Changes between Version 1 and Version 2 of BovFiles


Ignore:
Timestamp:
11/28/11 13:07:07 (13 years ago)
Author:
Jonathan
Comment:

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  • BovFiles

    v1 v2  
    33= BOV (Brick of Value) files =
    44
    5 BOV files are the easiest way to get fixed grid data into visit.  While the .bov files are what are opened in visit, the actual data itself is in an accompanying unformatted data file.  Each BOV file contains meta data that describes the size, spatial extents, the time, the number of components for each cell, and the name of the actual data file.  Those BOV files always come in pairs - one data file for each bov file.  This is important to keep in mind when transferring files from one folder to another.
     5BOV files are the easiest way to get fixed grid data into visit.  While the .bov files are what are opened in visit, the actual data itself is in an accompanying unformatted data file.  Each BOV file contains meta data that describes the size, spatial extents, the time, the number of components for each cell, and the name of the actual file with the actual data.  Those BOV files always come in pairs - one data file for each bov file.  This is important to keep in mind when transferring files from one folder to another.
    66
    7 Writing to the bov file is fairly straightforward.  See io/io_bov.f90 for an example.  Writing to the data file is a little bit tricky because of the ordering of the fields.
    8 
    9 First the data file has to be opened as unformatted.
    10 
    11 {{{OPEN(UNIT=UNIT_ID, FILE=FileName, status="replace", FORM="unformatted")}}}
    12 
    13 Then to output the data just execute
     7Here is a sample bov file for a 512x512x1 data cube with only 1 component and a spatial extent of 50x50x0
    148{{{
    15 DO i=1,NrComps
    16   WRITE(UNIT_ID) q(:,:,:,i)
    17 END DO
     9  TIME:   0.100000000000000
     10  DATA_FILE: Mass_along_3_00001.dat
     11  DATA_SIZE:          512         512           1
     12  DATA_FORMAT: DOUBLE
     13  VARIABLE: projection
     14  DATA_ENDIAN: LITTLE
     15  CENTERING: zonal
     16  BRICK_ORIGIN:     0.0000000000000000E+00    0.0000000000000000E+00    0.0000000000000000E+00
     17  BRICK_SIZE:     0.5000000000000000E+02    0.5000000000000000E+02    0.0000000000000000E+00
     18  BYTE_OFFSET: 4
     19  DATA_COMPONENTS:    1
    1820}}}
    1921
    20 Note that this is different then
     22Generating a bov file is fairly straightforward.
    2123{{{
    22   WRITE(UNIT_ID) q(:,:,:,:)
     24      OPEN(UNIT=BOV_DATA_HANDLE, FILE=Filename)
     25      WRITE(BOV_DATA_HANDLE,*)  "TIME: ", tnow
     26      write(BOV_DATA_HANDLE,'(A13,A,A4)') "DATA_FILE: ", TRIM(name), ".dat"
     27      WRITE(BOV_DATA_HANDLE,'(A11,3I12)')  "DATA_SIZE: ", shape(data), 1
     28      WRITE(BOV_DATA_HANDLE,*)  "DATA_FORMAT: DOUBLE"
     29      WRITE(BOV_DATA_HANDLE,'(2A)')  "VARIABLE: ", TRIM(varname)
     30      WRITE(BOV_DATA_HANDLE,*)  "DATA_ENDIAN: LITTLE"
     31      WRITE(BOV_DATA_HANDLE,*)  "CENTERING: zonal"
     32      WRITE(BOV_DATA_HANDLE,'(A14,3E26.16)')  "BRICK_ORIGIN: ", lower,0
     33      WRITE(BOV_DATA_HANDLE,'(A12,3E26.16)')  "BRICK_SIZE: ", upper-lower,0
     34      WRITE(BOV_DATA_HANDLE,*)  "BYTE_OFFSET: 4"
     35      WRITE(BOV_DATA_HANDLE,'(A17,I4)')  "DATA_COMPONENTS: ", 4
     36      CLOSE(BOV_DATA_HANDLE)
    2337}}}
    24 because Fortran uses Column Major ordering
    2538
    26 If we want to write a one-liner we have to swap the order by using a transpose
     39Writing to the data file is a little bit tricky because of the ordering of the fields.  The BOV files expect data to be ordered in {{{field-x-y-z}}} format where as you go from byte to byte, the field varies the fastest, then x position, y position, and finally z position.  Since Fortran is Column Major this would work fine if arrays were stored {{{q(field, x, y, z}}}.  However since most arrays in astrobear are stored {{{q(x,y,z,field}}} the data needs to be cycled.  This can be done with a combination of reshape and transpose.
    2740
    2841{{{
    29   WRITE(UNIT_ID) transpose(reshape(q(:,:,:,:), (/size(q)/NrComps,NrComps/)))
     42  WRITE(UNIT_ID) transpose(reshape(q(:,:,:,:), (/size(q)/nFields,nFields/)))
    3043}}}
    3144
     45Note that if there is only 1 field, then there is no need to transpose
     46{{{
     47  WRITE(UNIT_ID) q(:,:,:,1)
     48}}}
    3249
    33 The {{{.bov}}} file contains information about the data as well as the location of the actual data file {{{.dat}}} which contains the raw unformatted binary data.  Visit will only recognize the {{{.bov}}} files.
     50Or if the data set is a single field in 2D
     51{{{
     52  WRITE(UNIT_ID) q(:,:)
     53}}}