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Titolo:
Evaluation of digital and film hemispherical photography and spherical densiometry for measuring forest light environments
Autore:
Englund, SR; OBrien, JJ; Clark, DB;
Indirizzi:
Selva Biol Stn, San Pedro, Costa Rica Selva Biol Stn San Pedro Costa Rica lva Biol Stn, San Pedro, Costa Rica Florida Int Univ, Dept Biol Sci, Miami, FL 33199 USA Florida Int Univ Miami FL USA 33199 v, Dept Biol Sci, Miami, FL 33199 USA Univ Missouri, Dept Biol, St Louis, MO 63121 USA Univ Missouri St Louis MO USA 63121 ri, Dept Biol, St Louis, MO 63121 USA
Titolo Testata:
CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
fascicolo: 12, volume: 30, anno: 2000,
pagine: 1999 - 2005
SICI:
0045-5067(200012)30:12<1999:EODAFH>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
RADIATION; COVER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
14
Recensione:
Indirizzi per estratti:
Indirizzo: Clark, DB OTS, Interlink 341,POB 02-5635, Miami, FL 33102 USA OTS Interlink 341,POB 02-5635 Miami FL USA 33102 i, FL 33102 USA
Citazione:
S.R. Englund et al., "Evaluation of digital and film hemispherical photography and spherical densiometry for measuring forest light environments", CAN J FORES, 30(12), 2000, pp. 1999-2005

Abstract

This study presents the results of a comparison of digital and film hemispherical photography as means of characterizing forest light environments and canopy openness. We also compared hemispherical photography to spherical densiometry. Our results showed that differences in digital image quality due to the loss of resolution that occurred when images were processed for computer analysis did not affect estimates of unweighted openness. Weighted openness and total site factor estimates were significantly higher in digital images compared with film photos. The differences between the two techniques might be a result of underexposure of the film images or differences in lens optical quality and field of view. We found densiometer measurementssignificantly increased in consistency with user practice and were correlated with total site factor and weighted-openness estimates derived from hemispherical photography. Digital photography was effective and more convenient and inexpensive than film cameras, but until the differences we observedare better explained, we recommend caution when comparisons are made between the two techniques. We also concluded that spherical densiometers effectively characterize forest light environments.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 16/01/21 alle ore 06:00:44