anbul 2004
al band for
prrelated to
1ifer forest.
the conifer
number of
gher in the
1e SPOI-S
pping dark
a and used
1ce method
s used for
je used but
age.
nages are
n matching
1e new and
of interest
iphic map,
linearised
percentiles
rest mask,
d from the
n, seasonal
1imised.
difference
resolutions
if nearest
introduced
mage used.
have the
nable the
nt within 3
Boards are
ion of new
lemand for
NBF has a
e detection
on of new
tection of
ssible also
r-cut areas
e planning
e are no in
lapping. À
purpose of
west scene
band data
and of the
d between
Id be used
on of the
Itancously
Xt feasible,
reas were
ion in the
used.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B1. Istanbul 2004
4. RESULTS AND DISCUSSION
41 Resolution merge examples for interpretation
Compared to Landsat-7 or SPOT-4 images, additional forestry
features can be detected, identified and mapped in SPOT-5 data.
The resolution merged colour images, both the standard merged
2.5 m product from SpotImage and the 2.5 m merged including
the SWIR band, made by Metria, clearly shows the presence of
seed trees left on the new clear cut area. Adapted contrast
stretch for the purpose of identifying these areas should be used.
This is shown in Figure 6, where individual trees can be seen
within the cut area. On the other hand, other types of forestry
activities can be detected and identified in Figure 3 and Figure
4, where the line patterns in the right part if the image are
thinnings performed by thinning harvester machines, and are
easily clearly detected and identified in the high resolution
panchromatic SPOT-5 data (2.5m, Sm) but can also be detected
in the 10 m data with some difficulties.
e + AR
t
A at > 3 d i ict
Figure 3 Resolution merge of SPOT-5 10m multispectral and
2.5m panchromatic data. Standard merged product from
SpotImage. (Band 3=r, 2=g
CE SR 1 cie
Itispectral and
Figure 4 Resolution merge of SPOT-5 10m mu
2.5m panchromatic data using the normalised difference
modified HFM technique including the SWIR band.
(Band 3-r, 47g, 2-b)
4.2 Clear cut mapping
An example of the single SWIR band difference image is shown
in Figure 5. In field validation campaigns performed, all areas
mapped with a minimum size of 0.5 ha where found, although
the area estimate error varies. The use of SPOT-5 merged data
is clearly giving better area estimates, although this has not been
validated by ground measurements at this time. Another clear
benefit, according to user requirements, is the better area
contours mapped with the SPOT-5 data.
Figure 5 SWIR single band difference image between |
SPOT-5 2002 and Landsat-7 ETM- 1999 scenes.
Contour from threshold with 10m pixels.
Buy utilising the resolution merged data with 2.5 m or 5 m pixel
size, performing the change detection directly between the
merged SPOT-5 SWIR band and Landsat-7, the contour of the
clear cut area can be mapped more precisely. This is shown in
Figure 6. The black contour is mapped from 2.5 m data and is
compared to the area mapped with 10 m pixels in purple..
p áo "td
Figure 6 SWIR single band difference image between
2.5 m resolution merged SPOT-5 2002 and
Landsat-7 ETM+ 1999 scenes.
4.3 Seed trees mapping
Seed tree density classification was performed by thresholding
in the SPOT-5 SWIR band, within the borders of the previously
mapped clear cut areas. Panchromatic data were not used in this
test. Seed trees can not be identified by visual interpretation in
the 10m colour data, but the density of seed trees is correlated
to the SWIR band intensity. As this information is intended to
be used for stratification and planning of field visits, the
validation was performed at object level. Figure 7 shows the
result of the classification and the arrow is showing the look
direction of the ground photo in Figure 8. -
Sed
Figure 7 Density of seed trees left mapped in 3 classes.
