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I download USGS GAP Analysis and use a polygon to clip raster from that GAP Analysis. I am wondering why there is a strange looking color when you clipped the raster. If you zoom in, you can see myraid colors, but when zoom out you see some white spotty areas.

I can't insert 2 saved image for you to review it, but here is the link you can see it .

Gap Analysis example

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up vote 1 down vote accepted

This is probably 'by design', though there are ways around it. When you're zoomed out, each pixel is really just an approximation, and has to represent some neighborhood of cells in the actual data.

I believe the default in ArcGIS in this case is to have No Data values always 'win' if one or more is present within the resampled cell, hence the large number of supposedly empty cells at scales other than 1:1.

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