ibg.html

有限元学习研究用源代码(老外的),供科研人员参考

<title> Grid Generation and Geometry Description
</title>
<h1> Grid Generation and Geometry Description
</h1>
Here are some examples for the possibilities to use IBG.
 <P>
More information about the IBG package is available via anonymous
<a href = "file://ftp.iaas-berlin.de/pub/ibg">ftp</a>.

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Example: R&uuml;gen Island (Germany):
<br>

<IMG ALT="R&uuml;gen" SRC="ruegen_grid.gif">
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This grid was created in the following way:

 <UL>

 <LI> A <A HREF="ruegen.gif">picture</A> of the region around
R&uuml;gen was obtained with the <A
HREF="http://pubweb.parc.xerox.com/map">Xerox PARC Map Viewer</A> and
the xv grab function.

 <LI> xpaint was used to manipulate this picture:
 <UL>
 <LI> At first, a <A HREF="ruegen2col.gif">picture</A> which contains
only two colors was created.
 <LI> The two segments have been subdivided into six more convex
subsegments with slightly different colors.
 </UL>

 <LI> The resulting <A HREF="ruegen6col.ppm">picture</A> has been
saved in the PPM format.

 <LI> The program <A
HREF="file://ftp.iaas-berlin.de/pub/ibg/examples/ibgmainpix.c">
ibgmainpix.c</A> was used to create the grid (with ca. 40 000 points
in 24 sec. on a VAX 4000/90).

 </UL>

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The geometry description also allows to describe complex 3D geometries
containing intersections without explicite specification of the
intersection lines. So, the grid<br>


<IMG ALT="Rohr" SRC="rohr.gif">

 <br> was created using the program <A
HREF="file://ftp.iaas-berlin.de/pub/ibg/examples/ibgmain3line.c">
ibgmain3line.c </A>

 <br> Segments with nontrivial topology also can be simply
created. The grid<br>


<IMG ALT="Hole" SRC="hole.gif">

<br> was created using the program <A
HREF="file://ftp.iaas-berlin.de/pub/ibg/examples/ibgmain3hole.c">
ibgmainhole.c </A>
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Using elevation data obtained from the
<A HREF="DEM.html">1-degree USGS Digital Elevation Models</A> we have created the
following elevation profile:<br>

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Great Falls East:<br>

<IMG ALT="falls-profile" SRC="falls-profile.gif">

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Grand Canyon East:<br>

<IMG ALT="canyon-profile" SRC="canyon-profile.gif"><br>

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An YDL output possibility allows to use the SGI powerflip program for
visualization:<br>

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Great Falls East:<br>
<IMG ALT="falls-powerflip" SRC="falls-powerflip.gif">

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Grand Canyon East:<br>

<IMG ALT="canyon-powerflip" SRC="canyon-powerflip.gif">
<IMG ALT="canyon-powerflip2" SRC="canyon-powerflip2.gif">