Why do raster datasets need to be resampled when panning and zooming in ArcGIS Pro?

BillGrimm

This might be a silly question. I understand that resampling is the process of interpolating new cell values when a raster is transformed to a new coordinate space or cell size. However, why is there an option to set the resampling method in the Rendering group of the Image Layer/Raster Layer/etc. tabs in ArcGIS Pro? In other words, why do you need to resample when simply panning and zooming a raster (as opposed to running it through a geoprocessing tool)?

Robert_LeClair

The Resampling setting in the Rendering group controls display resampling (on-the-fly)—how ArcGIS Pro draws your raster to the screen when the raster grid does not map 1:1 to your current view.

Even when you “just pan and zoom,” Pro often has to compute a new value/color for each screen pixel because:

• Zooming changes the pixel-to-pixel relationship: at most scales, one screen pixel corresponds to a fraction of a raster cell or multiple raster cells, so Pro must decide how to sample/average values to draw the image.
• The map may be in a different coordinate system than the raster: if so, Pro is also doing an on-the-fly reprojection for display, which requires interpolation.
• The goal is visualization quality vs speed, and the “best” method depends on whether the raster is categorical (classes) or continuous (imagery/elevation).

That’s why the method matters for display:

• Nearest neighbor: fastest; best for discrete/categorical rasters; preserves original values but can look blocky/jagged.
• Bilinear: smoother for continuous rasters; alters values (can blur).
• Cubic: sharper than bilinear but slower; can introduce values outside the input range.
• Majority: often used for discrete rasters to smooth class “speckle.”

Hope this helps!