Help for ExtrudeMesh

Extension of Elmer in computational glaciology
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Help for ExtrudeMesh

Post by gelujqy » 18 Nov 2014, 09:55

Hi, Dear Elmer users!

I have some problems in extruding a 2D mesh into 3D. I use ExtrudeMesh which is coming from here ... xtrudemesh

below in my attachment are two files (please unzip first).

"Amery2D" contains the 2D mesh files for the Amery Ice Shelf of Antarctica (the plan view).

"DEM" contains the upper and lower ice surface elevation in this region ( and respectively).

The DEM file (both and are regular gird data with resolution of 500m in a rectangle. the x coordinate is from 1602500m to 2302500m, the y coordinate is from 502500m to 902500m.

so my goal is to extrude my 2D mesh to get a 3D mesh which contains the ice body of the Amery Ice Shelf.

I have two questions I am not very sure about:

(The 1st Question)
I check the command option of ExtrudeMesh, and it seems if I use DEM in my extrusion, then the argument of 'noval' is mandatory, which is the values representing invalid data entities in DEM's. But in my DEM file, there's no invalid data and every data is true. I tried to set the 'noval' argument at 0 or -9999 or whatever, but it seems I couldn't get the correctly extruded 3D mesh.

I think I used the command "./ExtrudeMesh Amery2D Amery3D 10 10 1 0 0.1 0 DEM 3000 2 0" (assume "Amery3D" is the output directory, 10 layers in extrusion, 10m as default extrude depth, 0.1 as percentage of boundary layer, 3000m as the cutoff distance, 2 as the exponent in the weighting factor, and other argument as default).

so could someone please tell me how should I set the 'noval' argument in my command or is there error in my command? I just couldn't get a right extrusion.

(The 2nd Question)
The dataset in "DEM" (both and is regularly located in a rectangle, with its x coordinate ranging from 1602500m to 2302500m and y coordinate ranging from 502500m to 902500m. but the extent of Amery Ice Shelf (my 2D mesh file) is smaller than this and it's an irregular polygon, which is approximately located from 1670000m to 2260000m (x coordinate) and from 600000m to 850000m (y coordinate).

so will the mismatchment between the extent of my 2D mesh and my DEM data lead to my extrusion failure?

still I am not familiar with Elmer/Ice and its tools so I am really sorry if I overlooked or misunderstood anything.

I will be very appreciated for any help!
upper and lower surface of ice elevation
(94.46 KiB) Downloaded 1154 times
Amery Ice Shelf Plan View
(35.49 KiB) Downloaded 1069 times

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Re: Help for ExtrudeMesh

Post by gagliar » 18 Nov 2014, 10:59


I would suggest, if you are starting a new modelisation, to move to the internal extrusion to create your 3d mesh from a 2d footprint. You can have a look at the Tete Rousse example from the last Elmer/Ice course done in Reykjavik last month ( ... es:courses).

Hope it helps

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Re: Help for ExtrudeMesh

Post by gelujqy » 21 Nov 2014, 08:36

Dear Olivier, I am so grateful for your fast reply, yeah I have found that material, thanks so much! :D

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