August 24, 2017

Hack Map

This map is a product of FIU’s GIS Center and the Department of Journalism + Media.

Click image to access.

 

The visualization of the sea level rise is based upon the State of Florida Division of Emergency Management LiDAR ProjectLAS Dataset hosted by the FIU International Hurricane Research Center (see details at http://digir.fiu.edu/Lidar/lidarNew.php). It is intended to project results of “static” sea level rise, not taking tidal effects in consideration. The web visualization of the “static” sea level rise map (details here) is developed by FIU’s Geographic Information Systems (GIS) Center.

This application uses elevation data from the Google Elevation Service. The elevation value is interpolated from actual elevation measurements at the four nearest available locations. The horizontal resolution is the distance between these points. Please note that we use Google Elevation to show the elevation of the address entered by the user, but we do not use Google Elevation to calculate the visualization of sea-level rise.

The data and maps in this tool illustrate the scale of potential flooding, not the exact location, and do not account for erosion, subsidence, or future construction. Water levels are shown as they would appear during the highest high tides (excludes wind driven tides), also known as MHHW (mean higher high water – see http://co-ops.nos.noaa.gov/datum_options.html for a definition).

The visualization of the “static” sea level rise map is created using following method:

  1. There are six layers available at each foot level between 1 and 6. The opacity of all layers defaults to 0.
  2. If the slider is set between 0 and 1 then the opacity of the 1 foot layer is set linearly. That is, for a desired opacity of op (in our case 0.8) and a setting of 0.6 feet, op1 = 0.6 * op.
  3. If the slider is set higher than 1 then two layers are on at a time.
  4. The higher layer is set as above and the lower layer is set to maintain the overall opacity, since the higher layer covers all of the same area as the lower plus additional areas.
  5. So if the slider is set to 1.15, then op2 = 0.15 * op and op1 = 1 – (( 1 – op) / (1 – op2)). Maintaining the overall opacity leads to a smooth transition as the slider is moved.