Friday, October 13, 2017

High Resolution Post-Fire Imagery

Thanks to a generous offer from a contact on the Google Crisis Response team, CalTopo is temporarily displaying high-resolution imagery for portions of the fire-affected areas in Napa and Sonoma counties.  This imagery was taken by DigitalGlobe on Wed the 11th, and although the fires are still ongoing, it provides some degree of insight into what had burned by that point.  While there is a lot of smoke present, in many areas it's clear enough for a house-by-house assessment.

Because the original imagery is false-color infrared (which gives vegetation a strong red tint), I'm converting it to black-and-white to avoid any possible confusion between the red tint and currently burning areas.  I'm told that true-color imagery will be available at some point on Fri, and hopefully I'll be able to upgrade the layer to match.

Available imagery footprints, with fire outlines shown in red.

Step 1: Go to https://caltopo.com/l/16PD

Step 2: Enter your address in the search field at the top of the page and click GO:


Step 3: Use the zoom control at the top left of the map to zoom in:


Step 4: Mouse over the layer selector at the top right (it should read "Hybrid +1"), and in the window that comes up, adjust the "NorCal Fire" opacity slider to expose the pre-fire imagery:


It may also be helpful to temporarily turn on the "Current Fire Activity" checkbox in order to see the fire perimeters:


I've put some temporary infrastructure in place to help handle this project, but if the site is impacted too much, I may need to make some changes.  The shortlink at the top of this article (https://caltopo.com/l/16PD) will always point to the right place - if you share a URL, please share that.

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