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

Damen, M. C. J.

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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:: The use of multispectral photography in agricultural research. J. G. P. W. Clevers

Document type:: Multivolume work

Structure type:: Chapter

227 Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 .eaf layers modelling: 1 studies. The use of multispectral photography in agricultural research J.G.P.W.Clevers Dept, of Landsurveying and Remote Sensing, Wageningen Agricultural University, Netherlands ABSTRACT: For monitoring crop growth and development, remote sensing techniques have proved to offer great possibilities. Narrow spectral bands in the visible and near-infrared can be very suitable for application in agricultural research (in this paper attention was focussed on application in agricultural field trials). However, to date a low temporal resolution due to high costs for repetitive recordings by a well-calibrated data-acquisition system has been a bottleneck for this monitoring. By using an airborne multispectral photo graphic (MSP) system, recordings of high spectral resolution were obtained through a judicious choice of films and filters (25 - 100 nm bandwidth). By using equipment which was easily available and by selecting an appro priate densitometer, recordings were obtained with a high temporal (fortnightly) and sufficient spatial re solution (in the order of 1 m 2 ). Calibrated reflectance factors of crops were obtained by applying a procedure for atmospheric correction and radiometric calibration using reference targets in the field. The system was tested in field trials at the experimental farm of the Wageningen Agricultural University. The main result was that quantitative information about crops was obtained with larger precision by MSP than by conventional field sampling methods. In this way spectral reflectance characteristics of cereals were ob tained during the growing season in a green, red and infrared band for several treatments (e.g. nitrogen nu trition, sowing date). When comparing results of successive growing seasons, results turned out to be consis tent. 1 INTRODUCTION During the past decades knowledge about remote sen sing techniques and their application to areas such as agriculture has improved considerably. Bunnik (1978) described the possibilities of applying op tical remote sensing in agriculture, particularly with regard to its relation with crop characteris tics such as soil cover, leaf area index (LAI) and dry matter weight. If reflectance factors are re quired with high spectral, spatial and temporal re solution for crop monitoring, Clevers (1986a, 1986b) selected black and white multispectral aerial photo graphy . Systems of aerial photography provide recordings of the reflected visible and infrared radiation. The spectral resolution may be high when adequate films and filters are used in order to achieve a multispectral photographic (MSP) system with nar row bands. The spatial resolution will primarily depend on lens type, altitude, film material and image motion. By using an appropriate microdensito meter or densitometer, with small aperture, quanti tative measurements with high spatial resolution may be obtained. Moreover, the measurements on the photograph can be carried out at exactly determin able locations of an object. The camera equipment can be installed in small planes if small non metric cameras are used (e.g. 70-mm aerial photo graphy). Consequently, cost stays within acceptable limits and a high temporal resolution can be ob tained. All these considerations render black and white multispectral aerial photography the most promising remote sensing technique for application to small areas. The only limitation is that calibration and use of the sensor system must be accurate if this technique is to supply quantitative information, and this has often been a bottle-neck for its applica tion, in particular because of the analog data regis tration (e.g. Curran, 1980, 1982, 1983; Graham, 1980; Kannegieter, 1980; Ross, 1973; Sievers, 1976). Ways in which the photographic recordings have to be cali brated are described by Clevers (1986a, 1986b). In particular the calibration concerns the character istic curve, light fall-off, exposure time, rela tive aperture, transmittance of the optical system and atmospheric correction. This calibration is schematically illustrated in figure 1. MATERIAL AND MEASURED ADDITIONAL INSTRUMENT VARIABLE OPERATION Figure 1: Flow diagram, illustrating the calibra tion of aerial photography. One specific application of remote sensing is in agricultural field trials, in which it is necessary to carry out observations regularly during the gro wing season. Conventionally, the agronomist has two possible approaches at his disposal. The first one is a subjective judgement of plots and estimation of plant characteristics, yielding primarily qualitative information. The second one is based on taking sam ples of a few plants from each plot. This yields quantitative information, because plant characteris tics such as LAI or dry matter weight can be mea

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