When I calculate slope and hillshade from a dem the results I get look weird... like gridlines. In the case of slope it looks like it is calculating the centre of each cell as flat (zero slope) and making the boundaries between slopes relatively steep. With hillshade the cell centres have a high value and the boundaries between cells relatively low values (see attchments). I'm currently using ArcView 9.3 sp1. I was thinking there might be something wrong with the DEM - but when I tried redoing slope and hillshade for a dem that I had successfully dones these for back in early 2009 I got the same problem.
If anyone out there has had this problem and can shed some light on how to fix it I would be very grateful.
