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Why do my raster cells seem to have a 'border'?

Question asked by leftieant76 on Jan 9, 2018
Latest reply on Jan 25, 2018 by gaukel02

Hi

 

I'm at a bit of a loss here. I am attempting to generate a multi-directional hillshade, and the output raster cells seem to have a 'border' around them. I cannot for the life of me work out why and what to do about it.

 

What am I talking about? This:

 

 

The processing history behind this dataset:

 

1 - downloaded 1 second STRM elevation grid from USGS

2 - as SRTM is in an angular coordinate system, I resampled to a 20 x 20m grid (bilinear) - size not a neat match, but I thought it would be ok as the end use was hillshade rather than analysis

3 - as the STRM data is integer rather than floating, I ran Focal Statistics (average over 3x3 neighbourhood) to smooth

4 - down the multidirectional hillshade function, add to Image Analysis window, run the function on my smoothed data

 

The grid / borders only seem to appear on cells that have differing values in the cells adjacent to them.

 

Any ideas on what is causing this and how I can rectify or avoid it?

Many thanks

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