[Geoserver-users] Poor quality rendering of layers in Layer Group

GeoServer GeoServer User
1

Hi all,

I have my WMS service and raster layers configured use bilinear resampling. While these layers look perfect on their own, when added to a layer group, GeoServer seems to fall back to nearest neighbour resampling making the image quality worse. I’ve noticed this behaviour whenever there’s more than one layer in a layer group as a layer group containing only a single a single layer appears fine.

I’ve found the issue has already been reported on the mailing list by someone else as affecting GeoServer v2.1. I’m using 2.6.2 so obviously the issue has yet to be addressed. The existing issue can be found here: http://sourceforge.net/p/geoserver/mailman/message/27750315/

Here is a link which includes an example of a layer group with a single layer (same as viewing the layer on it’s own) and another showing the layer group with multiple layers: https://drive.google.com/folderview?id=0B0QYHTaybWU_fjF5SEtCSDZvOU1PRzVCb3J1dFBiWUloYnJCUDRua201ZGZweGtrTnUtb3c&usp=sharing

The issue linked above mentioned that in GeoServer 2.1 the raster rendering code paths were split; one is server in image server mode, and the other in map server mode, which is likely the cause of this.

This really needs to be fixed.

Cheers,
Tom

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2

On Mon, May 4, 2015 at 6:49 AM, Tom Wardrop <TomW@anonymised.com> wrote:

  Hi all,

I have my WMS service and raster layers configured use bilinear
resampling. While these layers look perfect on their own, when added to a
layer group, GeoServer seems to fall back to nearest neighbour resampling
making the image quality worse. I’ve noticed this behaviour whenever
there’s more than one layer in a layer group as a layer group containing
only a single a single layer appears fine.

I’ve found the issue has already been reported on the mailing list by
someone else as affecting GeoServer v2.1. I’m using 2.6.2 so obviously the
issue has yet to be addressed. The existing issue can be found here:
http://sourceforge.net/p/geoserver/mailman/message/27750315/

Here is a link which includes an example of a layer group with a single
layer (same as viewing the layer on it’s own) and another showing the layer
group with multiple layers:
https://drive.google.com/folderview?id=0B0QYHTaybWU_fjF5SEtCSDZvOU1PRzVCb3J1dFBiWUloYnJCUDRua201ZGZweGtrTnUtb3c&usp=sharing

  The issue linked above mentioned that in GeoServer 2.1 the raster
rendering code paths were split; one is server in image server mode, and
the other in map server mode, which is likely the cause of this.

I see the thread, but could not find a ticket in the bug tracker. There are
too many discussions, we just lose track
of them, could you open a report in the bug tracker instead?
https://osgeo-org.atlassian.net/projects/GEOS

  This really needs to be fixed.

As an open source project, features and fixes are done either when there is
funding directed to a specific topic (working hours jobs)
or when someone decides they are more important than their spare time
(spare time jobs). Everybody is invited to contribute,
and indeed many do, we have like 60 contributors over a year, against a
core team of 5-10 direct committers.

You seem to be motivated, do you have time and skill?
Instructions for contribute here:
https://github.com/geoserver/geoserver/blob/master/CONTRIBUTING.md
Or if anybody else here wants to help, and has skill related to rendering,
this would be a great occasion to
give back to the project, too.

Cheers
Andrea

--

GeoServer Professional Services from the experts! Visit
http://goo.gl/NWWaa2 for more information.

Ing. Andrea Aime
@geowolf
Technical Lead

GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39 339 8844549

http://www.geo-solutions.it
http://twitter.com/geosolutions_it

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3

Hey Andrea,

I’ve submitted a bug report for this: https://osgeo-org.atlassian.net/browse/GEOS-7012

I’ve spent quite some time looking through the source code, but having written very little in Java (let alone Spring, etc), and not having any kind of IDE or environment setup, it’s been a challenge getting any kind of insight into what’s happening. It’s likely that someone more familiar with the source code would be able to identify the root cause pretty quickly.

Cheers,

Tom

···

On Mon, May 4, 2015 at 6:49 AM, Tom Wardrop <TomW@anonymised.com> wrote:

Hi all,

I have my WMS service and raster layers configured use bilinear resampling. While these layers look perfect on their own, when added to a layer group, GeoServer seems to fall back to nearest neighbour resampling making the image quality worse. I’ve noticed this behaviour whenever there’s more than one layer in a layer group as a layer group containing only a single a single layer appears fine.

I’ve found the issue has already been reported on the mailing list by someone else as affecting GeoServer v2.1. I’m using 2.6.2 so obviously the issue has yet to be addressed. The existing issue can be found here: http://sourceforge.net/p/geoserver/mailman/message/27750315/

Here is a link which includes an example of a layer group with a single layer (same as viewing the layer on it’s own) and another showing the layer group with multiple layers: https://drive.google.com/folderview?id=0B0QYHTaybWU_fjF5SEtCSDZvOU1PRzVCb3J1dFBiWUloYnJCUDRua201ZGZweGtrTnUtb3c&usp=sharing

The issue linked above mentioned that in GeoServer 2.1 the raster rendering code paths were split; one is server in image server mode, and the other in map server mode, which is likely the cause of this.

I see the thread, but could not find a ticket in the bug tracker. There are too many discussions, we just lose track
of them, could you open a report in the bug tracker instead?
https://osgeo-org.atlassian.net/projects/GEOS

This really needs to be fixed.

As an open source project, features and fixes are done either when there is funding directed to a specific topic (working hours jobs)
or when someone decides they are more important than their spare time (spare time jobs). Everybody is invited to contribute,
and indeed many do, we have like 60 contributors over a year, against a core team of 5-10 direct committers.

You seem to be motivated, do you have time and skill?

Instructions for contribute here: https://github.com/geoserver/geoserver/blob/master/CONTRIBUTING.md

Or if anybody else here wants to help, and has skill related to rendering, this would be a great occasion to
give back to the project, too.

Cheers
Andrea

–

==

GeoServer Professional Services from the experts! Visit
http://goo.gl/NWWaa2 for more information.

==

Ing. Andrea Aime

@geowolf
Technical Lead

GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39 339 8844549

http://www.geo-solutions.it
http://twitter.com/geosolutions_it

AVVERTENZE AI SENSI DEL D.Lgs. 196/2003

Le informazioni contenute in questo messaggio di posta elettronica e/o nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il loro utilizzo è consentito esclusivamente al destinatario del messaggio, per le finalità indicate nel messaggio stesso. Qualora riceviate questo messaggio senza esserne il destinatario, Vi preghiamo cortesemente di darcene notizia via e-mail e di procedere alla distruzione del messaggio stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso, divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od utilizzarlo per finalità diverse, costituisce comportamento contrario ai principi dettati dal D.Lgs. 196/2003.

The information in this message and/or attachments, is intended solely for the attention and use of the named addressee(s) and may be confidential or proprietary in nature or covered by the provisions of privacy act (Legislative Decree June, 30 2003, no.196 - Italy’s New Data Protection Code).Any use not in accord with its purpose, any disclosure, reproduction, copying, distribution, or either dissemination, either whole or partial, is strictly forbidden except previous formal approval of the named addressee(s). If you are not the intended recipient, please contact immediately the sender by telephone, fax or e-mail and delete the information in this message that has been received in error. The sender does not give any warranty or accept liability as the content, accuracy or completeness of sent messages and accepts no responsibility for changes made after they were sent or for other risks which arise as a result of e-mail transmission, viruses, etc.