T. Li ◽  
X. Tang ◽  
X. Gao ◽  
X. Zhang
Keyword(s):  
Three Dimensional ◽  
Ground Control ◽  
Calibration Model ◽  
Control Points ◽  
Error Sources ◽  
Alpine Regions ◽  
Ground Control Points ◽  
Range Function ◽  
Interferometric Phase ◽  
Dem Accuracy

GF-3 satellite, the first C band and full-polarization SAR satellite of China with spatial resolution of 1 m, was successfully launched in August 2016. We analyze the error sources of GF-3 satellite in this paper, and provide the interferometric calibration model based on range function, Doppler shift equation and interferometric phase function, and interferometric parameters calibrated using the three-dimensional coordinates of ground control points. Then, we conduct the experimental two pairs of images in fine stripmap I mode covering Songshan of Henan Province and Tangshan of Hebei Province, respectively. The DEM data are assessed using SRTM DEM, ICESat-GLAS points, and ground control points database obtained using ZY-3 satellite to validate the accuracy of DEM elevation. The experimental results show that the accuracy of DEM extracted from GF-3 satellite SAR data can meet the requirements of topographic mapping in mountain and alpine regions at the scale of 1 : 50000 in China. Besides, it proves that GF-3 satellite has the potential of interferometry.

scholarly journals Impact of UAV Surveying Parameters on Mixed Urban Landuse Surface Modelling

2020 ◽  
Vol 9 (11) ◽  
pp. 656
Author(s):  
Muhammad Hamid Chaudhry ◽  
Anuar Ahmad ◽  
Qudsia Gulzar
Keyword(s):  
Point Cloud ◽  
Large Scale ◽  
Accuracy Assessment ◽  
Computational Cost ◽  
Three Dimensional ◽  
Point Clouds ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
High Computational Cost

Unmanned Aerial Vehicles (UAVs) as a surveying tool are mainly characterized by a large amount of data and high computational cost. This research investigates the use of a small amount of data with less computational cost for more accurate three-dimensional (3D) photogrammetric products by manipulating UAV surveying parameters such as flight lines pattern and image overlap percentages. Sixteen photogrammetric projects with perpendicular flight plans and a variation of 55% to 85% side and forward overlap were processed in Pix4DMapper. For UAV data georeferencing and accuracy assessment, 10 Ground Control Points (GCPs) and 18 Check Points (CPs) were used. Comparative analysis was done by incorporating the median of tie points, the number of 3D point cloud, horizontal/vertical Root Mean Square Error (RMSE), and large-scale topographic variations. The results show that an increased forward overlap also increases the median of the tie points, and an increase in both side and forward overlap results in the increased number of point clouds. The horizontal accuracy of 16 projects varies from ±0.13m to ±0.17m whereas the vertical accuracy varies from ± 0.09 m to ± 0.32 m. However, the lowest vertical RMSE value was not for highest overlap percentage. The tradeoff among UAV surveying parameters can result in high accuracy products with less computational cost.

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