I've got a DEM with a resolution of 15m covering a small part of the UK. I am trying to use it calculate slope angle in ArcGIS 10.0. However when running the slope tool the problem I'm having is the Z value is undefined. I have tried using the default 1 and attempted a conversion from feet using 0.3048 both outputs result in giving just two values 0 and the max height. I'm pretty new to all this so I'm not quite sure what else to try? I've done this kind of analysis before with no problems, but this DEM is from a different source.
The spatial reference of the DEM is GCS_WGS_1984 and the format in which I initially encountered the warning about the z value being undefined - I've since converted this into GCS_OSGB_1936 as this is the same projection as the rest of my data and in meters. I tried running the analysis again but getting the same results. On this occasion however I did not receive a warning stating that my Z value was undefined. Changing the coordinate system also sent my DEM out into space.
Any ideas as to what could be going wrong?
Thanks in advance