/8, 2012
um-level zoom
lisation system
n and a photo-
. Figure 5 (b)
1 from medium
lisation system
ed in a single,
ail information
dual rock pools
of micro-algae
'eriwinkles and
he mosaic such
n the rock (see
gy
rimary types of
cosystems with
e infeasible us-
napping allows
y, vertical posi-
ope and aspect
aphic mapping
present during
variables such
f near-infrared
:ts on plant and
ulations at sev-
efore and after
not possible to
us reducing the
‚ost method al-
atial scales and
illowing for ap-
cially valuable
h as seasonality
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
from human impacts such as construction, pollution or climate
change in a statistically robust way.
The method presented here is not limited to rocky intertidal sub-
strata but can also be used for various applications on intertidal
mud flats. Conditions on intertidal mud flats can change over an
interval of a few minutes - large changes in sediment properties
can occur including dewatering of the sediment and the migration
of microphytobenthos to the surface (Perkins et al., 2003). These
changes can have significant impacts upon sediment stability over
the course of a single tidal cycle. Due the dynamic nature of inter-
tidal mudflats combined with the relatively slow pace of conven-
tional field sampling make it impossible to make measurements
of sediment properties across space which are truly independent
of changes in time. Our method, by enabling large amounts of
data to be acquired in a snapshot of time, at specific times in the
tidal cycle, enables independent measurements to be made. Ap-
plications include the determination of impacts of structures on
sediment properties or the effects of spillage of contaminants e.g.
algicides, pesticides or fertiliser (Murphy and Tolhurst, 2009) on
phytobenthos.
4 CONCLUSIONS AND FUTURE WORK
In this paper, we have described a photogrammetric pipeline that
was developed for constructing high-resolution, 3D, photo-realistic
terrain models of intertidal areas using multiple low-altitude im-
ages collected from a consumer-grade digital camera suspended
by a kite platform. Dynamic intertidal ecosystems by their na-
ture can change rapidly at the scale of minutes to years making it
almost impossible to acquire data that describe changes which oc-
cur spatially independently of temporal changes using field-based
sampling. The methods presented acquire colour and topographic
information across a hierarchy of spatial scales in a very small
time interval, enabling changes in spatial distributions of assem-
blages to be determined independently of temporal changes.
The appropriate sampling of plant and animal assemblages in
highly dynamic ecosystems such as intertidal environments is an
enduring problem. Ongoing work is focusing on mapping and
registering multiple datasets collected over subsequent low tides
to track the dynamics of biota in the area over varying timescales.
Additionally, ongoing work is focusing on acquiring near-infrared
images using a modified consumer grade camera that will compli-
ment the visual images and provide additional data such as vege-
tation, chlorophyll and algal biomass indices.
ACKNOWLEDGEMENTS
This work was supported in part by Australian Research Council
and the New South Wales State Government.
REFERENCES
Aber, J., Aber, S. and Pavri, E., 2002. Unmanned Small-format
Aerial Photography from Kites for Acquiring Large-scale, High-
resolution, Multiview-angle Imagery. In: ISPRS Commission
VFIEOS 2002 Conference Proceedings.
Aber, J., Sobieski, R., Distler, D. and Nowak, M., 1999. Kite
Aerial Photography for Environmental Site Investigations in
Kansas. Kansas Academy of Science 102(1-2), pp. 57—67.
Agarwal, S., Snavely, N., Seitz, S. and Szeliski, R., 2010. Bundle
Semen in the Large. In: European Conference on Computer
ision.
Artigas, F. and Pechmann, I., 2010. Balloon Imagery Verification
of Remotely Sensed Phragmites Australis Expansion in an Urban
Estuary of New Jersey, USA. Landscape and Urban Planning
95(1), pp. 105-112.
Barber, C., Dobkin, D. and Huhdanpaa, H., 1996. The Quick-
hull algorithm for convex hulls. ACM Trans. on Mathematical
Software 22(4), pp. 469—483.
Beis, J. and Lowe, D., 2003. Shape indexing using approximate
nearest-neighbor search in high-dimensional spaces. In: Com-
puter Vision and Pattern Recognition, pp. 1000-1006.
Frahm, J., Pollefeys, M., Lazebnik, S., Gallup, D., Clipp, B.,
Raguram, R., Wu, C., Zach, C. and Johnson, T., 2010. Fast ro-
bust large-scale mapping from video and internet photo collec-
tions. ISPRS Journal of Photogrammetry and Remote Sensing
65(1), pp. 538-549.
Furukawa, Y. and Ponce, J., 2010. Accurate, Dense, and Robust
Multi-View Stereopsis. IEEE Trans. on Pattern Analysis and Ma-
chine Intelligence 32(8), pp. 1362-1376.
Guichard, F., Bourget, E. and Agnard, J., 2000. High-resolution
remote sensing of intertidal ecosystems: A low-cost technique
to link scale-dependent patterns and processes. Limnology and
Oceanography 45(2), pp. 328-338.
Horn, B. K. P, 1987. Closed-form solution of absolute orien-
tation using unit quaternions. Journal of the Optical Society of
America 4(4), pp. 629—642.
Johnson-Roberson, M., Pizarro, O., Williams, S. and Mahon,
L, 2010. Generation and Visualization of Large-scale Three-
dimensional Reconstructions from Underwater Robotic Surveys.
Journal of Field Robotics 27(1), pp. 21—51.
Murphy, R. and Tolhurst, T., 2009. Effects of experimental ma-
nipulation of algae and fauna on the properties of intertidal soft
sediments. Journal of Experimental Marine Biology and Ecology
379(1-2), pp. 77-84.
Murphy, R., Tolhurst, T., Chapman, M. and Underwood, A.,
2008. Spatial Variation of Chlorophyll on Estuarine Mudflats
determined by Field-based Remote Sensing. Marine Ecology
Progress Series 365(1), pp. 45-55.
Perkins, R., Honeywill, C., Consalvey, M., Austin, H., Tolhurst,
T. and Paterson, D., 2003. Changes in microphytobenthic chloro-
phyll a and EPS resulting from sediment compaction due to de-
watering: opposing patterns in concentration and content. Conti-
nental Shelf Research 23, pp. 575-58.
Sklaver, B., Manangan, A., Bullard, S., Svanberg, A. and
Handzel, T., 2006. Rapid Imagery through Kite Aerial Photogra-
phy in a Complex Humanitarian Emergency. International Jour-
nal of Remote Sensing 27(21), pp. 4709-4714.
Snavely, N., Seitz, S. and Szeliski, R., 2008. Modeling the world
from Internet photo collections. International Journal of Com-
puter Vision 80(2), pp. 189-210.
Torr, P. and Murray, D., 1997. The Development and Compari-
son of Robust Methods for Estimating the Fundamental Matrix.
International Journal of Computer Vision 24(3), pp. 271-300.
Underwood, A., 1994. On beyond BACI: Sampling designs that
might reliably detect environmental disturbances. Ecological Ap-
plications 4(1), pp. 3-15.
