Help / Q&A


ArcGIS Pro Layer files available for highlighting vegetation gain or loss with HazMapper data:

Veg. Loss layer file (*.lyrx, download)

Veg. Gain layer file (*.lyrx, download)

Questions & Answers… Have a question? Please e-mail us.

Q: After an event happens, how long do I have to wait for post-event imagery? A: For the Sentinel-2 A/B satellites, the repeat cycle is 10 days for each satellite or 5 days when combined. Depending upon the time elapsed since the Sentinel-2 satellites passed over your area of interest, it could be as short as a one day wait. The Landsat 7 & 8 satellites have a repeat cycle of 16 days. Of course, if the area is cloudy when the satellite passes over, the acquired scene may not be that useful, and you will have to wait for additional image acquisitions.

Sentinel-2 Acquisition Plans

Landsat 7 & 8 Acquisition Plans

Q: Why does HazMapper not seem to work for high latitude regions? A: It does, but if you are trying to use it for locations above 60° N or 56° S latitude, and you input a Slope threshold (deg) value in the Parameters window, HazMapper will fail to return any of the output image files (Hillshade, Greenest Pre, Greenest Post, or Relative NDVI change). This is because the slope threshold depends on the existence of the SRTM-30 m DEM for the location that you are analyzing, and this DEM does not extend above 60° N or 56° S latitude. HazMapper stops processing when it can not execute an input slope threshold value because the underlying DEM does not exist. To fix this, simply delete the Slope threshold value from the Parameters window and press the Update button. HazMapper will happily get back to work.

Q: Why does the Download function not work properly? A: It probably does. The Download function will fail if too large an area is visible on the screen. If it does not work properly, try zooming in on the area of interest with a click or two and press the Download button again. The download size is put in place by Google. We are working on an error message for the next update of HazMapper that will notify the user if the download extent is too large. Until then, the zoom-in trial-and-error method should do the trick.

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