[Proj] Problem about egm96 geoid hight calculation

[Yutaka KURASHINA]

Dear all,

I use proj.4(4.8.0) and egm96 geoid data below.

   http://download.osgeo.org/proj/vdatum/egm96_15/egm96_15.gtx
     Last modified 15-Feb-2014 08:15

I'm trying to calculate egm96 geoid height with cs2cs.
But I could not get the height at boundary of the geoid data.

At first I ran a command below.

$ cs2cs +proj=latlong +geoidgrids=./egm96_15.gtx +to +proj=latlong <<EOF
heredoc> 0 0 0
heredoc> EOF
0dE     0dN 17.162

This works well. But, the next command didn't.

$ cs2cs +proj=latlong +geoidgrids=./egm96_15.gtx +to +proj=latlong <<EOF
heredoc>     0  90 0
heredoc>     0 -90 0
heredoc>   180   0 0
heredoc>  -180   0 0
heredoc> EOF
Rel. 4.8.0, 6 March 2012
<cs2cs>: while processing file: <stdin>, line 1
pj_transform(): point not within available datum shift grids
*       * 0.000
Rel. 4.8.0, 6 March 2012
<cs2cs>: while processing file: <stdin>, line 2
pj_transform(): point not within available datum shift grids
*       * 0.000
Rel. 4.8.0, 6 March 2012
<cs2cs>: while processing file: <stdin>, line 3
pj_transform(): point not within available datum shift grids
*       * 0.000
Rel. 4.8.0, 6 March 2012
<cs2cs>: while processing file: <stdin>, line 4
pj_transform(): point not within available datum shift grids
*       * 0.000


Is there anything wrong in the commands?
I would like to ask for advice.

Thank you in advance.

Yutaka Kurashina