Geoinformation for Disaster and Risk Management - ISPRS

Image indexing
Everyday there were tens or even a hundred images
gathered by NDRCC. To quickly search the necessary
image, an index map of incoming images was firstly
created with indexing parameters registered and
linked, such as the satellite name, sensor name,
spatial resolution, observing time.
Data pre-processing
The information extraction processing was based on
the second level image product. The optical images
were processed for geometric precision correction
and ortho-rectification into second level. Similarly,
radar images were filtering, registered and
enhancement to produce second level images. The
standard pre-processing stage guaranteed the
consistency of the images.
Figure 7: Integrated disaster loss
assessment map for Wenchuan
Earthquake
Information extraction
Based on the above prepared data, information of
collapsed houses, landslides, destroyed roads, quake
lakes and other changes to features, the distribution
of evacuation routes and other related disaster
information were extracted (Fig.5, Fig.6), using the
methods of information enhancement and changing
detection. Since the goal was mostly to extract
objects at the scale of metres, the information
extraction was mainly based on high spatial
resolution images with resolutions less than 5m. To
provide effective and timely support information for
disaster emergency rescue and relief, the
information extraction should be completed within
hours after the image were acquired.
Integrated assessment
To give a general loss assessment of the Wenchuan
earthquake, the integrated emergency assessment
map (Fig.7) at county level was produced based on
interpretation of the remote sensing images,
background data and disaster information data. The
assessment of affected people and damaged houses
at different levels were displayed on the disaster
map and used by state councils for reconstruction
and recovery planning.
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