noaa-ocs-modeling / OCSMesh

OCSMesh is a mesh preparation tool for coastal ocean modeling applications.
https://noaa-ocs-modeling.github.io/OCSMesh/
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Ignored island meshing #41

Open SorooshMani-NOAA opened 2 years ago

SorooshMani-NOAA commented 2 years ago

Discussed in https://github.com/noaa-ocs-modeling/OCSMesh/discussions/34#discussioncomment-4032202

This issue used to show up for some Pacific islands I tried meshing in the past. Since it was hard to package the issue into a small domain test I never elevated it to Darren to see if it's related to Jigsaw.

Originally posted by **acroucher** Nov 3, 2022 ... I have just noticed one more thing, I'm not sure if it's related to the rest of this discussion or not. There are some small islands which are being omitted from the mesh. In general, the mesh is picking up small islands much better now, using the coastline shapefile to define the geometry rather than contouring the DEM. But there are still some islands that are being left out. It seems to be happening mostly with small islands in deeper water. They are typically a few hundred metres across, so they should be representable using the specified hmin (50 m). The mesh size is around hmin at the locations of these islands, so the hfun is probably correct. Here is a particular example (the polygon shows the island's coastline): groper I tried just meshing the area around this island by itself - I created a circular boundary of radius 3 km around the centre of the island. When I do that, the island is meshed correctly: groper2 Any idea what could cause this? I wondered if perhaps the mesh post-processing was sieving these islands out (does this maybe depend on the maximum element size in the mesh?), so I tried experimenting with passing a sieve parameter to the driver.run() call, but that didn't seem to help.
SorooshMani-NOAA commented 2 years ago

Hi @dengwirda I noticed this issue in the past when I was meshing a small domain with a bunch of islands. When meshing some of the islands in my domain would be ignored (meshed over), while some others were not. I tried removing any "extra" islands so that I can create a small test case to pass to you, but then after removing the other islands it started honoring my island of interest's boundary.

At the time (2021) I thought it's a one off issue. But yesterday one of OCSMesh users noticed the exact same issue with similar behavior. I still don't know how to package this issue for you. Do you have any suggestion on how to investigate it or how to pass a test case to you to see if it's a Jigsaw issue or not?

Thanks for your time!