Orthomosaics of Historical Aerial Photographs and Horizontal Accuracy Analysis

2020 ◽  
Author(s):  
Ji Won Suh ◽  
William Ouimet
Keyword(s):  
Image Processing ◽  
Aerial Photographs ◽  
Control Points ◽  
Limited Information ◽  
Aerial Photos ◽  
Ground Control Points ◽  
Multiple Datasets ◽  
Standard Mapping ◽  
Lidar Dem ◽  
Air Photo

<p>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.</p>

scholarly journals Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images

2016 ◽  
Author(s):  
Joaquín M. C. Belart ◽  
Etienne Berthier ◽  
Eyjólfur Magnússon ◽  
Leif S. Anderson ◽  
Finnur Pálsson ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ground Control ◽  
Control Points ◽  
Stereo Images ◽  
Ice Cap ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Lidar Dem ◽  
Vertical Accuracy ◽  
Annual Time

Abstract. Sub-meter resolution satellite stereo images allow the generation of high resolution, accurate digital elevation models (DEMs). Repeated acquisitions of stereo images from Pléiades, in October 2014 and May 2015, and from WorldView2 (WV2), in February 2015, over Drangajökull ice cap (NW-Iceland) are used to estimate the geodetic glacier-wide mass balance on sub-annual time scales. Relative adjustment of the DEMs is performed with and without a pre-existing lidar DEM as source of ground control points (GCPs), and resulting statistics in snow-free and ice-free areas reveal similar vertical accuracy

scholarly journals AUTOMATIC KAPPA ANGLE ESTIMATION FOR AIR PHOTOS BASED ON PHASE ONLY CORRELATION

2016 ◽  
Vol XLI-B3 ◽  
pp. 131-135
Author(s):  
Z. Xiong ◽  
D. Stanley ◽  
Y. Xin
Keyword(s):  
Bundle Adjustment ◽  
Ground Control ◽  
Correlation Technique ◽  
Control Points ◽  
Initial Value ◽  
Ground Control Points ◽  
Attitude Angle ◽  
Camera Position ◽  
Air Photo ◽  
Orientation Parameters

The approximate value of exterior orientation parameters is needed for air photo bundle adjustment. Usually the air borne GPS/IMU can provide the initial value for the camera position and attitude angle. However, in some cases, the camera’s attitude angle is not available due to lack of IMU or other reasons. In this case, the kappa angle needs to be estimated for each photo before bundle adjustment. The kappa angle can be obtained from the Ground Control Points (GCPs) in the photo. Unfortunately it is not the case that enough GCPs are always available. In order to overcome this problem, an algorithm is developed to automatically estimate the kappa angle for air photos based on phase only correlation technique. This function has been embedded in PCI software. Extensive experiments show that this algorithm is fast, reliable, and stable.

scholarly journals RESULTS OF RESEARCHES ON PHOTOGRAMMETRIC CALIBRATION OF THE SONY CYBER-SHOT DSC-RX1RM2 CAMERA

2019 ◽  
Vol XLII-2/W18 ◽  
pp. 73-77
Author(s):  
S. A. Kadnichansky ◽  
M. B. Kurkov ◽  
V. M. Kurkov ◽  
A. G. Chibunichev ◽  
L. K. Trubina
Keyword(s):  
Aerial Survey ◽  
Ground Control ◽  
Test Field ◽  
Control Points ◽  
Aerial Photos ◽  
Ground Control Points ◽  
Operational Test ◽  
Time Accuracy ◽  
Specific Project

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.

scholarly journals Determining the Optimal Number of Ground Control Points for Varying Study Sites through Accuracy Evaluation of Unmanned Aerial System-Based 3D Point Clouds and Digital Surface Models

Drones ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. 49 ◽  
Author(s):  
Jae Jin Yu ◽  
Dong Woo Kim ◽  
Eun Jung Lee ◽  
Seung Woo Son
Keyword(s):  
Image Processing ◽  
Point Clouds ◽  
Optimal Number ◽  
Ground Control ◽  
Control Points ◽  
Widespread Application ◽  
Ground Control Points ◽  
3D Point Clouds ◽  
Surface Models ◽  
Study Sites

