Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

Bibliographic data

Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

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

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 3 Spectral signatures of objects. Chairman: G. Guyot, Liaison: N. J. J. Bunnik

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Spectral signatures of soils and terrain conditions using lasers and spectrometers. H. Schreier

Document type:: Multivolume work

Structure type:: Chapter

311 Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 Spectral signatures of soils and terrain conditions using lasers and spectrometers H.Schreier Department of Soil Science, University of British Columbia, Vancouver, B.C., Canada ABSTRACT: A pulsed infrared laser system was flown over a number of test sites and the results showed that high resolution data on terrain and vegetation height, and surface reflection can be obtained simultaneously. With this combined data set it is possible to examine the effect of surface roughness on spectral reflection measurements and this greatly facilitates terrain and vegetation assessments. To explore the development of multispectral lasers ground based reflection measurements were made with a spectrometer using three different sets of soil samples. The results showed that % carbon, % iron and % sand content were significantly correlated with spectral reflection measurements at 550, 630 and 1600 nm wavelengths respectively. However, these relationships are not universal and are only applicable on a site specific basis. Organic carbon could only be predicted with confidence from soils originating from a field where the organic carbon content was highly variable and greater than 2.0%. In a different sample set where organic carbon content was below 2% the % sand variability could be predicted. Finally, a third set of samples, originating from mine tailings having no carbon present and high iron variability, showed significant relationships with reflection at 630 nm wavelength. These results suggest that if we are interested in quantifying soil fertility conditions the development and use of a multispectral laser might provide a new dimension to remote sensing since it would provide both essential reflection and surface roughness assessments at the same time. 1 INTRODUCTION 2 REMOTE SENSING WITH AN AIRBORNE LASER Surface roughness has a significant influence on de tailed spectral reflection measurements and until recently this subject has been largely ignored because of the difficulties in measuring roughness by remote means. With the introduction of airborne lasers it is now possible to not only measure the terrain surface reflection but also to quantify surface roughness or height variations. As shown by Schreier et al (1984), Krabill et al (1984) and Schreier et al (1985) terrain height variation can be determined with a pulsed airborne laser reaching vertical accuracies of better than 20 cm and a newer model laser as indicated by Jepsky (1986) has shown even greater accuracy. In this way tree height measurements and tracings of the canopy of individual trees is readily possible. The laser generates an active energy source and laser amplitude or reflec tion measurements can be carried out simultaneously with the height measurements and this provides a new dimension in detailed terrain assessments by remote sensing. The surface roughness or height component is of particular interest in vegetation studies which involve biomass determinations, species identifica tions, nutrient deficiency assessment through foliage analysis, and assessment of toxicity or plant stress for geochemical prospecting. Another application where the assessment of roughness is of importance is in the analysis of soil fertility where the surface structure and cultivation pattern at the soil surface has a profound influence on reflection. Current lasers operate at single narrow wavelength bands and in order to fully exploit this technology multispectral laser capabilities need to be explored. It is the aim of this paper to first document the results of airborne laser test flights so as to emphasize the laser capabilities at a single wave length band. The second aim is to provide background information for spectral properties which are essen tial for the development, application and use of multispectral airborne lasers. Examples from the airborne laser test flights focus on vegetation applications, while the quantification of soil types for fertilizer assessments is emphasized in the second aim. 2.1 Description of laser system A gallium arsenide laser built by Associated Controls and Communication Inc. (ACCI) was used in this study The system operates at 904 nm wavelength, has a pulse rate of 2000 pps and a peak power output of 80 watts. In order to provide optimum ground coverage and to facilitate data verification an inertial navigation system, a photogrammetric camera, and an airborne data acquisition system were inter linked with the laser. The footprint of the laser covered an area of 50 x 50 cm on the ground. 2.2 Terrain assessment with the airborne laser The system was tested for height and reflection accuracy over the National Research Council photo grammetric test site in Sudbury and the research forest at the Petawawa National Forestry Institute. As reported elsewhere (Schreier et al 1984) average height accuracies between 10 and 24 cm were obtained by the airborne laser. A wide range of vegetation could be differentiated on the basis of reflection measurements alone and this in spite of the limita tion of using a single wavelength frequency. An example of the dual capability of height and reflection measurement is provided in Figure 1 which shows a height and reflection profile of a mixed forest transect at the Petawawa research station. As indicated in Figure 1 grass, broadleaf, and coniferous trees could be separated by reflection measurements alone but the height profile clearly facilitates the interpretations since some broadleaf trees reflect the near infrared energy at a rate similar to some of the understory vegetation. An additional component which helps in the interpreta tion is the fact that the laser penetrates the coni fer tree canopy much more frequently than the broad leaf tree canopy. This gives a more spiky tree profile for spruce and pine trees and a more rounded profile for maple and poplar trees which in fact reflects the tree structure. Using a very high pulse

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