A COMPARISON OF UAV AND TLS DATA FOR SOIL ROUGHNESS ASSESSMENT
Soil roughness represents fine-scale surface geometry which figures in many geophysical models. While static photogrammetric techniques (terrestrial images and laser scanning) have been recently proposed as a new source for deriving roughness heights, there is still need to overcome acquisition scal...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-06-01
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| Series: | ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | http://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/III-5/145/2016/isprs-annals-III-5-145-2016.pdf |
| Summary: | Soil roughness represents fine-scale surface geometry which figures in many geophysical models. While static photogrammetric techniques
(terrestrial images and laser scanning) have been recently proposed as a new source for deriving roughness heights, there is still
need to overcome acquisition scale and viewing geometry issues. By contrast to the static techniques, images taken from unmanned
aerial vehicles (UAV) can maintain near-nadir looking geometry over scales of several agricultural fields. This paper presents a pilot
study on high-resolution, soil roughness reconstruction and assessment from UAV images over an agricultural plot. As a reference
method, terrestrial laser scanning (TLS) was applied on a 10 m x 1.5 m subplot. The UAV images were self-calibrated and oriented
within a bundle adjustment, and processed further up to a dense-matched digital surface model (DSM). The analysis of the UAV- and
TLS-DSMs were performed in the spatial domain based on the surface autocorrelation function and the correlation length, and in the
frequency domain based on the roughness spectrum and the surface fractal dimension (spectral slope). The TLS- and UAV-DSM differences
were found to be under ±1 cm, while the UAV DSM showed a systematic pattern below this scale, which was explained by
weakly tied sub-blocks of the bundle block. The results also confirmed that the existing TLS methods leads to roughness assessment
up to 5 mm resolution. However, for our UAV data, this was not possible to achieve, though it was shown that for spatial scales of 12
cm and larger, both methods appear to be usable. Additionally, this paper suggests a method to propagate measurement errors to the
correlation length. |
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| ISSN: | 2194-9042 2194-9050 |