[Vis5d-users] VIS5D problem with spikes in surface (land and water)

Hi,

I have installed VIS5D on an SGI machine (32 bit architecture, IRIX 6.5) and have tested out the examples (LAMPS.v5d and SCHL.v5d) and have had some problems with spikes in the surfaces of these pictures. 

I then used a utility from NCAR to reformat MM5 data into VIS5D format and plotted the MM5 data in VIS5D.  The surface spike problem is even worse with MM5 data as shown in the attachment (gif).  In the MM5 view the picture is looking towards the Southeast US and FL.  The problem seems to be worse over water than land with MM5, but I still do get random occurrences of spikes on land too (especially near the edge).  Upon further investigation it seems the spikes appear randomly, yet the height of the spikes always seem to be half of the height of the VIS5D box used in viewing and rotating the data.

Has anyone ever encountered this problem before?  I am wondering if its an installation problem, an Open GL problem, or a source code problem?

Thanks for your time,

Chris Champagne