<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Dear member of the GMSH support team,<br>
<br>
first I want to admit that I'm rather new to using GMSH to create
meshes.<br>
Anyhow, I want to apply it to automatically create 2D meshes using<br>
available data sets on glacier outlines. These outline files are
provided<br>
externally and exist for each glacier for several time snapshots.
These<br>
outlines typically have many holes inside.<br>
<br>
I succeeded in automating the mesh creation but I ran into the
following<br>
problem. When I choose a too small element sizes, the GMSH command<br>
produces the following error:<br>
<pre>unable to recover an edge ...</pre>
It appears for any Mesh.Algorithm and I tried to adjust
Mesh.RandomFactor (1E-6)<br>
which helps moderately. I also tried to allow
Mesh.CharacteristicLengthFromCurvature<br>
without improvement. For all glaciers, I succeeded in creating a
mesh using coarser<br>
resolutions (relying on the same *.geo file). The problem is that I
need to lower<br>
the resolution too much. Glaciers have a typical extent of several
kilometres and<br>
I would like to use a resolution below 100 metres.<br>
<br>
Therefore, I wonder if I can do any simple <b>pre-processing</b> on
the outline information<br>
which might help in the GMSH creation. Is it worth to exclude points
if they<br>
are too close to their neighbours. Or would some smoothing of the
outline help?<br>
Considering smoothing, I fear that I'll introduce intersections as
outlines can<br>
become rather complex (see figure; glacier has more than 100 holes).
Is there<br>
any setting which might help me further?<br>
<br>
Otherwise, is it possible to refine the coarse grid (in MSH format)
in a <b>post-processing</b> <br>
step using GMSH? I already found some command line version on how to
refine the mesh:<br>
<br>
<a href="http://onelab.info/pipermail/gmsh/2014/008826.html">http://onelab.info/pipermail/gmsh/2014/008826.html</a><br>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<br>
First of all this works but produces some red intersecting triangles
(see *closeup.png from<br>
a GMSH GUI screenshot). I'm nut sure what this means nor how to
remove them.<br>
<br>
I hope you can help me here.<br>
<br>
Thanks in advance.<br>
<br>
Johannes<br>
<br>
ps: for the GEO file I decided to define SPLINES rather than
COMPOUND LINES because<br>
of the element size was more homogeneous<br>
<div class="moz-signature">-- <br>
<font color="#9b9b9b" size="2">_____________________________________<br>
</font> <font color="#0c74b0" size="2"><a
href="http://www.geographie.nat.uni-erlangen.de/personen/johannes-fuerst/"><b>Johannes
J. Fürst</b></a><br>
<font color="#9b9b9b" size="2">Research Scientist<br>
Institute of Geography<br>
University of Erlangen-Nuremberg<br>
Wetterkreuz 15<br>
D-91058 Erlangen, Germany<br>
Ph. +49-(0)9131-85-26680</font> </font></div>
</body>
</html>