[Qgis-user] Selecting rasters with vector layer

Wed Mar 5 05:11:19 PST 2014

Hi Asher,
GeoTIFFs can be compressed considerably but they still end up a bit larger
than ECW's.
For example we have aerial photography:
ECW: 22.7GB
JP2: 26.4GB
GeoTIFF: 31.2GB

So the GeoTIFF (actually an image pyramid) is about 50% larger, but is also
better quality and faster loading.

Cheers,
Jonathan

On 5 March 2014 10:44, Asher Kamiraze <asher.kamiraze at gmail.com> wrote:

> Thank you Eric,
>
> I had to chose FME to save the ECW. My third party software supports other
> formats, but TIFF files are huge, so it is not a viable solution.
>
>
> 2014-03-04 17:07 GMT+01:00 Eric Goddard <egoddard1010 at gmail.com>:
>
>> Hi Asher,
>>
>> Sorry, I didn't read the full GDAL page regarding ECW support
>> (http://www.gdal.org/frmt_ecw.html). ECW is a proprietary format owned
>> by intergraph. GDAL allows reading and writing of ECW files, but in
>> order to write ECW files you have to have a licensing key from
>> Intergraph. On Linux, when configuring the the ECW plugin it asks for
>> the key, and if the user doesn't have one it is configuring in
>> read-only mode. I'm assuming you used the OSGeo4Win installer, which I
>> think configures the ECW support as read only by default. If you do
>> have a key, I'm not sure how you would go about setting up GDAL ECW
>> support to recognize it.
>>
>> From the gdal ECW page:
>> The ECW 4.x SDK from ERDAS is only free for image decompression. To
>> compress images it is necessary to build with the read/write SDK and
>> to provide an OEM licensing key at runtime which may be purchased from
>> ERDAS.
>>
>>
>> Does the third party software you have to use not support any other
>> formats?
>>
>> On Tue, Mar 4, 2014 at 3:41 AM, Asher Kamiraze <asher.kamiraze at gmail.com>
>> wrote:
>> > Eric,
>> >
>> > I just tried to create a VRT from all ecw images in a folder.
>> Unfortunately,
>> > it does not work, the command line seems to be rejected when there are
>> too
>> > many input files. The problem also appear if directly using the
>> gdalbuildvrt
>> > from the command line. The only solution I found was to build an
>> > input_file_list with the following command:
>> >
>> > cd <to_my_ecw_folder>
>> > dir /b *.ecw > listin_ecw.txt
>> > gdalbuildvrt -input_file_list listin_ecw.txt all_ecw.vrt
>> >
>> > Then, if I try to save the cropping result as an ECW file, I got the
>> > following error:
>> >
>> > Output driver `ECW' not recognised or does not support
>> > direct output file creation. The following format drivers are configured
>> > and support direct output:
>> > GeoRaster: Oracle Spatial GeoRaster
>> > VRT: Virtual Raster
>> > GTiff: GeoTIFF
>> > NITF: National Imagery Transmission Format
>> > HFA: Erdas Imagine Images (.img)
>> > ELAS: ELAS
>> > MEM: In Memory Raster
>> > BMP: MS Windows Device Independent Bitmap
>> > PCIDSK: PCIDSK Database File
>> > ILWIS: ILWIS Raster Map
>> > SGI: SGI Image File Format 1.0
>> > Leveller: Leveller heightfield
>> > Terragen: Terragen heightfield
>> > netCDF: Network Common Data Format
>> > HDF4Image: HDF4 Dataset
>> > ISIS2: USGS Astrogeology ISIS cube (Version 2)
>> > ERS: ERMapper .ers Labelled
>> > RMF: Raster Matrix Format
>> > RST: Idrisi Raster A.1
>> > INGR: Intergraph Raster
>> > GSBG: Golden Software Binary Grid (.grd)
>> > GS7BG: Golden Software 7 Binary Grid (.grd)
>> > PNM: Portable Pixmap Format (netpbm)
>> > ENVI: ENVI .hdr Labelled
