Selon leaffan <[email protected]>: I actually missed your first post before changing the example, but your arguments make sense. You're free to improve the page with your variant also : it's a wiki !
Dimensions, spatial extent and resolutions are all linked between them, so there are different point of views possible like the various gdalwarp options show : -tr to set the resolution, or -ts to set the output size. > > Hej again, > > > Even Rouault wrote: > > > > Selon "Simon (Vsevolod) Ilyushchenko" <[email protected]>: > > > > Yes, your proposal is better and deals with non-square pixel. So I've > > changed > > the wiki page accordingly. Thanks! > > > > the consideration of non-squared pixels could have been easily be included > in the previous wiki example as well. All one would have had to do is > changing it the following way: > > # setting pixel resolution (for example) > xres = 0.5 > yres = 0.75 > > # calculating resulting raster size from extent and desired pixel size > # using math.ceil to make it a little bit bigger than actually necessary > tiff_width = int(math.ceil(abs(src_extent[0] - src_extent[1]) / xres)) > tiff_height = int(math.ceil(abs(src_extent[3] - src_extent[2]) / yres)) > > # creating new raster layer > raster = gdal.GetDriverByName('GTiff') > dst_ds = raster.Create(tiff, tiff_width, tiff_height, 1, gdal.GDT_Byte) > > # creating raster geo transform based on upper left corner and desired pixel > # resolution and assigning it to raster dataset > # now dealing with non-squared pixels > raster_transform = [src_extent[0], xres, 0.0, src_extent[3], 0.0, -yres] > dst_ds.SetGeoTransform(raster_transform) > > I still beg to differ to that defining the dimensions of the resulting > raster dataset is the setting to be primarily adjusted when converting > vector to raster data. Aliasing and the general *accuracy* of the raster > representation are first and foremost influenced by the pixel resolution, > which in turns determines the size of my resulting dataset. When doing > vector to raster conversions in the past, I have never thought of how large > my result needs to be, but always questioned myself how to define the pixel > resolution to i.e. avoid nasty aliasing effects on diagonal lines. > But that's just my experience and opinion of course. > Regards, > Markus > > -- > > ******************************************************** > Dipl.-Kartograph Markus Reinhold > > Chair of Geoinformatics, Geohydrology and Modeling > Friedrich-Schiller-University Jena > Löbdergraben 32 > D - 07743 Jena > Germany > > Phone.: (+49)(0)3641 / 9 488 65 > E-Mail: [email protected] > ******************************************************** > > -- > View this message in context: > http://n2.nabble.com/Incorrect-blank-raster-example-in-the-FAQ-tp3765775p3771824.html > Sent from the GDAL - Dev mailing list archive at Nabble.com. > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
