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rcarne1
04-21-2008, 04:32 PM
I am having no success trying to do the following and hope somebody more familiar with WAVE's rendering options can get me moving in the right direction.

I want to extract arrays of seafloor depths from the ETOPO2 database and then render these Mercator-like seafloor segments as 3-D curved surfaces as they would appear on the global sphere. The arrays of depth are 601 x 601 and represent 20 degrees of longitude and latitude. Getting the data from ETOPO2 is the easy part.


My approach has been -

POLY_SURF - obtain a vertex_list and polygon_list using the 2D array obtained from ETOPO2.

I then replace the x and y positions in the vertex_list (integers between 0 and 600) with actual longitudes and latitudes of the seafloor segment. That gives me a 3x 361201 array of longitudes, latitudes, and depths.

CONV_TO_RECT - I convert values in the vertex_list to rectangular values after scaling the ocean depths to an Earth with a radius of 1.0. I use the /Global, and /Degree keywords.

VTKSURFGEN - taking the 3 x 361201 array of points (aka vertex_list) I try to render it only to get various odd objects.

POLY_SPHERE - this looked hopeful and can produce nice sections of a globe but calls insuffient memory errors if the polygon diameter of the globe is more than a few hundred. The 601 x 601 resolution of the depth array is severly reduced when rendered at these lower resultions.

Thinking that I was making some type of error while dealing with the 601x601 array, I set up a simple 4 x 4 grid covering the same range of latitude and with a uniform z of 1. After conversion of the degrees to rectangular coordinates, VTKSURFGEN produces a square surface with a crumpled appearance ( inconsistent transformed z values). It should be trapezoidal and curved.

I'll close by mentioning that I get great 3D surfaces from the 601x601 arrays just using VTKSURFACE. But, I'd really like to get the actual spatial relationships and Earth curvature in my visualization.

Any suggestions?

Thanks.

rwagner
04-22-2008, 09:14 PM
Hi,
Can you give me some idea of the available memory you have on your system? Is this a 32 or 64-bit system? Windows or Unix? I would think that POLY_SPHERE is the obvious choice here. I will try and see how much memory this routine requires.

-Ryan