[Gdal-dev] Merging bands (was: pct2rgb.py)

[Mario Beauchamp]

Hi,

On Thu, 14 Oct 2004 14:26:43 -0400, Gillian Walter <gillian.walter at atlantis-scientific.com> wrote:

>Does openev 1.82 include the latest compose.py tool?  If it does, I think the
>compose and export tools could also be used to do the merge (load the three
>images up in openev, launch the compose tool, set the three output bands, display
>the result, then run the export tool- it should be able to export the vrt lines
>created by the compose tool).  This is more steps than gdal_merge, but avoids the
>command line for those who prefer gui's.

May I suggest a method I added to gvviewwindow.py to merge bands without using the compose tool?

It goes like this:

def open_rgb_gdal_dataset(self, datasets):
    import vrtutils
    
    self.make_active()

    vrt_opts = vrtutils.VRTCreationOptions(3)
    vrt_tree = vrtutils.serializeCombinedDatasets(datasets,vrt_opts)
    ds = gdal.OpenShared(gdal.SerializeXMLTree(vrt_tree))
    rgbDS = gview.manager.add_dataset(ds)
    rgbDS.SetDescription('VRTDataset')

    red_raster = gview.manager.get_dataset_raster(rgbDS,1)
    green_raster = gview.manager.get_dataset_raster(rgbDS,2)
    blue_raster = gview.manager.get_dataset_raster(rgbDS,3)

    rgb_layer = gview.GvRasterLayer(red_raster, rl_mode = gview.RLM_RGBA)
    rgb_layer.set_source(1,green_raster)
    rgb_layer.set_source(2,blue_raster)
    rgb_layer.set_name('RGB layer')

    self.viewarea.add_layer(rgb_layer)
    self.viewarea.set_active_layer(rgb_layer)
    self.rawgeo_update()

The resulting VRTDataset can then be exported normally. Note that 2 other methods are needed to open
3 files at once. A dialog for selecting the bands would have been nice but I didn't feel it was
necessary at that time :)

def rgb_open_cb(self, *args):
    self.make_active()
    dlg = filedlg.FileDialog(dialog_type=filedlg.FILE_OPEN, multiselect = 1 )
    dlg.ok_button.connect('clicked', self.rgb_files_open_by_name, dlg)
    dlg.show()

def rgb_files_open_by_name(self, widget, dlg, *args):
    filenames = dlg.get_filenames()
    if len(filenames) != 3:
        gvutils.error('3 files needed for band merging')
        return
    datasets = []
    for file in filenames:
       datasets.append(gview.manager.get_dataset(file))
    
    self.open_rgb_gdal_dataset(datasets)


Does this procedure look good to you guys? Would it be better to use the new
vrtutils.VRTDatasetConstructor class (great class!) to do this?

Thanks for your attention.
--
Mario B.