OK, we'll meet there but meanwhile have a look at https://docs.generic-mapping-tools.org/latest/gmt.html#j-full
and search for the section -J<proj4>|EPSG:n Unfortunately if your GMT is linked against GDAL 3.xx the EPSG form will not work well because of the axis order (lon, lat swapped). This is fixed in GMT master though. -----Original Message----- From: Rahkonen Jukka (MML) <jukka.rahko...@maanmittauslaitos.fi> Sent: Thursday, November 21, 2019 9:02 PM To: Joaquim Manuel Freire Luís <jl...@ualg.pt>; gdal-dev@lists.osgeo.org Subject: Re: [gdal-dev] Gdal_grid and lake bathymetry Hi, I have converted depth points of a small lake into tab separated CSV and I have generated surface, created contours and now I have an amusing plot of something 😊. I am somewhat lost with projections and actually everything but I think it is better to continue the discussion in the GMT Q&A forum. I will be there next week. -Jukka- -----Alkuperäinen viesti----- Lähettäjä: Joaquim Manuel Freire Luís <jl...@ualg.pt> Lähetetty: torstai 21. marraskuuta 2019 21.42 Vastaanottaja: Rahkonen Jukka (MML) <jukka.rahko...@maanmittauslaitos.fi>; gdal-dev@lists.osgeo.org Aihe: RE: [gdal-dev] Gdal_grid and lake bathymetry Jukka, GMT will have the ability to read ogr formats (code for that is already in base but need to convert to GMT internal data representation and that is far from trivial). Meanwhile, if needed, just use ogr2ogr to convert your data to plain ascii x y z files (binary data is good as well) and feed it surface. Joaquim -----Original Message----- From: Rahkonen Jukka (MML) <jukka.rahko...@maanmittauslaitos.fi> Sent: Thursday, November 21, 2019 4:22 PM To: Joaquim Manuel Freire Luís <jl...@ualg.pt>; gdal-dev@lists.osgeo.org Subject: VS: [gdal-dev] Gdal_grid and lake bathymetry Hi Joaquim, GMT surface probably has all the features that I need. I followed the tutorial and managed to run surface demos, now I just need to learn how to use my own data as input. -Jukka- -----Alkuperäinen viesti----- Lähettäjä: Joaquim Manuel Freire Luís <jl...@ualg.pt> Lähetetty: keskiviikko 20. marraskuuta 2019 0.30 Vastaanottaja: Even Rouault <even.roua...@spatialys.com>; gdal-dev@lists.osgeo.org Kopio: Rahkonen Jukka (MML) <jukka.rahko...@maanmittauslaitos.fi> Aihe: RE: [gdal-dev] Gdal_grid and lake bathymetry The GMT surface program has two (well 3) options that are of interest to this. -One, the -Lu<upper> that serves to limit the upper value in the interpolated grid -The other is the option -D that lets you set a soft-breakline (your shorelines). Soft-breaklines are lines whose vertex end up in the grid nodes closest to them. They are called "soft" in contraposition to the hard-breaklines that do not let the interpolation algorithm go across them. Imagine interpolation a terrain with vertical cliffs. Unfortunately that -D option is missing on the html man page but is described on the surface on line help. -Finally, option -M lets you mask the outside lakes region https://docs.generic-mapping-tools.org/latest/surface.html Joaquim -----Original Message----- From: gdal-dev <gdal-dev-boun...@lists.osgeo.org> On Behalf Of Even Rouault Sent: Tuesday, November 19, 2019 10:13 PM To: gdal-dev@lists.osgeo.org Cc: Rahkonen Jukka (MML) <jukka.rahko...@maanmittauslaitos.fi> Subject: Re: [gdal-dev] Gdal_grid and lake bathymetry On mardi 19 novembre 2019 22:03:29 CET Rahkonen Jukka (MML) wrote: > Hi, > > I would like to get some hints about using gdal_grid or some other > utility for lake bathymetry. What I have is typically rather sparse > point data of depths and the shoreline that includes the islands as in > the attached image. The shoreline and all the area that is not lake > basin should have the altitude of zero in the resulting DEM. It means > that interpolation should not overshoot across the shoreline over the dry > land. > > Gdal_grid seems to miss an option for handling the shoreline so I made > a test by converting the vertices of the polygon rings into depth > points. I also filled area around the lake with a gridded points of > zero altitude but the method feels stupid and tedious and the result > was not so fine when it comes to keep the shoreline and land area near it > totally flat. > Postprocessing with gdalwarp -cutline to set to zero non-lake areas ? -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
