Using orthoimages generated from oblique terrestrial photography to estimate and monitor vegetation cover

Wallace, L, San Martin Saldias, D, Reinke, K, HILLMAN, S, Hally, B and Jones, S 2019, 'Using orthoimages generated from oblique terrestrial photography to estimate and monitor vegetation cover', Ecological Indicators, vol. 101, pp. 91-101.


Document type: Journal Article
Collection: Journal Articles

Title Using orthoimages generated from oblique terrestrial photography to estimate and monitor vegetation cover
Author(s) Wallace, L
San Martin Saldias, D
Reinke, K
HILLMAN, S
Hally, B
Jones, S
Year 2019
Journal name Ecological Indicators
Volume number 101
Start page 91
End page 101
Total pages 11
Publisher Elsevier BV
Abstract Percent vegetation cover is important variable used in understanding ecosystem processes, vegetation health and productivity. Downward looking images captured using a handheld camera have been demonstrated as a viable option for rapidly capturing in situ information to assess vegetation cover. This technique, however, is prone to perspective distortions biasing cover estimates towards taller vegetation elements. In this paper we present a new approach to generate imagery for use in vegetation cover estimation utilising multiple overlapping photographs and structure from motion algorithms to produce a 3D point cloud representation of the target plot. This point cloud is then converted into an orthoimage consisting of four bands-red, green, blue and vegetation height-which is free from perspective distortions. The approach is trialled in two Eucalypt forests in South Eastern Australia to produce an estimate of change in cover of all vegetation elements following a prescribed burn. Orthoimages are generated with 2.5 mm resolution and classified using object-based image analysis and random forests into broad vegetation and fuel classes. Utilising this approach an overall classification accuracy of 81% is achieved with the resulting estimates of cover agreeing with visual point based interpretation to within 6% across all classes.
Subject Terrestrial Ecology
Forestry Fire Management
Photogrammetry and Remote Sensing
Keyword(s) Object based image analysis
Orthoimage
Percent vegetation cover
Prescribed burning
Structure from motion
DOI - identifier 10.1016/j.ecolind.2018.12.044
Copyright notice © 2018 Elsevier Ltd
ISSN 1470-160X
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