XXII ISPRS Congress 2012: Technical Commission VII

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Multivolume work

Persistent identifier:: 1663813779

Title:: XXII ISPRS Congress 2012

Sub title:: Melbourne, Australia, 25 August-1 September 2012

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663813779

Language:: English

Additional Notes:: Kongress-Thema: Imaging a sustainable future

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1663821976

Title:: Technical Commission VII

Scope:: 546 Seiten

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663821976

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(39,B7)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist ermittelt.; Literaturangaben

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [VII/7, III/2, V/3: WAVEFORM LIDAR FOR REMOTE SENSING]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: LIDAR WAVEFORM SIMULATION OVER COMPLEX TARGETS Seongjoon Kim, Impyeong Lee, Mijin Lee

Document type:: Multivolume work

Structure type:: Chapter

International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia LIDAR WAVEFORM SIMULATION OVER COMPLEX TARGETS Seongjoon Kim”, Impyeong Lee * *, Mijin Lee * * Dept. of Geoinfomatics, The University of Seoul, 90 Jeonnong-dong Dongdaemun-gu Seoul, Korea - (sinus7953, iplee, mj-lee)@uos.ac.kr Commission III, WG III/2 KEY WORDS: Simulation, LIDAR, Waveform, sub-beam, geometry, radiometry, Model ABSTRACT: Unlike discrete-return LIDAR system that measures the return times of some echoes, waveform LIDAR provides the full-waveform data by digitising multi-echoes. From the waveform data we can extract more information about the geometry and reflectance of the target surfaces by applying various algorithms to interpret waveform. There have been many researches about the laser beam's interaction with the illuminated surfaces and the diverse algorithms for waveform processing. The purpose of this paper is to suggest the method to simulate waveform coming from complex targets. First, we analysed the previous relevant works. And based on these we attempted to generate the simulated waveform over the complex surfaces. For the waveform simulation, we defined the sub- beams spread with a consistent interval within the beam's divergence coverage. Each sub-beam has its geometry (origin and direction) and the transmitted energy considering the laser beam's profile. Then, we searched the surfaces that intersect with sub- beams using ray-tracing algorithm, and computed the intersection points and the received energies. Using on the computed distance, the received energy and predefined pulse model, we generated the signals of echoes and put them together into a waveform. Finally, we completed the waveform simulation adding the signal noise. As a result of performing waveform simulation, we confirmed that the waveform data was successfully simulated by the proposed method. We believe that our method of the waveform simulation will be helpful to understand the waveform data and develop the algorithms for the waveform processing. 1. INTRODUCTION But it takes long time and a tremendous amount cost to acquire by real systems. A laser scanning system is capable of acquire the 3D point In this paper, we suggest the method to simulate realistic and cloud by sampling the surface of objects. In civilian precise waveforms by sensor modelling of full-waveform lidar applications, airborne laser scanning systems are widely used systems in geometric and radiometric aspects. for various applications such as bare ground modelling, target In order to simulate waveforms of complex surfaces, we detection, object reconstruction, forest biomass estimation, adopted sub-beam processing which are defined around the corridor mapping and change detection. Besides, because a laser laser beam ray within beam divergence angle. Assuming an beam is robust against the obscuration (e.g. smoke and flare) ^ echo is originated from the individual reflected sub-beam, each rather than electro optic systems, these systems are also ^ sub-beam is separately processed. First, we computed the employed for surveillance and reconnaissance to detect targets intersection points between sub-beams and target surfaces in in military applications, owing to the robustness. geometry. In the geometric process, we can obtain the ranges of In topographic mapping, lidar systems used typically have a sub-beam ray from the origin of the sensor to the target surfaces. single detector and scanning mirror to enlarge the coverage. In radiometric simulation, the return energy of each sub-beam They shot a laser pulse with Gaussian shape and measure its with the transmitted energy which is assigned by beam profile is TOF (time of flight) by pulse detection. When transmitted laser calculated using laser equation. And then, for each sub-beam, pulses encounter with target, there may be lots of scatterings by the return echo is generated using pulse model with the return many surfaces within the footprint and they contribute the time and energy. Finally, waveform is simulated by summing waveform, even if the beam divergence (0.2~2 m) is very small the individual echoes of sub- beams and noise. (Mallet et al, 2009). The traditional discrete return systems (or multiple pulse laser scanning systems) output the travel times of individual echoes up to six returns (Mallet ez al, 2009). On the 2. SIMULATION METHOD other hands, recently advanced systems, called full-waveform lidar system, have the capability to record the waveform signals, 2.1 Overview as it is, by digitizing with high frequency. These waveforms can provide additional information about the structures and the In general, the pulsed lidar system measures ranges by the flight physical properties of the surfaces. For example, there are time of the laser pulse. Then 3D points are computed by increasingly many early works to analyse vertical structure for georeferencing with the data from GPS, IMU and scanning forest biomass or detect concealed targets by interpreting system. Figure 1 illustrates how the system obtains full- waveforms. waveform data from a single laser shot. First, a transmitted laser To develop and validate the algorithms of processing pulse may encounter with many target surfaces on the footprint waveforms, there needs many waveform data of various targets. not on a point due to beam divergence. And then, the * Corresponding author. 517

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