[issm-support] Issues with meshing..

[Larour, Eric (385J)]

Derrick, 

I'm also puzzled as to why bang is giving you an error. I am right now
working 
on reproducing the bug from your procedure document. Will keep you posted
as soon
as I find the bug. Should not be long.

For further reference, please include issm-support at issm.ess.uci.edu in
your reply 
all, so other ISSM folks can also help you :)

Eric L. 





On 12/31/12 12:17 AM, "djl22" <djl22 at psu.edu> wrote:

>Hi,
>
>I think I found a way through it. I tried working with the original
>data, which provides surface velocity over the entire Greenland ice
>sheet projected in polar stereographic. I used geotiffread to import the
>GEOTIFF image. I used exptool to draw my domain as a sub-region
>(Jakobshavn area) from the imported image and set the initial resolution
>of my mesh at 2km (2000m). The output mesh looks about right. I then
>extract the pixel center coordinates using the pixcenters command:
> >>info=geotiffinfo(filename);From
> >> [x,y] = pixcenters(info);
>
>This gets my coordinates for pixel centers. I then have to flip my (y)
>coordinates because the InterpFromGridToMesh command complains that the
>values should be decreasing. After doing so I run the
>InterpFromGridToMesh command and here things get odd. I notice that in
>your examples the velx and vely variables in your Searise and jakobshavn
>examples are entered in the InterpFromGridToMesh command as the
>transpose of these variables, is this correct? (i.e.
>vx=InterpFromGridToMesh(x1,y1,velx',md.mesh.x,md.mesh.y,0);).
>If I enter my velocity grid as such then I get an error. if I enter
>without the transpose the command seems to work, but then I get an odd
>message when I use the output from the Interp command in the following
>bamg command. I get:
>
>Anisotropic mesh adaptation
>Error message: 'field' should have 930 rowsError using BamgMesher
>
>At this point I'm lost as to why its not working. When I attempted to
>run your Searise example as indicated, I ended up with the same exact
>error in running bamg (I ran the lines of code provided directly from
>the example). I also go tthis error when I ran the Searise example:
>Error message: Input parameter of class single not supported yetError
>using InterpFromGridToMesh
>
>  when I ran 
>vx=InterpFromGridToMesh(x1,y1,velx',md.mesh.x,md.mesh.y,0);...in this
>case I converted the input variables x1, y1 and velx, vely to double
>(x1=double(x1), etc...) was this necessary to get it to work? The
>command worked after doing this which means ISSM could not recognize the
>data type "single" as oppose to "double"
>
>at any rate, i'm now stuck at bamg where I'm attempting to use the
>velocity i assume were interpolated to my initial mesh within my custom
>domain to refine my initial mesh which would ideally create finer mesh
>grids near the margins of Jakobshavn than outside of the margins....
>
>Thanks so much for the assistance....
>
>
>On 12/29/2012 3:04 AM, Larour, Eric (385J) wrote:
>> Dear Derrick,
>>
>> I think the issue is that when you plotted your surface velocities in
>> matlab (before calling exptool
>> on it), you did not specify the x and y coordinates of your image.
>>
>> Typically, in matlab, one does:
>>
>> imagesc(velocity) where velocity is a matrix. This will get you
>> coordinates in scene coordinates.
>>
>> For your example, what you need to do is:
>> imagesc(x,y,velocity),
>> where x=0:(xmax-xmin)/m:xmax and
>>        y=0:(ymax-ymin)/n:ymax
>>
>> and m,n is the size of the velocity matrix.
>>
>> If you do this, you will recover from exptools the true vertex
>> coordinates.
>>
>> Tell me how it goes!
>>
>> Thanks!
>> Eric L.
>>
>>
>>
>> On 12/28/12 11:58 PM, "Derrick Lampkin" <djl22 at psu.edu> wrote:
>>
>>> Greetings,
>>>
>>> I recently attended the ISSM workshop and found it useful. I'm
>>>attempting
>>> to use the system to model a system in the Jakobshavn outlet basin. I
>>> have been using your Jakobshavn example as a template. The exception is
>>> I'm using a base of surface velocity data derived from NSIDC (Joughin
>>> data set). I have imported a surface velocity grid as GEOTIFF into
>>>matlab
>>> and I use the exptool to draw the outline of my domain on top of this
>>> base map. The map is in the polar stereo graphic projection but when I
>>> create the initial mesh using triangle at the nominal resolution of the
>>> data (500 m), the grid spacing was not nearly as dense as expected. I
>>> inspected the domain file I created and the vertices coordinates are in
>>> scene coordinates (row/column) values and not the projected
>>>coordinates ,
>>> therefore the mesh spacing are not reasonable and do not correspond to
>>> the specified resolution I indicate in the triangle command. How might
>>>I
>>> fix this issue?
>>>
>>> Thanks
>>>
>>> derrick j lampkin
>>> __________________
>>> research professor
>>>
>>>                 institute of arctic and alpine research
>>>          
>>>                 university of colorado-boulder
>>>
>>>                    __________________
>>>
>>> email: djl22 at psu.edu
>>>
>>> _______________________________________________
>>> issm-support mailing list
>>> issm-support at issm.ess.uci.edu
>>> http://issm.ess.uci.edu/cgi-bin/mailman/listinfo/issm-support
>
>
>-- 
>derrick j lampkin
>__________________
>research professor
>
>                 institute of arctic and alpine research
>                 university of colorado-boulder
>adjunct
>                   department of geoscience
>                   pennsylvania state university
>                    __________________
>
>email: djl22 at psu.edu
>web: http://www.geosc.psu.edu/academic-faculty/lampkin-derrick
>