Re: GMT 5 default format

Hi Lester,

I experienced some problems when I went from GMT4 to GMT5. The solution for
me was to set the IO_NC4_CHUNK_SIZE to c(lassic) (as suggested by Florian
Wobbe). Maybe this will sort out your problem?

Andreas


2014-02-06 8:04 GMT+01:00 Lester Anderson <[email protected]>:

> Hello,
>
> I have spotted a slight difference in the default grid formats from v4 to
> v5 and this appears to give some issues loading into other applications:
>
> VERSION 5
> black1_emag2b_RTP.grd: Title: Anomaly reducted to the pole
> black1_emag2b_RTP.grd: Command: grdredpol black1_emag2a.grd
> -Gblack1_emag2b.grd -T2013 -W1 -F45/45 -V
> black1_emag2b_RTP.grd: Remark:
> black1_emag2b_RTP.grd: Gridline node registration used [Geographic grid]
> black1_emag2b_RTP.grd: Grid file format: nf = GMT netCDF format (32-bit
> float),COARDS, CF-1.5
> black1_emag2b_RTP.grd: x_min: 20 x_max: 50 x_inc: 0.0333333333333 name:
> longitude [degrees_east] nx: 901
> black1_emag2b_RTP.grd: y_min: 35 y_max: 50 y_inc: 0.0333333333333 name:
> latitude [degrees_north] ny: 451
> black1_emag2b_RTP.grd: z_min: -1385.10412598 z_max: 3309.81860352 name: nT
> black1_emag2b_RTP.grd: scale_factor: 1 add_offset: 0
> black1_emag2b_RTP.grd: format: netCDF-4 chunk_size: 129,151 shuffle: on
> deflation_level: 3 <------
>
> VERSION 4
> black1_emag2b_RTP_v2.grd: Title: Grid computed inside Mirone
> black1_emag2b_RTP_v2.grd: Command:
> black1_emag2b_RTP_v2.grd: Remark: File written from Matlab
> black1_emag2b_RTP_v2.grd: Gridline node registration used [Geographic grid]
> black1_emag2b_RTP_v2.grd: Grid file format: nf = GMT netCDF format (32-bit
> float), COARDS, CF-1.5
> black1_emag2b_RTP_v2.grd: x_min: 20 x_max: 50 x_inc: 0.0333333333333 name:
> longitude [degrees_east] nx: 901
> black1_emag2b_RTP_v2.grd: y_min: 35 y_max: 50 y_inc: 0.0333333333333 name:
> latitude [degrees_north] ny: 451
> black1_emag2b_RTP_v2.grd: z_min: -1385.10412598 z_max: 3309.81860352 name:
> z [unknown]
> black1_emag2b_RTP_v2.grd: scale_factor: 1 add_offset: 0
> black1_emag2b_RTP_v2.grd: format: classic <------
>
> The format reference from the headers are different. With version 4 there
> are no issues loading GMT (netCDF) grids into other applications like
> MagPick or QGIS (1.8 to 2.1), but with version 5 they are considered an
> unknown format, yet still the default format (=nf).
>
> From gmtdefaults:
>
> # I/O Parameters
> #
> IO_COL_SEPARATOR                = tab
> IO_GRIDFILE_FORMAT              = nf
> IO_GRIDFILE_SHORTHAND           = false
> IO_HEADER                       = false
> IO_N_HEADER_RECS                = 0
> IO_NAN_RECORDS                  = pass
> IO_NC4_CHUNK_SIZE               = auto
> IO_NC4_DEFLATION_LEVEL          = 3
> IO_LONLAT_TOGGLE                = false
> IO_SEGMENT_MARKER               = >
> #
>
> Should any parameters above be tweaked?
>
> It is not a big issue as it is easy to change to a format that works in
> other applications, but it is worth noting that the subtle change in the
> format seems to have a big impact, given that everything else is identical.
> In terms of formats, what constitutes the "classic" format in the list
> under grdreformat?
>
> Cheers
> Lester
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