Notes on buffers used by BAGIS

• • The AOI Min/Max elevation values on the AOI Info and maps forms are calculated from the unbuffered AOI

  • The AOI Min/Max elevation values on the Site Scenario and Psuedo Site form are calculated from the buffered AOI. Generating a pseudo-site with an elevation constraint will fail if the unbuffered AOI values are used because some pixels will fall out of the calculation (beyond range).

  • When raster layers are clipped to an AOI (except for PRISM) the envelope from the buffered AOI is used (aoib_v)

  • When analysis layers are generated (elevation zones, slope zones, snotel, and snow course zones) the envelope from the buffered AOI is used (aoib_v). This means that the maps will show data beyond the AOI boundary represented in black.

  • When generating the represented area layers (snotel, snow course, combined), the analysis area is restricted to the unbuffered AOI. The represented area(s) on the title page is the area of these respective polygons. This is also true of the Excel tables in BAGIS-PRO.

  • The pseudo-sites algorithm uses the buffered AOI as the analysis mask when running the Euclidian distance tool and calculating constraint layers. However, the optimal site must be within the unbuffered AOI boundary

  • In the Site Scenario tool, the represented area(s) are calculated using the unbuffered AOI boundary

  • Why buffer an AOI ?

• • BAGIS has the capability to set different buffer distances for AOI, Snotel, Snow Course, and PRISM layers. It is recommended to set the buffer to a minimum of 1000 meters for PRISM layers due to the lower resolution.

Default buffer distances

• PRISM Precipitation: 1 km (1,000 meters)

• DEM: 100 meters

• SNOTEL and Snow Course site: 5 km

See the BAGIS-PRO user's manual for Notes on Buffers Used by BAGIS-PRO.