The rapid development of drone technologies, such as unmanned aerial systems (UASs) and unmanned aerial vehicles (UAVs), has led to the widespread application of three-dimensional (3D) point clouds and digital surface models (DSMs). Due to the number of UAS technology applications across many fields, studies on the verification of the accuracy of image processing results have increased. In previous studies, the optimal number of ground control points (GCPs) was determined for a specific area of a study site by increasing or decreasing the amount of GCPs. However, these studies were mainly conducted in a single study site, and the results were not compared with those from various study sites. In this study, to determine the optimal number of GCPs for modeling multiple areas, the accuracy of 3D point clouds and DSMs were analyzed in three study sites with different areas according to the number of GCPs. The results showed that the optimal number of GCPs was 12 for small and medium sites (7 and 39 ha) and 18 for the large sites (342 ha) based on the overall accuracy. If these results are used for UAV image processing in the future, accurate modeling will be possible with minimal effort in GCPs.

scholarly journals The role of national and international geospatial data sources in the management of natural disasters

2014 ◽  
Vol XL-8 ◽  
pp. 47-51 ◽  
Author(s):  
A. Kayi ◽  
M. Erdogan ◽  
A. Yilmaz
Keyword(s):  
Natural Disasters ◽  
Armed Forces ◽  
Geospatial Data ◽  
City Centre ◽  
Control Points ◽  
Van Earthquake ◽  
Ground Sample ◽  
Aerial Photos ◽  
Ground Control Points

An earthquake occurred at Van City on 23 October 2011 at 13:41 local time. The magnitude, moment magnitude and depth of earthquake were respectively MI:6.7, Mw:7.0 and 19.07 km. Van city centre and its surrounding villages were affected from this destructive earthquake. Many buildings were ruined and approximately 600 people died. Acquisition and use of geospatial data is very important and crucial for the management of such kind of natural disasters. In this paper, the role of national and international geospatial data in the management of Van earthquake is investigated.. With an international collaboration with Charter, pre and post-earthquake satellite images were acquired in 24 hours following the Earthquake. Also General Command of Mapping (GCM), the national mapping agency of Turkey, produced the high resolution multispectral orthophotos of the region. Charter presented the orthophotos through 26&ndash;28 October 2012. Just after the earthquake with a quick reaction, GCM made the flight planning of the 1296 km<sup>2</sup> disaster area to acquire aerial photos. The aerial photos were acquired on 24 October 2012 (one day after the earthquake) by UltraCamX large format digital aerial camera. 152 images were taken with 30 cm ground sample distance (GSD) by %30 sidelap and %60 overlap. In the evening of same flight day, orthophotos were produced without ground control points by direct georeferencing and GCM supplied the orthophotos to the disaster management authorities. Also 45 cm GSD archive orthophotos, acquired in 2010, were used as a reference in order to find out the effects of the disaster. The subjects written here do not represent the ideas of Turkish Armed Forces.

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
Keyword(s):  
Large Scale ◽  
Soil Layer ◽  
Aerial Survey ◽  
Control Points ◽  
Aerial Photos ◽  
Emergency Situations ◽  
Ground Control Points ◽  
First Case ◽  
Aerial Vehicle ◽  
Mosaic Generation

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.

scholarly journals PRODUCT ACCURACY EFFECT OF OBLIQUE AND VERTICAL NON-METRIC DIGITAL CAMERA UTILIZATION IN UAV-PHOTOGRAMMETRY TO DETERMINE FAULT PLANE

2016 ◽  
Vol III-6 ◽  
pp. 41-48 ◽  
Author(s):  
C. Amrullah ◽  
D. Suwardhi ◽  
I. Meilano
Keyword(s):  
Fault Plane ◽  
Control Point ◽  
Digital Camera ◽  
Aerial Photographs ◽  
Ground Control ◽  
Control Points ◽  
Point Configuration ◽  
Ground Control Points ◽  
Significant Difference ◽  
Precision And Accuracy

