Re: reading in binary data

Joe,

For interpolation purposes, terrain geogrid data tiles have a border
around them (the tile_bdr=3 in the index file) so the dimensions are
actually 1206x1206. For your tile file size that will give:

1206 x 1206 x 2 = 2908872 bytes

Mike

-- 
============================================
Michael Barlage, PhD
Project Scientist
Research Applications Laboratory
National Center for Atmospheric Research
barlage@ucar.edu -- (303) 497-8420
On 10/28/2011 09:40 AM, Hahmann, Andrea N. wrote:
> Hi Joe
> 
> In this cases I think it is better to write a fortran wrapper.  BTW, I
> have heard of others reading/writing these files.  Maybe sending a message
> to the WRF users group could be useful.
> 
> Regards, Andrea
> ----
> Andrea N. Hahmann
> Senior Scientist
> Wind Energy Division
> Risø DTU
> 
> Technical University of Denmark
> Risø National Laboratory for Sustainable Energy
> Frederikborgvej 399, P.O. Box 49
> 4000 Roskilde, Denmark
> 
> Direct +45 4677 5471
> Mobil: +45 2133 0550
> ahah@risoe.dtu.dk
> http://www.risoe.dtu.dk
> 
> 
> 
> 
> On 10/28/11 5:23 PM, "Joe Grim" <grim@ucar.edu> wrote:
> 
>> Hi Dave,
>>
>> Thank you for your help.  I think I'm getting on the right track.  I have
>> found out that this file was written out by a C subroutine
>> (write_geogrid.c)
>> within the WPS geogrid code.  Even though I hardly know any C, I think
>> that
>> I will eventually arrive at a solution.
>>
>> By the way, when I try the "file" command, I get the name of the file in
>> return, followed by ": data".
>>
>> Joe
>>
>> -----Original Message-----
>> From: Dave Allured [mailto:dave.allured@noaa.gov]
>> Sent: Thursday, October 27, 2011 3:57 PM
>> To: Joe Grim; ncl-talk@ucar.edu
>> Subject: Re: reading in binary data
>>
>> Joe,
>>
>> Scratch that factoring suggestion, it was a bad idea in this case.
>> The discrepancy of 28872 bytes can not be explained by either of two
>> simple formats that might be read or written by Fortran.  That
>> strange number suggests that metadata such as coordinates may be
>> included.
>>
>> What are the chances that your file is *not* Geogrid binary format,
>> but rather WPS intermediate format, or Netcdf, or one of the other
>> formats in the WRF users guide?  That file size would be a better
>> match for some of these.
>>
>> http://www.mmm.ucar.edu/wrf/users/docs/user_guide/users_guide_chap3.html#_
>> Wr
>> iting_Meteorological_Data
>>
>> What do you get from the command "file <filename>" ?
>>
>> --Dave
>>
>> On 10/27/2011 12:18 PM, Dave Allured wrote:
>>> There is a general writeup on how to figure out Fortran binary, at
>>> the bottom of this NCL page.  Try factoring the file size 2908872,
>>> and see if it makes sense:
>>>
>>>     http://www.ncl.ucar.edu/Applications/r-binary.shtml
>>>
>>> --Dave
>>>
>>> On 10/27/2011 12:13 PM, Joe Grim wrote:
>>>> Hi Dennis,
>>>>
>>>> 2908872, so it is barely over 1200x1200x2=2880000.
>>>>
>>>> Thanks for your help.
>>>>
>>>> Joe
>>>>
>>>> On 10/27/2011 12:08 PM, Dennis Shea wrote:
>>>>> What is the size of the file in bytes?
>>>>>
>>>>> %>   ls -l file_name
>>>>>
>>>>> Is it 1200*1200*2 or 1200*1200*4 ?
>>>>>
>>>>> Or are there 'extra' bytes?
>>>>>
>>>>> ===
>>>>> The defuult in fortran is to write 'sequentail' mode
>>>>> which *silently* prepend and postpends extra bytes.
>>>>>
>>>>>
>>>>> On 10/27/11 12:00 PM, Joe Grim wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I've been trying to read in some FORTRAN-formatted binary data using
>>>>>> fbindirread, but have been unsuccessful thus far.  The data is
>> described
>>>>>> by the following:
>>>>>>
>>>>>> type = continuous
>>>>>> signed = yes
>>>>>> projection = regular_ll
>>>>>> dx = 0.00833333
>>>>>> dy = 0.00833333
>>>>>> known_x = 1.0
>>>>>> known_y = 1.0
>>>>>> known_lat = -89.99583
>>>>>> known_lon = -179.99583
>>>>>> wordsize = 2
>>>>>> tile_x = 1200
>>>>>> tile_y = 1200
>>>>>> tile_z = 1
>>>>>> tile_bdr=3
>>>>>> units="meters MSL"
>>>>>> description="Topography height"
>>>>>>
>>>>>> I understand most of this (e.g., the data is 1200x1200, each data
>>>>>> point
>>>>>> requires 2 bytes, the value can be positive or negative), but when I
>> try
>>>>>> to read in the data using fbindirread, I can't find a single way that
>>>>>> works:
>>>>>> e.g., HGT_M = fbindirread(geog_data_path+filename,0,-1,"short")
>>>>>>
>>>>>> If someone knows how this works, would you please help me out?  I
>> really
>>>>>> appreciate it!
>>>>>>
>>>>>> Joe Grim
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