Line of Sight and Viewshed Analysis

[JaredAllen]

I have an img raster which is projected into South_America_Lambert_Conformal_Conic. I am attempting to enable the "Use Earth Curvature" to calculate a Line of Sight or Viewshed. However, this option is disabled in both UIs. I have read that I need to establish a z-unit within the constraints of a projected coordinate system. My current projection system is "projected" and I have re-projected it and set the Z Coordinate system to EGM96_Geoid. Additionally, I made sure that my general environments were set to "Enable" z units. However, after all of this the options for "Use Earth Curvature" is still "grayed out"/"disabled".

Please... any help or direction on what I need to fix to enable z-units within my raster dataset so that I can incorporate the curvature.

[EricRice]

Jared,

Convert your raster data to ESRI GRID format.  In windows, navigate to the GRID (represented by a folder with the GRID name).   A GRID is composed of many files.  You want to open and edit the file, "prj.adf".  There should be an entry for Units already; maybe even ZUnit.  If ZUnits is not there add it so it looks similar to below.

Projection    WGS_1984_UTM_Zone_11N
Datum         WGS84
Spheroid      WGS84
Units         Meter
Zunits        Meter

Make sure the observer projection and the GRID projection are the same.  It should work once ZUnits is defined.

Regards,
Eric