Engineering Commons^™

Visualization Of Three-Dimensional Models From Multiple Texel Images Created From Fused Ladar/Digital Imagery, Cody C. Killpack

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The ability to create three-dimensional (3D) images offers a wide variety of solutions to meet ever increasing consumer demands. As popularity for 3D cinema and television continues to grow, 3D images will remain an important area of research and development. While there are a variety of ways to create a 3D model, textel images are quickly become the preferred solution that has been captured with a texel camera. The combination of multiple texel images taken around a scene can be used to form a texel model. Offering both visual and dimensional accuracy, texel models are becoming invaluable tools for disaster …

Three-Dimensional Image Reconstruction Using Bundle Adjustment Applied To Multiple Texel Images, Bikalpa Khatiwada, Scott E. Budge

Electrical and Computer Engineering Faculty Publications

The importance of creating 3D imagery is increasing and has many applications in the eld of disaster response, digital elevation models, object recognition, and cultural heritage. Several methods have been proposed to register texel images, which consist of fused lidar and digital imagery. The previous methods were limited to registering up to two texel images or multiple texel swaths having only one strip of lidar data per swath. One area of focus still remains to register multiple texel images to create a 3D model.

The process of creating true 3D images using multiple texel images is described. The texel camera …

Heterodyne Ladar System Efficiency Enhancement Using Single-Mode Optical Fiber Mixers, Donald K. Jacob, Martin B. Mark, Bradley D. Duncan

Bradley D. Duncan

A theoretical performance analysis of a heterodyne ladar system incorporating a single-mode fiber receiver has been performed. For our purposes, the performance parameters of interest are the coupling and mixing efficiency of the ladar receiver, as they relate to the overall system carrier-to-noise ratio. For a receiver incorporating a single-mode fiber mixer, the received and local-oscillator fields are matched both spatially and temporally at the detector, yielding 100% mixing efficiency. We have therefore focused our efforts on determining an expression for the efficiency with which a diffuse return from a purely speckle target can be coupled into the receiving leg …

Optical-Fiber Preamplifiers For Ladar Detection And Associated Measurements For Improving The Signal-To-Noise Ratio, Michael Salisbury, Paul Mcmanamon, Bradley Duncan

Bradley D. Duncan

In an effort to increase achievable postdetection signal-tonoise ratios (SNRs) of continuous-wave, 1-gm all-solid-state ladar systems, a prototype rare-earth-doped optical-fiber amplifier has been included in the optical return signal path of both a heterodyne and a directdetection ladar system. We provide numerical predictions for SNR increases according to our previously developed theory. We also detail our experimental efforts and provide the results of SNR measurements for four distinct cases: direct ladar detection with and without a fiber amplifier, and heterodyne ladar detection with and without a fiber amplifier. Experimentally measured increases in SNRs for ladar systems incorporating an optical-fiber amplifier …

Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard Masters, Martin Mark, Bradley Duncan

Bradley D. Duncan

The ability of a ladar system to resolve two or more separate returns from a combined echo is related to the effective correlation bandwidth of the pulse emitted by the ladar system. Phase modulation of an outgoing pulse introduces additional frequency components, which increases the effective correlation bandwidth of the pulse and thus improves the range resolution of the system. In this paper, we discuss the general theoretical basis for achieving improved range resolution using a modulated waveform and a matched filter receiver. We then demonstrate these concepts by considering the particular case of improved range resolution for a sinusoidally …

Sensitivity Improvement Of A 1-Μm Ladar System Incorporating An Active Optical Fiber Preamplifier, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan

Bradley D. Duncan

In an effort to increase the SNR of a continuous wave, 1-μm all solid state ladar system, a rare-earth-doped optical fiber amplifier is investigated as a preamplifier for ladar return signals. The experimental system is detailed and a theoretical analysis of the fiber amplifier's effect on both heterodyne and direct detection schemes is provided. Beginning with the optical powers incident on the detector, the signal and noises are analyzed, through the detector electronics, to predict the SNR. The SNR is then plotted as a function of the return signal power, and a SNR threshold is defined to determine a minimum …

A Technique For Removing Platform Vibration Noise From A Pulsed Ladar Vibration Sensor, Troy Sturm, R. Richmond, Bradley Duncan

Bradley D. Duncan

A technique has been developed for removing platform-induced vibration noise from a pulsed ladar vibration sensor. Deriving the vibrational characteristics of the platform is accomplished by simulating ambient atmospheric aerosols as a stationary reference target. Using a pulsed coherent detection ladar, the instantaneous Doppler frequency shifts from both aerosols and a distant hard target are measured and recorded, while the data acquisition is range gated so that both Doppler measurements are made from a single pulse. Periodic measurements are then made to develop a time history of the fluctuations in the Doppler signals, after which two vibration spectra are derived …

Automatic Registration Of Fused Lidar/Digital Imagery (Texel Images) For Three-Dimensional Image Creation, Scott E. Budge, Neeraj S. Badamikar, Xuan Xie

Electrical and Computer Engineering Faculty Publications

Several photogrammetry-based methods have been proposed that the derive three-dimensional (3-D) information from digital images from different perspectives, and lidar-based methods have been proposed that merge lidar point clouds and texture the merged point clouds with digital imagery. Image registration alone has difficulty with smooth regions with low contrast, whereas point cloud merging alone has difficulty with outliers and a lack of proper convergence in the merging process. This paper presents a method to create 3-D images that uses the unique properties of texel images (pixel-fused lidar and digital imagery) to improve the quality and robustness of fused 3-D images. …

Range Resolution Improvement Of Eyesafe Ladar Testbed (Elt) Measurements Using Sparse Signal Deconvolution, Scott E. Budge, Jacob H. Gunther

