Using Direct Linear Transformation (Dlt) Method for Aerial Photogrammetry Applications

El-Ashmawy, Khalid L. A.

doi:10.3846/gac.2018.1629

Cited by 18 publications

(13 citation statements)

References 2 publications

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“…The DLT (direct linear transformation) algorithm was employed in order to obtain spatial data by applying a system of four CMOS matrices [ 24 , 25 ]. The X, Y, Z coordinates with which the trajectory of the marker attached to the analyzed mechanical object can be obtained, are related to the calculation of the U and V coordinates of the optical sensor.…”

Section: Methodsmentioning

confidence: 99%

Specifying Inputs for the Computational Structure of a Surgical System via Optical Method and DLT Algorithm Based on In Vitro Experiments on Cardiovascular Tissue in Minimally Invasive and Robotic Surgery

Ilewicz

Ładyżyńska-Kozdraś

2022

Sensors

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With the application of four optical CMOS sensors, it was possible to capture the trajectory of an endoscopic tool during an in vitro surgical experiment on a cardiovascular preparation. This was due to the possibility of obtaining a path when a reflective marker was attached. In the work, APAS (Ariel Performance Analysis System) software and DLT (direct linear transformation) algorithm were used. This made it possible to acquire kinematic inputs to the computational model of dynamics, which enabled, regardless of the type of surgical robot structure, derivation of the analogous motion of an endoscopic effector due to the mathematical transformation of the trajectory to joints coordinates. Experiments were carried out with the participation of a practiced cardiac surgeon employing classic endoscopic instruments and robot surgical systems. The results indicated by the experiment showed that the inverse task of kinematics of position for the surgical robot with RCM (remote center of motion) structure was solved. The achieved results from the experiment were used as inputs for deriving a numerical dynamics model of surgical robot during transient states that was obtained by applying the finite element method and by driving dynamics moments acquired through the block diagrams method using a steering system with DC (direct current) motor and PID (proportional–integral–derivative) controller. The results section illustrates the course of kinematic values of endoscopic tools which were employed to apply numerical models as inputs, the course of the driving torque of the model of the surgical robot that enabled the selection of the drive system and the strength values, stresses and displacements according to von Mises hypothesis in its structure during the analysis of transient states that made it possible to establish the strength safety of the surgical robot. For the conducted experiments, the accuracy was ± 2 [mm]. In the paper, the employment of optical CMOS sensors in surgical robotics and endoscopy is discussed. The paper concludes that the usage of optical sensors for determining inputs for numerical models of dynamics of surgical robots provides the basis for setting the course of physical quantities that appear in their real object structure, in manners close to reality.

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Section: Methodsmentioning

confidence: 99%

Specifying Inputs for the Computational Structure of a Surgical System via Optical Method and DLT Algorithm Based on In Vitro Experiments on Cardiovascular Tissue in Minimally Invasive and Robotic Surgery

Ilewicz

Ładyżyńska-Kozdraś

2022

Sensors

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“…The camera calibration procedures follow the steps below: Calculate the related camera projection matrix using Direct Linear Transformation (DLT), defined as follows [25][26][27][28][29]:…”

Section: Camera Calibrationmentioning

confidence: 99%

Unstable Landing Platform Pose Estimation Based on Camera and Range Sensor Homogeneous Fusion (CRHF)

Sefidgar

Landry

2022

Drones

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Much research has been accomplished in the area of drone landing and specifically pose estimation. While some of these works focus on sensor fusion using GPS, or GNSS, we propose a method that uses sensors, including four Time of Flight (ToF) range sensors and a monocular camera. However, when the descending platform is unstable, for example, on ships in the ocean, the uncertainty will grow, and the tracking will fail easily. We designed an algorithm that includes four ToF sensors for calibration and one for pose estimation. The landing process was divided into two main parts, the rendezvous and the final landing. Two important assumptions were made for these two phases. During the rendezvous, the landing platform movement can be ignored, while during the landing phase, the drone is assumed to be stable and waiting for the best time to land. The current research modifies the landing part as a stable drone and an unstable landing platform, which is a Stewart platform, with a mounted AprilTag. A novel algorithm for calibration was used based on color thresholding, a convex hull, and centroid extraction. Next, using the homogeneous coordinate equations of the sensors’ touching points, the focal length in the X and Y directions can be calculated. In addition, knowing the plane equation allows the Z coordinates of the landmark points to be projected. The homogeneous coordinate equation was then used to obtain the landmark’s X and Y Cartesian coordinates. Finally, 3D rigid body transformation is engaged to project the landing platform transformation in the camera frame. The test bench used Software-in-the-Loop (SIL) to confirm the practicality of the method. The results of this work are promising for unstable landing platform pose estimation and offer a significant improvement over the single-camera pose estimation AprilTag detection algorithms (ATDA).

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“…PhotoMap is under continuous development and new capabilities are developed and added to widen its applications. PhotoMap contains 7 modules namely BUNDLE [2], Self-Calibration [9], DLT [13],…”

Section: Wwwetasrcommentioning

confidence: 99%

Simulated Photogrammetric Data for Testing the Performance of Photogrammetric Instruments and Systems

El-Ashmawy¹

2022

Eng. Technol. Appl. Sci. Res.

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The generation of mathematical photograms (photos) as data is universally accepted as the basis for photogrammetric studies. New development in the field of computer technology has had a major influence on photogrammetry. This paper aims to describe the development of a computer system called SimuPhotos designed to produce simulated data in different forms for testing photogrammetric methodologies, software, and instruments. SimuPhotos is capable of generating photogrammetric blocks with different specifications. It generates the simulated data for the whole block, strips, or selected photos. The simulated free error data include the camera interior orientation parameters, ground coordinates of points, and for each photograph, camera exterior orientation parameters, and the photo coordinates of imaged points. To increase the capabilities of the developed system, it has a special error generator to get normally distributed error(s) with arbitrary mean(s) and standard deviation(s). The obtained errors are then, if required, applied to the error-free photo and ground coordinates of points. The developed system interfaces CAD technology to generate simulated photogrammetric data in DXF and raster formats which are suitable for testing the photogrammetric instruments and softcopy systems. SimuPhotos has been used for testing the analytical photogrammetric system PhotoMap. The results showed that PhotoMap is free of system error and is functional. Also, the results showed that SimuPhotos can effectively provide a convenient, economical, and accurate testing tool for photogrammetric systems. The developed system is quite versatile and affordable.

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Using Direct Linear Transformation (Dlt) Method for Aerial Photogrammetry Applications

Cited by 18 publications

References 2 publications

Specifying Inputs for the Computational Structure of a Surgical System via Optical Method and DLT Algorithm Based on In Vitro Experiments on Cardiovascular Tissue in Minimally Invasive and Robotic Surgery

Specifying Inputs for the Computational Structure of a Surgical System via Optical Method and DLT Algorithm Based on In Vitro Experiments on Cardiovascular Tissue in Minimally Invasive and Robotic Surgery

Unstable Landing Platform Pose Estimation Based on Camera and Range Sensor Homogeneous Fusion (CRHF)

Simulated Photogrammetric Data for Testing the Performance of Photogrammetric Instruments and Systems

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