PE&RS May 2016 - page 337

The multispectral bands and the panchromatic band of the
WorldView-2 image were fused using the Gram-Schmidt pro-
cedure (Laben and Brower, 2000), to produce a pan-sharpened
multispectral image with a 0.5 m resolution for both seasons. The
pan-sharpened images of the summer and winter seasons were
registered with a root mean square error less than 0.1 pixels.
A pan-sharpened multispectral image subset of 2,500
×
3,500 pixels of the Beijing area was selected (Plate 1). The
subset covered the Peking University campus and the sur-
rounding areas, with large clustered trees, water bodies, and
fragmented grassland as well as impervious surface. The area
includes different land use types: commercial, residential,
and public service areas. In summer, streets and sidewalks are
obscured by the foliage of trees (Plate 1A), whereas in winter,
these streets and sidewalks underneath deciduous trees are
exposed as impervious surface (Plate 1B).
Tianjin Area and Data
The phenological summer in the Tianjin area occurs usually
from approximately 12 May to 25 September, while winter
lasts from approximately 01 November until 10 March of the
following year (Yang, 1997). Vegetation includes coniferous
forest, needle broadleaf mixed forest, deciduous broadleaf for-
est, meadow, saline vegetation, and grass. The trees along the
streets are mostly deciduous arbors including Fraxinus Velu-
tina (
Fraxinus velutina Torr
), pagoda tree (
Sophora japonica
),
and Oriental plane tree (
Platanus orientalis
), which have a
Plate 1. The WorldView-2 images of Beijing area acquired in (A) September 2012, and (B) February 2011 (Bands Red, NIR1 and Green as R, G, and B).
Plate 2. The WorldView-2 images of Tianjin area acquired in (A) September 2014, and (B) February 2015 (Bands Red, NIR1 and Green as R, G and B).
T
able
1. W
orld
V
iew
-2 S
atellite
D
ata
A
cquisition
I
nformation
for
the
T
wo
S
tudy
A
reas
Acquisition
season
Acquisition
date
Off-nadir
view angle
Satellite
azimuth
Satellite
elevation
Beijing
Summer
14 September
2012
14°
237.2°
74.1°
Winter
01 February
2011
19.3°
250.5°
68.1°
Tianjin
Summer
09 September
2014
8.9°
244.3°
79.9°
Winter
05 February
2015
18.1°
222°
69.4°
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
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