Distance Between Terrain Points

Can you offer some guidelines or things to keep in mind here? I imagine the user should adjust this number when switching between 3-second or 1-second data. Specifically:

1) How does this relate to matrix size?

2) How does this value impact accuracy/speed of calculations?

3) If using 1-second data, would using 30m here be logical?

4) How is terrain data used/interpreted if distance between data points is > or < the resolution of the terrain data being used? i.e. If 1-second data is used, what happens if you choose something other than 30 meters?

Thanks,

-Josh