Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

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

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

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:: [TP-2 SPECTRAL SIGNATURES]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: The change of spectral signatures of beech and spruce by forest damage. W. Kirchhof & H. Hoffmann

Document type:: Multivolume work

Structure type:: Chapter

Bidirectional Reflectance Measurements instrument : spectral range: spectral resolution: viewing angle: illumination angle: sample measurement: reference measurement: IFOV : laboratory illumination source: Iris Mark IV Spectroradiometer double beam design for two targets: sample, reference 0.49 - 2.50 pm, 2nm at 0.49 - 1.06 pm 2xSi 4nm at 1.04 - 1.88 pm 2xPbS 6nm at 1.84 - 2.50 pm cooled 243 K 0° 30° Laboratory measurement 3-5 continuous scans white standard, Halon G-80 parallel to each sample scan, before and after sample change on the sample beam 12 x 4 cm 2 at 140 cm distance quartz-halogene 1000 W 180 cm above sample Table 3 Measurement configuration and instrument data for the simulation of multispectral scanner data acquisition, nadir looking at noon The measurement configuration and the instrument for the simulation of multispectral scanner data acquisition, nadir looking at noon, is described in table 3. The high resolution spectral measurements were done in one continous scan. The spectra of the vegetation sample and the reference (white standard) were acquired simultaneously, such that variation in illumination intensity and spectrum can be corrected for automatically. The signal level was monitored for gain and scan time selection. The two channels of data are both stored and recorded for later processing as two separate spectra calibrated for radiance, or as a single ratio spectrum calibrated in terms of percent reflectance. 4 . Measurement results Reflectance of single and up to seven stacked branches of beech (fagus silvatica) and spruce (picea abies) was measured from 0.49 - 2.50 pm wavelength with the IRIS Mark IV spectroradiometer. Each sample was measured several times, 5 times in 1988 and 3 times in 1989. For each measurement the branches were rearranged. For evaluation the mean values are presented. The background had an uniform reflectance of smaller than ten percent. In 1988 the measurements focused on the spectral signature of beech, for comparison spruce branches were measured in parallel. In 1989 the main objectiv was the measurement of the spectral signature of branches from damaged beech and spruce trees. When healthy beech branches were stacked, the most obvious change in reflection occurs in the infrared region (IR). Reflection increases with every additional branch and reaches the maximum with 5-7 branches, see figure 1. Reflection is relatively unchanched in the visible (vis) and the water absorption region at 1900 nm. This is consistent with the interpretation, that pigments of the first surface layer determine the spectral response in this wavelength region. In the infrared reflection is influenced by the contribution of multiple transmitted and scattered radiation and water and/or carbon dioxide absorption. For the measuring configuration, as described before, optical thickness was reached for 5-7 stacked branches. Figure 2 displays the reflectance of five stacked branches of beech with sun leaves (1), with shadow leaves (2), with discoloured leaves (yellowing) (3) and spruce (4). Differences in species and colour determine the course, mainly the level of the near infrared plateau, besides smaller variations in reflectance of sun leaves and shadow leaves of beech. The curves follow the general shape of spectral signature of green vegetation. In the visible the course of discoloured beech branches differs considerably from those of green beech. Yellowing produces a raise of reflectance in the green - red region, a red shift of the reflection peak of « 10 nm and a change of its course at the red edge, which can be attributed to a narrowing of the chlorophyll absorption near 680 nm. Figure 3 shows these effects clearly. Most prominent is the double peaked feature in the division spectrum of the yellowed beech sample. The first maximum is caused by the increase and red shift of the reflectance peak. The second maximum is situated in the red edge. It is caused by the earlier 52

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