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: THEORY AND EXPERIMENTS IN RADAR AND LIDAR]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: FULL WAVEFORM ACTIVE HYPERSPECTRAL LIDAR T. Hakala, J. Suomalainen, S. Kaasalainen

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 FULL WAVEFORM ACTIVE HYPERSPECTRAL LIDAR T. Hakala**, J. Suomalainen?, S. Kaasalainen* ^ Department of Photogrammetry and Remote Sensing, Finnish Geodetic Institute, Geodeetinrinne 2, Masala, 02431, Finland — (teemu.hakala, juha.suomalainen, sanna.kaasalainen) @ fgi.fi KEY WORDS: Full waveform, Hyperspectral, LiDAR, Supercontinuum, Reflectance, Spectral indices ABSTRACT: We have developed a prototype full waveform hyperspectral LiDAR and investigated its potential for remote sensing applications. Traditionally hyperspectral remote sensing is based on passive measurement of sunlit targets. These methods are sensitive to errors in illumination conditions and lack the range information. Our prototype can measure both the range and the spectral information from a single laser pulse. At this stage, the instrument is optimized for short range terrestrial applications. An active hyperspectral LIDAR opens up new possibilities for LIDAR data analysis. The lack of spectral information in traditional monochrome LiDARSs rules out many of the classification techniques available for processing of hyperspectral data. Similarly, passive hyperspectral data does not allow extensive use of the classifications based on 3D shape parameters. With both hyperspectral and range data available in a single dataset, the best of the techniques can be applied to form more reliable classification results. The data also allows the mapping of spectral indices in 3D. As an example a Norway spruce is measured and spatial distribution of several spectral indices is illustrated. 1. INTRODUCTION Supercontinuum laser sources produce directional broadband laser pulses by making use of cascaded nonlinear optical interactions in a nonlinear optical fiber (see Dudley et al., 2006 for a review). The commercial availability of supercontinuum laser technology has lead into a number of applications in the recent years, such as those in biomedical optics (e.g., Kudlinski et al, 2010). Combined with a hyperspectral time-of-flight sensor, the supercontinuum laser sources can be used for simultaneous measurement of distance and reflectance spectrum, which has been the basis for our recent efforts in development of the hyperspectral LiDAR. Simultaneous topographic and spectral remote sensing has thus far been based on passive imaging spectroscopy, fused with laser scanner point clouds (Jones et al., 2010; Puttonen et al., 2011; Thomas et al, 2009). Simultaneous geometric and spectral information can also be retrieved by the means of a novel approach for photogrammetric point cloud creation from automatic multispectral image matching (Honkavaara et al., 2012). Active hyperspectral imaging applications acquire a spectral signature for every pixel in the image captured by an imaging detector, but they do not produce range information (Johnson et al., 1999; Nischan et al., 2003). Range information is included in multi-wavelength laser scanners that use separate monochromatic lasers as light sources for each wavelength (Pfennigbauer and Ullrich, 2011). For these, the wavelength channels are determined by the light sources. The hyperspectral scanning LiDAR combines active hyperspectral imaging and laser scanning with the same instrument, with no registration problems between data sets. The hyperspectral LiDAR produces a point cloud and hyperspectral reflectance: (xy,zR(A), where R(A) is the backscattered reflectance R as a function of the wavelength A. The information content of the new type of data is vast and creates new prospects for improving automatic data processing and target characterization for laser scanning (LiDAR) data. We present the design of a full waveform hyperspectral LiDAR and its first demonstrations in the remote sensing of vegetation. The concept was first studied with a scanning active hyperspectral measurement system (Suomalainen et al., 2011), where the active hyperspectral intensity data was fused with simultaneous terrestrial laser scanner measurement. This lead to the development of the scanning LiDAR instrument presented in this paper (see also Hakala et al., 2012), and enabled us to study the usage of hyperspectral 3D point clouds in target classification (Puttonen et al., 2010). To our knowledge, this is the first full waveform hyperspectral LiDAR producing spectral 3D point clouds and exploiting the supercontinuum laser technology, and one of the first environmental applications of supercontinuum lasers. 2. FULL WAVEFORM ACTIVE HYPERSPECTRAL LIDAR 2.1 The Instrument We have assembled an optical setup (Fig. 1) for measuring the time-of-flight and return intensity of a hyperspectral laser pulse. The supercontinuum laser (NKT Photonics, SuperK) produces 1 ns pulses at repetition rate of 24 kHz and average power of 100 mW. The broadband output laser is collimated using a refracting collimator (Thorlabs, CFC-5-A). The collimated beam passes through a beam sampler, which takes a part of the beam for triggering the time-of-flight measurement. An off-axis parabolic mirror (50.8 mm diameter, 152.4 mm effective focal length and 90° off-axis angle) is used as the primary collecting optic. The off-axis parabolic mirror is focused to a spectrograph (Specim, ImSpector V10). A 16-element avalanche photo diode (APD) array module (Pacific Silicon Sensor) is used to convert the spectrally separated light to analog voltages. The APD module has built-in transimpedance amplifiers (Analog Devices, AD8015) with a bandwidth of 240 MHz producing an unambiguous resolution of approximately 4 ns. 12-bit analog to

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