Tracking of Hurricane Sandy, 2012 |
The next step was to prepare data by creating a new file geodatabase containing new mosaic datasets and feature classes. We added the provided pre and post raster images. I ran into some problems getting these images to display, but it finally worked after adjusting my scale and readding the raster images. Using Effects such as the Swipe and Flicker tools we could compare and contrast the pre and post imagery.
We learned how to create attribute domains using the newly created geodatabase's domain tab. We then created a new point feature class for structural damage. Using create features I created a point feature in the PreStorm image for each parcel within the study area. After creating each point I turned on the PostStorm image and used the Swipe effect to look at differences between the images. This enabled me to set the attribute values for the new attribute fields we created in the domain. Working in a 1:400 scale seemed to allow me some detail to make my best judgement on attribute field values. Determining the extent of wind damage was very difficult. From the images, it appeared that most damage was the result of flooding. The
Post Storm imagery was very dark, appearing as if there was a lot of cloud
cover that day. With shadows in the image it was difficult to determine distinct differences between the images. In real life I
suppose you would have access to property appraiser/GIS data that would better
describe the parcels as to whether the structure types were industrial,
government, or residential. Also, determining if a structure was inundated was difficult. Was the building
inundated or just the property? Hard to
tell from the aerial viewpoint if homes were raised up on stilts, pilings or
blocks or on slabs.
Structural Damage Points in Hurricane Sandy Damage Assessment |
Structural Damage Category Count of structures within distance
categories from the coastline
0-100m 100-200m 200-300m___
No Damage 0 0 1
Affected 0 1 15
Minor Damage 0 3 7
Major Damage 0 27 21
Destroyed 12 9 2__________
Total 12 40 46__________
Parcels
that were closest to the coast received the most damage. All of the structures on parcels within 100m
of coastline were “destroyed” in my assessment.
Structures in the 200m buffer parcels were either destroyed or had
major damage more than structures in the 300m buffer.
We performed attribute transfer mapping to assign parcel data to the structure feature points and then learned how to display labels showing some of the parcel attribute fields.
We performed attribute transfer mapping to assign parcel data to the structure feature points and then learned how to display labels showing some of the parcel attribute fields.
This final lab assignment was very long and covered many new tools in ArcGIS. Each lab always reminds me of the power and knowledge that GIS can provide.
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