Civil and Environmental Engineering Faculty Publications

The Eyesafe Ladar Test-bed (ELT) is a experimental ladar system with the capability of digitizing return laser pulse waveforms at 2 GHz. These waveforms can then be exploited o-line in the laboratory to develop signal processing techniques for noise reduction, range resolution improvement, and range discrimination between two surfaces of similar range interrogated by a single laser pulse. This paper presents the results of experiments with new deconvolution algorithms with the hoped for gains of improving the range discrimination of the ladar system. The sparsity of ladar returns is exploited to solve the deconvolution problem in two steps. The rst …

Improved Registration For 3d Image Creation Using Multiple Texel Images And Incorporating Low-Cost Gps/Ins Measurements, Scott E. Budge, Xuan Xie

Civil and Environmental Engineering Faculty Publications

The creation of 3D imagery is an important topic in remote sensing. Several methods have been developed to create 3D images from fused ladar and digital images, known as texel images. These methods have the advantage of using both the 3D ladar information and the 2D digital imagery directly, since texel images are fused during data acquisition. A weakness of these methods is that they are dependent on correlating feature points in the digital images. This can be dicult when image perspectives are signicantly dierent, leading to low correlation values between matching feature points. This paper presents a method to …

Compressive Point Cloud Super Resolution, Cody S. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Automatic target recognition (ATR) is the ability for a computer to discriminate between different objects in a scene. ATR is often performed on point cloud data from a sensor known as a Ladar. Increasing the resolution of this point cloud in order to get a more clear view of the object in a scene would be of significant interest in an ATR application.

A technique to increase the resolution of a scene is known as super resolution. This technique requires many low resolution images that can be combined together. In recent years, however, it has become possible to perform super …

Signal Processing On Digitized Ladar Waveforms For Enhanced Resolution On Surface Edges, Kevin D. Neilsen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Automatic target recognition (ATR) relies on images from various sensors including 3-D imaging ladar. The accuracy of recognizing a target is highly dependent on the number of points on the target. The highest spatial frequencies of a target are located on edges. Therefore, a higher sampling density is desirable at these locations. A ladar receiver captures information on edges by detecting two surfaces when the beam lands partially on one surface and partially on another if the distance between the surfaces is greater than the temporal pulse width of the laser.

In recent years, the ability to digitize the intensity …

A Ladar-Based Pose Estimation Algorithm For Determining Relative Motion Of A Spacecraft For Autonomous Rendezvous And Dock, Ronald Christopher Fenton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Future autonomous space missions will require autonomous rendezvous and docking operations. The servicing spacecraft must be able to determine the relative 6 degree-of-freedom (6 DOF) motion between the vehicle and the target spacecraft. One method to determine the relative 6 DOF position and attitude is with 3D ladar imaging. Ladar sensor systems can capture close-proximity range images of the target spacecraft, producing 3D point cloud data sets. These sequentially collected point-cloud data sets were then registered with one another using a point correspondence-less variant of the Iterative Closest Points (ICP) algorithm to determine the relative 6 DOF displacements. Simulation experiments …

Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard T. Masters, Martin B. Mark, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

The ability of a ladar system to resolve two or more separate returns from a combined echo is related to the effective correlation bandwidth of the pulse emitted by the ladar system. Phase modulation of an outgoing pulse introduces additional frequency components, which increases the effective correlation bandwidth of the pulse and thus improves the range resolution of the system. In this paper, we discuss the general theoretical basis for achieving improved range resolution using a modulated waveform and a matched filter receiver. We then demonstrate these concepts by considering the particular case of improved range resolution for a sinusoidally …

Heterodyne Ladar System Efficiency Enhancement Using Single-Mode Optical Fiber Mixers, Donald K. Jacob, Martin B. Mark, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

A theoretical performance analysis of a heterodyne ladar system incorporating a single-mode fiber receiver has been performed. For our purposes, the performance parameters of interest are the coupling and mixing efficiency of the ladar receiver, as they relate to the overall system carrier-to-noise ratio. For a receiver incorporating a single-mode fiber mixer, the received and local-oscillator fields are matched both spatially and temporally at the detector, yielding 100% mixing efficiency. We have therefore focused our efforts on determining an expression for the efficiency with which a diffuse return from a purely speckle target can be coupled into the receiving leg …

Optical-Fiber Preamplifiers For Ladar Detection And Associated Measurements For Improving The Signal-To-Noise Ratio, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

In an effort to increase achievable postdetection signal-tonoise ratios (SNRs) of continuous-wave, 1-gm all-solid-state ladar systems, a prototype rare-earth-doped optical-fiber amplifier has been included in the optical return signal path of both a heterodyne and a directdetection ladar system. We provide numerical predictions for SNR increases according to our previously developed theory. We also detail our experimental efforts and provide the results of SNR measurements for four distinct cases: direct ladar detection with and without a fiber amplifier, and heterodyne ladar detection with and without a fiber amplifier. Experimentally measured increases in SNRs for ladar systems incorporating an optical-fiber amplifier …

Sensitivity Improvement Of A 1-Μm Ladar System Incorporating An Active Optical Fiber Preamplifier, Michael S. Salisbury, Paul F. Mcmanamon, Bradley D. Duncan

Electro-Optics and Photonics Faculty Publications

In an effort to increase the SNR of a continuous wave, 1-μm all solid state ladar system, a rare-earth-doped optical fiber amplifier is investigated as a preamplifier for ladar return signals. The experimental system is detailed and a theoretical analysis of the fiber amplifier's effect on both heterodyne and direct detection schemes is provided. Beginning with the optical powers incident on the detector, the signal and noises are analyzed, through the detector electronics, to predict the SNR. The SNR is then plotted as a function of the return signal power, and a SNR threshold is defined to determine a minimum …