Fire Danger Forecast index- classification - USGS

Question

I recently downloaded a raster image called Fire Danger Forecast index from USGS - Fire Danger Forecast, and I wanted to get the probability of fire for a set of points I have in another layer, but the thing is that the symbology table does not comes with the data.

I find this very strange because without the table, it is very difficult to classify the whole range of color pixels (0-255) to get the fire probability (0%-100%) for each one.

There is a table available at the website but is a PNG (image) so I can't know where to break exactly.

Does anyone has any workaround about this issue?

Fezter · Answer

I downloaded the tiff file for Large Fire Probability which has 256 pixel values. It appears that from 0-100 are the actual probability for fires. You can see this in the table of contents when you open it in ArcMap.

I think you can probably omit any values between 101 and 250 as they're outside the USA. Values greater than 251 probably have such a low probability of large fires that you could probably assume a probability of zero.

You could use the Con tool to extract values less than or equal to 100 to extract the values with actual probabilities. You'll need the Spatial Analyst extension for that.

Fire Danger Forecast index- classification - USGS

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