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D.8.7) DTED Smoothing

The DTED data used for the assessment of a viewshed from a point in Sussex was not of a particularly resolution and gave rise to some quite 'Minecraftesque' renderings.

In an attempt to smooth this data a Laplace approach was used.

The data points were spread out so that there were three columns and three rows between any data point and its nearest neighbours. These were fixed points whose value would not be changed.

Each cell that was not a fixed point was the sum of the adjacent cells.

This process was performed on every cell for a total of fifty iterations. During each iteration the sum of the data in the cells was calculated. For any given iteration the difference between this value and that of the previous iteration was assessed and expressed as a percentage of the value for the first iteration. After many iterations the differences between iterations became very small, i.e., it was converging on a solution .

The fixed data points are visible but the data is generally smoother.

Allowing the 'fixed points' to 'float' and be affected by neighbouring points, the results (after five iterations are:

Original data:

Smoothed version:

Not clever, but  something to do on a rainy afternoon...