>> > EHdr: ESRI .hdr Labelled
>> > PAux: PCI .aux Labelled
>> > MFF: Vexcel MFF Raster
>> > MFF2: Vexcel MFF2 (HKV) Raster
>> > BT: VTP .bt (Binary Terrain) 1.3 Format
>> > LAN: Erdas .LAN/.GIS
>> > IDA: Image Data and Analysis
>> > GTX: NOAA Vertical Datum .GTX
>> > NTv2: NTv2 Datum Grid Shift
>> > CTable2: CTable2 Datum Grid Shift
>> > ADRG: ARC Digitized Raster Graphics
>> > SAGA: SAGA GIS Binary Grid (.sdat)
>> >
>> > The generated command line by QGIs is:
>> >
>> > gdalwarp -q -cutline "F:\\MY_SHP_PATH\\Commune_Aix-en-Provence.shp"
>> > -crop_to_cutline -of ECW F:\MY_VRT_PATH\Toutes_dalles_13.vrt
>> > "F:/MY_OUTPUT_PATH/crop.ecw"
>> >
>> > It does not seem to be a "\" "/" issue, since if I choose a .vrt output
>> it
>> > works fine.
>> >
>> > Any idea on how to solve the problem?
>> >
>> > I am running QGIS 2.2.0 on 64 bits windows.
>> >
>> > Regards
>> >
>> >
>> >
>> > 2014-03-04 1:51 GMT+01:00 Eric Goddard <egoddard1010 at gmail.com>:
>> >
>> >> Yes, you should be able to choose ECW from the files of type drop down
>> in
>> >> the output file selection dialog and select ECW.
>> >>
>> >> Eric
>> >>
>> >>
>> >> On Mon, Mar 3, 2014 at 4:48 PM, Asher Kamiraze <
>> asher.kamiraze at gmail.com>
>> >> wrote:
>> >>>
>> >>> Thanks Eric, sounds really good. Is there a way to save the resulting
>> >>> file (clipped) as an ECW file? I need to process it later with a 3rd
>> party
>> >>> software.
>> >>>
>> >>> Regards
>> >>>
>> >>>
>> >>> 2014-03-03 23:26 GMT+01:00 Eric Goddard <egoddard1010 at gmail.com>:
>> >>>
>> >>>> Hi asher, if you go to raster -> miscellaneous, there is a menu entry
>> >>>> called build virtual raster catalog. You can use that to virtually
>> mosaic
>> >>>> all of your ECW files. This tool creates a new file you can load in
>> as a
>> >>>> raster that references all of the individual ECW files to display
>> them
>> >>>> seamlessly in qgis without having to spend the time to actually
>> mosaic all
>> >>>> of them together. Load the resulting vrt file into qgis using add
>> raster and
>> >>>> clip the vrt to your polygon layer using raster -> extraction ->
>> clipper.
>> >>>>
>> >>>> Eric
>> >>>>
>> >>>> On Mar 3, 2014 3:53 PM, "Asher Kamiraze" <asher.kamiraze at gmail.com>
>> >>>> wrote:
>> >>>>>
>> >>>>> Hi all,
>> >>>>>
>> >>>>> I have a set of more than 200 ecw rasters that I can easily load in
>> >>>>> QGIS. I also have a vector polygon layer which bounds an area
>> covering a
>> >>>>> part of the area covered by the whole set of rasters. What I would
>> like to
>> >>>>> do is to extract only, the raster which are intersected by the
>> vector
>> >>>>> boundary. As a final goal, I would like to only mosaic thoses
>> images. I did
>> >>>>> not found a way to easily do this in QGIS. Any idea on how to
>> achieve this?
>> >>>>>
>> >>>>> As a workaround, I have opened only the raster intersecting the
>> vector,
>> >>>>> and would like to mosaic them. However, it does not seem to be a
>> function in
>> >>>>> QGIS ready to mosaic all opened (or selected) rasters. Any idea on
>> how to
>> >>>>> automate the process?
>> >>>>>
>> >>>>> Hope you could help
>> >>>>>
>> >>>>> Regards
>> >>>>>
>> >>>>> _______________________________________________
>> >>>>> Qgis-user mailing list
>> >>>>> Qgis-user at lists.osgeo.org
>> >>>>> http://lists.osgeo.org/mailman/listinfo/qgis-user
>> >>>
>> >>>
>> >>
>> >
>>
>
>
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