This study aims to see the effect of non-metric oblique and vertical camera combination along with the configuration of the ground control points to improve the precision and accuracy in UAV-Photogrammetry project. The field observation method is used for data acquisition with aerial photographs and ground control points. All data are processed by digital photogrammetric process with some scenarios in camera combination and ground control point configuration. The model indicates that the value of precision and accuracy increases with the combination of oblique and vertical camera at all control point configuration. The best products of the UAV-Photogrammetry model are produced in the form of Digital Elevation Model (DEM) compared to the LiDAR DEM. Furthermore, DEM from UAV-Photogrammetry and LiDAR are used to define the fault plane by using cross-section on the model and interpretation to determine the point at the extreme height of terrain changes. The result of the defined fault planes indicate that two models do not show any significant difference.

scholarly journals Structure-from-Motion on shallow reefs and beaches: potential and limitations of consumer-grade drones to reconstruct topography and bathymetry

Coral Reefs ◽  
2021 ◽  
Author(s):  
C. Gabriel David ◽  
Nina Kohl ◽  
Elisa Casella ◽  
Alessio Rovere ◽  
Pablo Ballesteros ◽  
...  
Keyword(s):  
Shallow Water ◽  
Structure From Motion ◽  
Water Levels ◽  
Aerial Photographs ◽  
Ground Control ◽  
Control Points ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Nonlinear Distortions ◽  
Elevation Model

AbstractReconstructing the topography of shallow underwater environments using Structure-from-Motion—Multi View Stereo (SfM-MVS) techniques applied to aerial imagery from Unmanned Aerial Vehicles (UAVs) is challenging, as it involves nonlinear distortions caused by water refraction. This study presents an experiment with aerial photographs collected with a consumer-grade UAV on the shallow-water reef of Fuvahmulah, the Maldives. Under conditions of rising tide, we surveyed the same portion of the reef in ten successive flights. For each flight, we used SfM-MVS to reconstruct the Digital Elevation Model (DEM) of the reef and used the flight at low tide (where the reef is almost entirely dry) to compare the performance of DEM reconstruction under increasing water levels. Our results show that differences with the reference DEM increase with increasing depth, but are substantially larger if no underwater ground control points are taken into account in the processing. Correcting our imagery with algorithms that account for refraction did not improve the overall accuracy of reconstruction. We conclude that reconstructing shallow-water reefs (less than 1 m depth) with consumer-grade UAVs and SfM-MVS is possible, but its precision is limited and strongly correlated with water depth. In our case, the best results are achieved when ground control points were placed underwater and no refraction correction is used.

scholarly journals Automatic Georeferencing of a Heritage of old analog aerial Photographs

2014 ◽  
Vol II-3 ◽  
pp. 33-40 ◽  
Author(s):  
I. Cléri ◽  
M. Pierrot-Deseilligny ◽  
B. Vallet
Keyword(s):  
Feature Matching ◽  
Aerial Photographs ◽  
Ground Control ◽  
Sensor Calibration ◽  
Control Points ◽  
Iterative Processing ◽  
Perspective Distortion ◽  
Ground Control Points ◽  
Minimum Number ◽  
Historical Photographs

Historical photographs become widely used in geographical and environmental applications. Their enhancement involves converting them into georeferenced data, such as orthoimages or digital models. However no ground control points are available unlike in current image processing, and many problems such as image noise, landscape modifications, perspective distortion and unknown sensor calibration prevent automatic tie-point retrieval with current orthoimages. That is why photograph georeferencing remains a manual and time-consuming task. A novel method is presented in this paper to register photographs with current topographic database using line feature matching. Indeed, geometrical considerations only let avoid high radiometric difference issues when dealing with current orthoimages. Besides topographic database use lets selecting stable through time features, such as road network and historical buildings. A multi-scale approach allows very coarse georeferencing initialization, which can be set manually by a minimum number of ground control points per image set. At each scale an iterative processing improves the line matching and the registration model estimation at the same time. Finally, building integration makes registration more reliable for off-ground objects. Results are promising as georeferencing is much improved and its estimation converges in all test cases.

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