Using grdimage to plot an image file

Added by Alexander 14 days ago

Hi,

I want to use grdimage to plot the imagefile http://www.ga.gov.au/static/palaeo/timeslice/images/ordovician_2.gif.
The map depicted in this file is has a geographical extent of latitude -8, -44 and longitude 156, 108. The map projection is a Simple Conic Standard with parallels at 18S & 36S and the datum is GDA94.

When I try and plot the image using grdimage on a conic projection with the above parallels the image fails to plot and I return an error:
ERROR: Caught signal number 11 (Segmentation fault) at
0 libgmt.5.dylib 0x000000010117cbac GMT_grdimage + 10280
1 ? 0x0000000000000008 0x0 + 8
Stack backtrace:
0 libgmt.5.dylib 0x0000000100f83e19 sig_handler + 561
1 libsystem_platform.dylib 0x00007fff5b72ab5d _sigtramp + 29
2 ?
0x0000000000000000 0x0 + 0
3 libgmt.5.dylib 0x0000000100f916f1 GMT_Call_Module + 629
4 gmt 0x0000000100f77177 main + 1281
5 libdyld.dylib 0x00007fff5b53f3d5 start + 1

My GMT command is:
gmt grdimage -R108/156/-44/-8 -JD132/0/-18/-36/4.75C -V -K -Dr \
http://www.ga.gov.au/static/palaeo/timeslice/images/ordovician_2.gif \
-P > $ps

I think it has something to do with the image dimensions, but I dont know exactly what, or how to fix it. From grdinfo:
/.gmt/cache/carboniferous_3.gif: Title: Grid imported via GDAL
/.gmt/cache/carboniferous_3.gif: Command:
/.gmt/cache/carboniferous_3.gif: Remark:
/.gmt/cache/carboniferous_3.gif: Pixel node registration used [Cartesian grid]
/.gmt/cache/carboniferous_3.gif: Grid file format: gd = Import/export through GDAL
/.gmt/cache/carboniferous_3.gif: x_min: 0 x_max: 600 x_inc: 1 name: x n_columns: 600
/.gmt/cache/carboniferous_3.gif: y_min: 0 y_max: 476 y_inc: 1 name: y n_rows: 476
/.gmt/cache/carboniferous_3.gif: z_min: 0 z_max: 254 name: z
/.gmt/cache/carboniferous_3.gif: scale_factor: 1 add_offset: 0

Ideally, I would like to plot this image with a pscoast overlay and have the present day coastlines match with the image ones.
Can anyone help me achieve this?


Replies (1)

RE: Using grdimage to plot an image file - Added by Paul 14 days ago

Please post on the GMT forum at https://forum.generic-mapping-tools.org.
Nobody is monitoring these obsolete pages any more.
You cannot apply a map projection to data already projected, use -Jx

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