[postgis-users] [Qgis-developer] Fwd: WKTRaster Plugin 0.1

Tue Nov 30 07:20:59 PST 2010

2010/11/30 Maurício de Paulo <mauricio.dev at gmail.com>:
> Yes, the main issue we found was the performance of display. So something
> inside the driver is slowing the reading process done by qgis.
> I took a look at the MODE option. It can be set in the user interface on my
> plugin. I think that a combobox storing "Read whole table" "Read one row"
> and "Read entire database" should pass the right options. Is it the real
> interpretation of this parameter? Any sugestions?
> Best regards,
> Mauricio de Paulo
>

Yes, Basically, one spatial query is executed for each data petition.
That can (must) be improved. I know it.

About the parameter, yes. There is, basically, 3 ways of using the driver:

- Providing only a database name, and optionally, a schema name: The
driver returns all the existent raster tables as subdatasets
- Providing a database name, a table name and optionally, a column
name: The driver returns all the rows of the raster table as a
subdataset. This is, consider each row as a different raster. The same
if you provide "mode=1" as parameter.
- Providing a database name, a table name and "mode = 2": The driver
consider that all the rows of the table are tiles of a bigger raster
coverage, and constructs one raster object based in the whole extent
of all the raster tiles. For now, just working with regularly blocked
rasters.

So, about your combobox, the option "read the entire database" (or
"read one schema") should disable the selection of a table name (it is
the first of the 3 points).

Best regards,

-- 
Jorge Arévalo
Internet & Mobilty Division, DEIMOS
jorge.arevalo at deimos-space.com
http://mobility.grupodeimos.com/
http://gis4free.wordpress.com

P.S.: My mails to QGIS list are rejected, but I think that could be
interesting. I'll subscribe to the list.

