Brent, Bruce, others:
I would like to second Bruce's comments. I have spent a great amount of time
writing small scripts to convert between shapfiles/GRASS vectors into GMT
vector format. While this has been an interesting challenge of my programming
abilities, I have long wished for GMT vector support in GDAL/OGR. I have been
considering writing commands specific to GRASS for dealing with vector/raster
output, and indeed, with the help of others, a nearly functioning raster
export tool is available for GRASS -- however a solution built-in to GDAL/OGR
would be optimal for obvious reasons.
In regard to Bruce's comment about how to best retain attributes: This has
prevented me from seeking a more general conversion of geodata into GMT,
requiring some sort of classification and symbolizing in GRASS and then
exporting to GMT vector format. Unless one could pre-classiffy a shapefile /
PGsql table, and then convert to GMT using that one classified attribute for
symbolizing features- things could get complicated. Bruce's idea to extend
the GMT format by including attributes on the flag line might be a good
approach... Another possible approach would involve GMT's other applications
reading other vector formats...
Cheers,
Dylan
On Tuesday 11 April 2006 08:40 am, Bruce Raup wrote:
Hi Brent,
I think it would be great to add the GMT multi-segment ascii file format
to OGR. Others have pointed out that there are other tools for doing
this, but having the format included in OGR would 1) save people from
having to modify shpdump (a shapelib utility) or write a perl program
using Geo::Shapelib (both of which I've done), and 2) elevate the GMT
format, and therefore GMT, to higher visibility in the open source GIS
world.The question arises about what to do about attributes. I have written my
own utilities to translate between GMT and shapefile formats (both
directions), putting the attributes on the "flag line" (usually starting
with '>'). I know that the flag line is used for other purposes by
various GMT programs (e.g. you can specify -G and -W options for psxy on a
per-segment basis by putting them in the flag line), but perhaps a
convention could be established for putting attributes on the flag line
for the purposes of translating between GMT and other formats.Bruce
On 2006-04-08 14:30 -0700, Brent Wood wrote:
> Hi...
>
> I'm discussing the possibility of developing a GMT vector data driver for
> OGR with a programmer interested in undertaking the work.
>
> I don't know how familiar GMT users are with OGR, it is the vector
> equivalent of GDAL, and provides a vector translation/reformatter between
> a range of vector formats. See
> http://gdal.maptools.org/ogr/ogr_formats.html for some info.
>
> GDAL aleady supports GMT netCDF to a limited extent, and provides a
> raster reformatting option.
>
> I'm interested in getting at least OGR shapefile and PostGIS support for
> GMT, so that I can easily plot lines and contours from these in GMT, and
> also convert contours generated by GMT into shapefiles & PostGIS tables.
> I believe this would add some useful vector data management tools to
> support GMT users.
>
> If anyone else is interested in such a capability, I'm interested in
> hearing any wish lists or ideas whch could be included, as well as anyone
> with a few $$ to help fund the development of the software.
>
>
>
> Thanks,
>
> Brent Wood
>
> To unsubscribe, send the message "signoff gmt-help" to
> listserv@hawaii.edu
--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341