Hi,
We are finding that segments of our network data from the database are being excluded from the images generated by the WMS. The extent of missing data is different in different zoom scales. The attached images highlights the same. The image shows two WMS services (one is yellow and other is black). There layers are published from a oracle spatial table using GeoServer. GeoHUB server applies some clauses to filter out some data from WMS. It will be fare to say these layers arebased on a view from GeoServer on top of oracle table.
Currently we have our OpenLayers application calling network data overlays as a set of tiled images 256 x 256 pixels. In some cases, parts of features close to the edge of each tile are not being rendered.
If I publish the oracle table without creating a view and without creating a filter in GeoServer the gaps in images do not appear.
Can you suggest a reason why this may be happening? This behaviour seems somewhat inconsistent, it does not happen for all features intersecting the tile boundaries, but seemingly on every map refresh there is at least one patch of missing data. I would be very grateful for any inputs on this problem and also our other observation that features seem to disappear altogether when we zoom in very close.
Many thanks and best regards
Regards,
Manish Barapatre | BT TSO | P&B-PIPeR, GeoHUB Design
PP5, 2nd Floor, Orion, Adastral Park, Ipswich (UK)
Office: 01473 650516
Mobile : 07526571760
gaps in wms images.zip (127 KB)
On Wed, Feb 20, 2013 at 3:49 PM, <manish.barapatre@anonymised.com> wrote:
Hi,
We are finding that segments of our network data from the database are being excluded from the images generated by the WMS. The extent of missing data is different in different zoom scales. The attached images highlights the same. The image shows two WMS services (one is yellow and other is black). There layers are published from a oracle spatial table using GeoServer. GeoHUB server applies some clauses to filter out some data from WMS. It will be fare to say these layers arebased on a view from GeoServer on top of oracle table.
Currently we have our OpenLayers application calling network data overlays as a set of tiled images 256 x 256 pixels. In some cases, parts of features close to the edge of each tile are not being rendered.
If I publish the oracle table without creating a view and without creating a filter in GeoServer the gaps in images do not appear.
Can you suggest a reason why this may be happening? This behaviour seems somewhat inconsistent, it does not happen for all features intersecting the tile boundaries, but seemingly on every map refresh there is at least one patch of missing data. I would be very grateful for any inputs on this problem and also our other observation that features seem to disappear altogether when we zoom in very close.
By looking at your screenshots it seems every tile has some slight misalignment to the others, and some
indeed miss data.
For the misalignments, it seems your OL client is not properly setup, or the application sitting in the middle
between OpenLayers and GeoServer is changing the bounds.
For the missing data… I don’t know.
If you look at the data in the GeoServer own preview, and switch it to tiled mode, do you have any missing
data or mis-alignments?
If not, then the issues are likely caused either by your client or the application sitting in the middle
Cheers
Andrea
–
Ing. Andrea Aime
@geowolf
Technical Lead
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