>
> 2010/11/30 Jorge Arévalo <jorge.arevalo at deimos-space.com>
>>
>> 2010/11/30 Maurício de Paulo <mauricio.dev at gmail.com>:
>> > I've been using GDAL 1.7 and postgis 1.5.1
>> > Both postgis' windows and ubuntu versions are able to load the rasters
>> > fine.
>> > We've encountered some trouble with what we believe is the "regular
>> > blocking" issue.
>> > wktraster's QGIS plugin and MapServer source were tested on ubuntu 10.04
>> > with ubuntugis binaries.
>> > Perfomance looks like a huge issue at the moment. I didn't investigate
>> > why.
>> > I can probably take look back at this issue when I get back home to my
>> > ubuntu box. I can't test on windows because there is no QGIS compiled
>> > with
>> > gdal 1.7 for windows prebuilt.
>> > This new gdal driver version was included in which gdal release? Maybe
>> > we
>> > can recompile everything and test again.
>> > Best regards,
>> > Mauricio
>> >
>>
>> Yes, the old version of the driver had some known (by me) problems:
>>
>> - Depends on the information stored in "raster_columns" table, in
>> PostGIS installation, and it shouldn't.
>> - Performance. I need to review this. It's a question of PostGIS queries.
>>
>> In October, I commited a new version with some improvements. It's in
>> GDAL trunk since release 20912
>> (http://trac.osgeo.org/gdal/changeset/20912). Anyway, I'd like to
>> improve more things in this driver. The reading process is the big
>> issue right now. The best way to read blocks of data.
>>
>> If you use it, the most important thing is now you need to specify an
>> extra parameter: "mode". Further information here:
>> http://trac.osgeo.org/gdal/wiki/frmts_wtkraster.html
>>
>> Best regards,
>> --
>> Jorge Arévalo
>> Internet & Mobilty Division, DEIMOS
>> jorge.arevalo at deimos-space.com
>> http://mobility.grupodeimos.com/
>> http://gis4free.wordpress.com
>>
>> > 2010/11/29 Jorge Arévalo <jorge.arevalo at deimos-space.com>
>> >>
>> >> Good news! Which version of GDAL/PostGIS are you using? I commited a
>> >> new version of the GDAL driver on October, and included WKT Raster as
>> >> official part of PostGIS on September 26th.
>> >>
>> >> On Mon, Nov 29, 2010 at 9:40 PM, Maurício de Paulo
>> >> <mauricio.dev at gmail.com> wrote:
>> >> > Ok, after a few minutes of implementation here it is. Now the plugin
>> >> > lists
>> >> > the tables from the database and shows some of it's metadata. Now I
>> >> > think
>> >> > it's fully functional. If anyone finds a bug , please tell me.
>> >> > Best regards,
>> >> >
>> >> > On Mon, Nov 29, 2010 at 3:50 PM, Maurício de Paulo
>> >> > <mauricio.dev at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Hi Jorge,
>> >> >> Good news. The plugin wktraster is exactly a tool to connect qgis to
>> >> >> postgis rasters through GDAL and visualize the data.
>> >> >> Stefan asked about the processing. This is something the plugin
>> >> >> doesn't
>> >> >> do.
>> >> >> I've tested with a friend both qgis (with the plugin) and mapserver
>> >> >> loading postgis rasters. Both worked fine, and the only requirement
>> >> >> is
>> >> >> qgis
>> >> >> compiled against gdal 1.7.
>> >> >> I'm interested in updating the plugin this week to work as I've
>> >> >> planned.
>> >> >> It's going to speak for itself.
>> >> >> Best Regards,
>> >> >> Mauricio
>> >> >> Ps.: Anyone willing to help and join this effort is always welcome.
>> >> >>
>> >> >> On Mon, Nov 29, 2010 at 3:45 PM, Jorge Arévalo
>> >> >> <jorge.arevalo at deimos-space.com> wrote:
>> >> >>>
>> >> >>> Hi,
>> >> >>>
>> >> >>> If you want a GDAL version compiled with PostGIS Raster support on
>> >> >>> Windows, you may take a look here:
>> >> >>> http://vbkto.dyndns.org:1280/sdk/
>> >> >>>
>> >> >>> Visualizing PostGIS Raster data via GDAL driver is one of my TODO
>> >> >>> tasks. I don't have too much free time now, but if you're
>> >> >>> interested
>> >> >>> on this topic, and you're going to test it, please let me know.
>> >> >>> There
>> >> >>> are more people interested on that, and I'm providing support to
>> >> >>> some
>> >> >>> of them (not as much support as I'd like, because the time...)
>> >> >>>
>> >> >>> Best regards,
>> >> >>>
>> >> >>> --
>> >> >>> Jorge Arévalo
>> >> >>> Internet & Mobilty Division, DEIMOS
>> >> >>> jorge.arevalo at deimos-space.com
>> >> >>> http://mobility.grupodeimos.com/
>> >> >>> http://gis4free.wordpress.com
>> >> >>>
>> >> >>> 2010/11/29 Stefan Keller <sfkeller at gmail.com>:
