[Qgis-developer] Integrating OSSIM with QGIS

[Peter Borissow]

Hi Marco-
    The new provider is based on ossim which at its core has relatively few dependencies (libtiff, geotiff, jpeg, openthreads, etc). Ming will push out the code next week after we shake a couple more things out. The band statistics is a real killer right now. We could really use your advice on that. It requires changes to one of the the base classes.

As for (1), I think the simplest thing to do is to have a global preference/getting to select an image provider. This would be an interim solution while we flesh out the ossim provider.

BTW, Ming figured out (5) last night - simple one liner. 

In summary, we're still exploring (2) Band Statistics and (4) method for passing in definitions for image chains. Any thoughts/suggestions would be greatly appreciated!


Best Regards,
Peter


________________________________________
From: Marco Hugentobler [marco.hugentobler at sourcepole.ch]
Sent: Thursday, June 09, 2011 2:56 AM
To: qgis-developer at lists.osgeo.org; qgis-ossim at lists.sourceforge.net
Cc: Mingjie Su; Peter Borissow; Harsh Govind
Subject: Re: [Qgis-developer] Integrating OSSIM with QGIS

Hi Ming

This sounds interesting. What dependencies on external libraries does the
provider have?

> (5) Can we post our ossim image provider to your svn for others to play
> with?

QGIS switched to git in the meantime. You could clone the QGIS repository
(git at github.com:qgis/Quantum-GIS.git) and upload the changes to the cloned
repo. Or just provide a patch against current master branch.

> (1) Is there a way for users to specify which provider to use? It looks
> like QGIS is hard coded to use the GDAL provider.

This needs changes in the GUI. If it is only about file based datasources, it
is a possibility to add a combo box to the 'add rasterlayer' dialog.

If database / web services should also be accessed, it might be necessary to
add a new dialog.

Regards,
Marco

Am Mittwoch, 8. Juni 2011, 21.21:05 schrieb Mingjie Su:
> All-
>    We are making some good progress on the ossim image provider
> (qgsossimprovider.cpp). Couple questions:
>
> (1) Is there a way for users to specify which provider to use? It looks
> like QGIS is hard coded to use the GDAL provider.
>
> (2) Band statistics. QGIS is pretty inefficient when it comes to computing
> band statistics. Its looping through all the pixels multiple times (once
> for each band) to populate the viewport. For RGB data for example, its
> looping through the data 3 times. In OSSIM, we can provide the band
> statistics for you so you don't have to scan the data. This will speed
> things up dramatically. BTW, this is true for both the GDAL and OSSIM
> providers.
>
> (3) Black pixels (0,0,0 RGB) are being flipped to transparent. Is there a
> way to override this behavior programatically?
>
> (4) In OSSIM we have a concept of image chains and connectable objects. You
> can wire up all kinds of filters and equations into a workflow to create
> an output image. The image chain can be represented using an array of key
> value pairs. Does the provider interface provide a mechanism for passing
> this type of information?
>
> (5) Can we post our ossim image provider to your svn for others to play
> with?
>
>
> Thanks,
> Ming
>
>
>
> -----Original Message-----
> From: Peter Borissow
> Sent: Wednesday, May 25, 2011 4:08 PM
> To: Tim Sutton; Pirmin Kalberer
> Cc: qgis-developer at lists.osgeo.org; qgis-ossim at lists.sourceforge.net;
> Mingjie Su; Harsh Govind Subject: RE: [Qgis-developer] Integrating OSSIM
> with QGIS
>
> Hi Tim-
>    We are playing with 1.6. We'll download the 1.7 branch right away. I
> agree, use of gdal should be abstracted away into a gdal provider. Sounds
> like we would create an OSSIM provider.
>
> And yes, we want to create/execute OSSIM image chains directly in QGIS!
>
> Thanks,
> Peter
>
>
>
> -----Original Message-----
> From: Tim Sutton [mailto:lists at linfiniti.com]
> Sent: Wednesday, May 25, 2011 4:03 PM
> To: Pirmin Kalberer
> Cc: qgis-developer at lists.osgeo.org; Peter Borissow;
> qgis-ossim at lists.sourceforge.net; Mingjie Su; Harsh Govind Subject: Re:
> [Qgis-developer] Integrating OSSIM with QGIS
>
> Hi Peter
>
> 8<-------------------snip----------------------
>
> >> > We started our investigation late last week. We have a debug version
> >> > of QGIS up and running in Visual Studio 10 (64 bit) using QT 4.7.3. We
> >> > have since discovered how integral GDAL is to QGIS. Undaunted, we
> >> > added a some temporary hacks to bypass GDAL and we're now getting
> >> > images to display via OSSIM! For us, this is a huge first step and we
> >> > are seriously considering pressing ahead.
>
> What version are you building against? Since the 1.7 branch and in
> current master branch, Radim Blazek has done a great overhaul to cater
> for proper raster providers. That means you should not find QGIS is
> heavily intertwined with GDAL - the use of gdal should be abstracted
> away into the gdal provider, and you should be able to implement ossim
> raster support as a clean separate provider.
>
> I would also really love to see OSSIM support in QGIS (and maybe some
> of those nice processing chains making their way into QGIS :-).
>
> Regards
>
> Tim
>
> 8<-------------------snip----------------------


--
Dr. Marco Hugentobler
Sourcepole -  Linux & Open Source Solutions
Churerstrasse 22, CH-8808 Pfäffikon SZ, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee