Hello,
We have set of rasters layers for WMS. If a large boundary request is made
for a png at base level with a large image size, such as height and width of
2000 pixels the image is perfect quality, very crisp as expected. However
if the exact same bounds are used and the height and width are reduced to
say 500 pixels, the png returned is of very low quality (blurry and
pixelated). We have attempted all resampling methods, bilinear is the best
but still very blurry. Are there any settings in geoserver wms to better
improve the quality of images when reductions in size are made?
Our current work around is to request the image at full size and then
externally resize the image using imagemagick, but we would like to remove
this extra step if we could.
Thanks,
Brad
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Additional info: This effect occurs only when transforming the image to conic
or other rotated projections. Example: the source data is in epsg:3395 ..
we can make any wms request in that same projection and reduce the size via
the request and the image is of high quality. However if we make the
request and reproject the results to a conic projection we are seeing the
degradation of the image only when resizing the image in the same request.
No reprojection at full size = perfect image
No reprojection at reduced file size = perfect image
Reprojection to conic (in this case espg:102009) at full size = perfect
image
Reprojection to conic (in this case espg:102009) at reduced file size = very
poor/blurry image
Any ideas on what may be causing this or a workaround would be greatly
appreciated.
Thanks!
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On Tue, Apr 15, 2014 at 7:20 PM, bhecox <bhecox@anonymised.com> wrote:
Additional info: This effect occurs only when transforming the image to
conic
or other rotated projections. Example: the source data is in epsg:3395 ..
we can make any wms request in that same projection and reduce the size via
the request and the image is of high quality. However if we make the
request and reproject the results to a conic projection we are seeing the
degradation of the image only when resizing the image in the same request.
No reprojection at full size = perfect image
No reprojection at reduced file size = perfect image
Reprojection to conic (in this case espg:102009) at full size = perfect
image
Reprojection to conic (in this case espg:102009) at reduced file size =
very
poor/blurry image
Hmm.. not sure off the top of my head, it may be that the target area in
conic projection
is very different (in terms of square meters) from the original one, due to
the projection
stretching the data.
Which version of GeoServer are you using?
Cheers
Andrea
--
Meet us at GEO Business 2014! in London! Visit http://goo.gl/fES3aK
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
-------------------------------------------------------
Thanks for the reply Andrea. We are using geoserver 2.5.0. The part we find most confusing is if we make the same request in the same projection with a width and height of a larger value (2000 pixels or so) it looks perfect. It is only when we make the request with a smaller width and height (500 pixels) in this projection that we see the image quality drop dramatically. We will play with some other similar projections to see if that helps.
Thanks again,
Brad
···
On Tue, Apr 15, 2014 at 7:20 PM, bhecox <bhecox@anonymised.com.> wrote:
Additional info: This effect occurs only when transforming the image to conic
or other rotated projections. Example: the source data is in epsg:3395 …
we can make any wms request in that same projection and reduce the size via
the request and the image is of high quality. However if we make the
request and reproject the results to a conic projection we are seeing the
degradation of the image only when resizing the image in the same request.
No reprojection at full size = perfect image
No reprojection at reduced file size = perfect image
Reprojection to conic (in this case espg:102009) at full size = perfect
image
Reprojection to conic (in this case espg:102009) at reduced file size = very
poor/blurry image
Hmm… not sure off the top of my head, it may be that the target area in conic projection
is very different (in terms of square meters) from the original one, due to the projection
stretching the data.
Which version of GeoServer are you using?
Cheers
Andrea
–
==
Meet us at GEO Business 2014! in London! Visit http://goo.gl/fES3aK
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