>> >> >>> > Ok (I'm cross posting to qgis-developer and postgis-users).
>> >> >>> >
>> >> >>> > I'm still not sure if I did express myself clearly:
>> >> >>> > You say, that under Windows, there's no QGIS compiled against
>> >> >>> > GDAL
>> >> >>> > 1.7/1.8 with PostGIS Raster support?
>> >> >>> >
>> >> >>> > What I finally dream of, is using QGIS to display the results of
>> >> >>> > a
>> >> >>> > SQL
>> >> >>> > query (either as raster or vector) against at least one raster
>> >> >>> > layer.
>> >> >>> > This query contains raster constructors (like ST_Intersection)
>> >> >>> > and
>> >> >>> > operations (like ST_Reclass; see
>> >> >>> > http://trac.osgeo.org/postgis/wiki/WKTRaster).
>> >> >>> >
>> >> >>> > Any suggestions?
>> >> >>> > -S.
>> >> >>> >
>> >> >>> >
>> >> >>> > 2010/11/29 Maurício de Paulo <... at gmail.com>:
>> >> >>> >> Hi Stefan,
>> >> >>> >>
>> >> >>> >> WKTRaster Plugin just repasses the right information to the GDAL
>> >> >>> >> driver.
>> >> >>> >> It's not a new qgis driver.
>> >> >>> >> I'm planning on implementing the table listing using pyqt this
>> >> >>> >> week. I
>> >> >>> >> was a
>> >> >>> >> little delayed by my master's application.
>> >> >>> >>
>> >> >>> >> The idea in the plugin is simply find the QGIS's conections
>> >> >>> >> available,
>> >> >>> >> list
>> >> >>> >> the raster tables inside postgis and pass the right arguments to
>> >> >>> >> the
>> >> >>> >> gdal
>> >> >>> >> driver.
>> >> >>> >>
>> >> >>> >> At the moment I haven't found any gdal 1.7 windows build with
>> >> >>> >> QGIS.
>> >> >>> >> GDAL 1.7
>> >> >>> >> introduces wktraster. The driver conects to postgis raster and
>> >> >>> >> read
>> >> >>> >> it
>> >> >>> >> as a
>> >> >>> >> binary. It's still VERY unstable and gdal version 1.8 seems to
>> >> >>> >> be
>> >> >>> >> greatly
>> >> >>> >> improved.
>> >> >>> >> So what a windows user need to get the plugin to work is a
>> >> >>> >> (still
>> >> >>> >> not
>> >> >>> >> found)
>> >> >>> >> qgis compiled against gdal 1.7.
>> >> >>> >> You can compile your's from source if needed.
>> >> >>> >>
>> >> >>> >> So, as far as qgis to wktraster, with the plugin qgis reads the
>> >> >>> >> wktraster as
>> >> >>> >> a regular raster. Just for show. If you did some kind of
>> >> >>> >> processing
>> >> >>> >> and
>> >> >>> >> populated a new raster table, qgis is going to read that result
>> >> >>> >> too.
>> >> >>> >> The
>> >> >>> >> plugin is not intended (at the moment at least) to raster
>> >> >>> >> processing
>> >> >>> >> inside
>> >> >>> >> postgis. It just loads the table to the screen.
>> >> >>> >>
>> >> >>> >> In the future, with a more stable wktraster probably someone (or
>> >> >>> >> me)
>> >> >>> >> is
>> >> >>> >> going to write a set of wktraster's tools as a plugin, but for
>> >> >>> >> the
>> >> >>> >> moment it
>> >> >>> >> should be run as sql. I advise postgis manager's to the task.
>> >> >>> >>
>> >> >>> >> Best regards,
>> >> >>> >>
>> >> >>> >>
>> >> >>> >> 2010/11/29 Stefan Keller <... at gmail.com>
>> >> >>> >>>
>> >> >>> >>> Hi,
>> >> >>> >>>
>> >> >>> >>> There are new versions around of "PostGIS Raster"
>> >> >>> >>> (renamed from formerly known "PostGIS WKT Raster").
>> >> >>> >>>
>> >> >>> >>> What's the status of your "WKTRaster Plugin 0.1"?
>> >> >>> >>> I assume it's rendering the raster values (e.g. from
>> >> >>> >>> ST_AsBinary)
>> >> >>> >>> -
>> >> >>> >>> not the polygons/geomvals (from ST_DumpAsPolygons), right?
>> >> >>> >>> Is there a chance to get it running on Windows too?
>> >> >>> >>> Are there other plugins?
>> >> >>> >>>
>> >> >>> >>> Yours, S.
>> >> >>> > _______________________________________________
>> >> >>> > postgis-users mailing list
>> >> >>> > postgis-users at postgis.refractions.net
>> >> >>> > http://postgis.refractions.net/mailman/listinfo/postgis-users
>> >> >>> >
>> >> >>
>> >> >>
>> >> >>
>> >> >> --
>> >> >> Mauricio de Paulo
>> >> >> Engenheiro Cartografo
>> >> >>
>> >> >
>> >> >
>> >> >
>> >> > --
>> >> > Mauricio de Paulo
>> >> > Engenheiro Cartografo
>> >> >
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> Jorge Arévalo
>> >> Internet & Mobilty Division, DEIMOS
>> >> jorge.arevalo at deimos-space.com
>> >> http://mobility.grupodeimos.com/
>> >> http://gis4free.wordpress.com
>> >
>> >
>> >
>> > --
>> > Mauricio de Paulo
>> > Engenheiro Cartografo
>> >
>> >
>
>
>
> --
> Mauricio de Paulo
> Engenheiro Cartografo
>
>