Changes between Version 2 and Version 3 of CatalogueForQIS

Timestamp:

Apr 2, 2012, 2:08:35 AM (12 years ago)

Author:

pcav

Comment:

--

CatalogueForQIS

@@ -1 @@
-When you have a set of raster that are a mosaic. If really useful a catalogue to use all ads un unique raster.
-Qgis is capable to use the VirtualCatalog of gdal.[[BR]]
-To create a catalogue (on windows) usable from qgis 1.9, you can create a file ascii with a list of all the raster with their paths. Like this:[[BR]]
+When you have a set of raster that are a mosaic. If really useful a catalogue to use all as a single raster.
+Qgis is capable to use the GDAL !VirtualCatalog.[[BR]]
+To create a catalogue (on windows) usable from qgis 1.9, you can create an ASCII file with a list of all the raster with their paths, e.g.:[[BR]]
 
 {{{
@@ -11 +11 @@
 ...
 }}}
-(save the file as "my_list.txt for example)
+(save the file as e.g. "my_list.txt")
 [[BR]]
 
@@ -17 +17 @@
 To create the catalog use this call.[[BR]]
 
+{{{
 gdalbuildvrt.exe -resolution average -allow_projection_difference -addalpha -hidenodata -input_file_list my_list.txt -overwrite my_catalog.vrt [[BR]]
+}}}
 
-After the catalog is create it could be used from qgs. But the gdalbuildvrt don't compute the statistics of the rasters in the catalogue and unfortunately qgis,
-if detect that the stats are not available in the catalog, try to compute they for each raster (ouch!). If the rasters are huge and on a shared remote folder. This step could be more time expensive.[[BR]]
-So is really a good idea to add the stats to the catalogue before use it on qgis :)[[BR]]
-Qgis really need only of min/max nothing else. Also to speed up this step you could use without any problem an approximated stats computing.[[BR]]
-To add this approx-stats to the gdal you can use this simple and smart python code:[[BR]]
+After the catalog is created, it can be used from qgs. But the gdalbuildvrt doesn't compute the statistics of the rasters in the catalogue; unfortunately qgis, if detect that the stats are not available in the catalogue, tries to compute it for each raster (ouch!). If the rasters are huge and on a shared remote folder, this step can take very long.[[BR]]
+So it is really a good idea to add the stats to the catalogue before use it on QGIS :)[[BR]]
+QGIS needs only of min/max, nothing else. So, to speed up this step you could use without any problem an approximated stats computing.[[BR]]
+To add this approx-stats to the catalogue you can use this simple and smart python code:[[BR]]
 
 [Thanks to Giuseppe Sucameli & Faunalia for this smart code]
@@ -67 +68 @@
 
 Save it as "computestat.py" and use it with this sintax:[[BR]]
+
+{{{
 computestats.py -approx my_catalog.vrt
+}}}
 
 et voila!
-Now QGis start fast and smart using the raster catalogue
+Now QGIS starts fast and smart using the raster catalogue.
 [[BR]]
 
-Happy catalog-ing
+Happy cataloguing!
 [[BR]]
 Andrea Peri