On Mon, Mar 8, 2010 at 5:42 PM, Pierre Racine <pierre.rac...@sbf.ulaval.ca> wrote: > > >4.- Add default geotransform to GDAL empty dataset: {0.0, 1.0, 0.0, 0.0, > >0.0,1.0 }; (I can't get > >geotransform from WKT Raster Band) > > Why? You can get all the parameters with (in order): > rt_raster_get_x_offset(), rt_raster_get_pixel_width(), > rt_raster_get_x_rotation(), rt_raster_get_y_offset(), > rt_raster_get_y_rotation(), rt_raster_get_pixel_height()...
Yes, I can. It was testing code. But you're right. > > >1.- I'm testing this code with really simple raster, and I'm confused. For > >example: > >* 2x2 32 bits signed int raster, with "1" in all cells. The result: > >POLYGON((0 0, 0 2, 2 2, 2 0, 0 > >0)). I was expecting POLYGON((0 0, 0 1, 1 1, 1 0, 0 0)) > > The result is correct since the pixel size is 1, the raster dimension is 2x2 > and there is only one group of pixel sharing the same value. Ok, Thanks for confirmation. > > >* the raster > >from > >http://trac.osgeo.org/postgis/attachment/wiki/WKTRaster/SpecificationWorking01/WKTRasterEnvelopeC > >onvexHullAndShape.gif. The result: > >POLYGON ((3 1,3 2,2 2,2 3,1 3,1 6,2 6,2 7,3 7,3 8,5 8,5 6,3 6,3 3,4 3,5 3,5 > >1,3 1)) > >POLYGON ((3 3,3 6,6 6,6 3,3 3)) > >POLYGON ((5 1,5 3,6 3,6 6,5 6,5 8,6 8,6 7,7 7,7 6,8 6,8 3,7 3,7 2,6 2,6 1,5 > >1)) > >POLYGON ((0 0,0 9,9 9,9 0,0 0),(6 7,6 8,3 8,3 7,2 7,2 6,1 6,1 3,2 3,2 2,3 > >2,3 1,6 1,6 2,7 2,7 3,8 3,8 > >6,7 6,7 7,6 7)) > > > >Something strange here? Am I doing things right? > > It look good to me. What is wrong? Mmm... ok, it may be only my impression. > > >2.- I'd like to store the pixel value in each polygon. Is a good idea to > >create a field in the layer > >to store pixel value? > > You are supposed to return the value for each polygon in a "wktgeomval set" > as stated in the specs. This way the SQL caller can decide what to do with > the value. Isn't that what you did? Yes, I did this. The point is I was trying to label each polygon with its pixel value (GDALPolygonize allows this). Then, in a loop, I get all the features of the layer written by GDALPolygonize and store the exported WKT polygon and the px value in a wktgeomval structure. Sounds good? > > >3.- From a GDAL RasterBand, I can fetch the owning dataset handle > >(GDALGetBandDataset).I think it > >could be useful to get the WKT Raster handle from a WKT RasterBand too... Am > >I right? > > rt_band_get_data()? No, I mean getting the raster that contains this band, from the band struct itself, like GDALDatasetH GDALGetBandDataset(GDALRasterBandH hBand ) from GDAL C API (or GDALRasterBand::GetDataset() from GDAL C++ API) > > Pierre Thanks Pierre! Jorge _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev