Gridset question

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Gridset question

GeoServer - User mailing list

Hi,

 

Does anyone know why my base mapping is moving when I preview the cached content in British National Grid (EPSG:27700)?

 

Please see the attached screenshot.

 

It doesn’t do this in web Mercator projection. If you try to zoom in using this gridset the you end up in a completely different point (because the map centre is shifting) whilst if you scroll in on other projections the map centre remains constant.

 

It seems to have a minimal shift if I use the WMTS in QGIS but if I use it in MapInfo Confirm then the shift is more pronounced.

 

Best Regards,

 

Paul Wittle

GIS Developer

Insight, Intelligence & Performance

 

County Hall

Dorchester

Dorset. DT1 1XJ

Tel: 01305 228473

E mail: [hidden email]

 

"This e-mail is intended for the named addressee(s) only and may contain information about individuals or other sensitive information and should be handled accordingly. Unless you are the named addressee (or authorised to receive it for the addressee) you may not copy or use it, or disclose it to anyone else. If you have received this email in error, kindly disregard the content of the message and notify the sender immediately. Please be aware that all email may be subject to recording and/or monitoring in accordance with relevant legislation."

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Please make sure you read the following two resources before posting to this list:
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If you want to request a feature or an improvement, also see this: https://github.com/geoserver/geoserver/wiki/Successfully-requesting-and-integrating-new-features-and-improvements-in-GeoServer


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Re: Gridset question

Phil Scadden

This rings some distant bells, though not with that particular EPSG (I’m in antipodes). I have vague memory of needing to set a tile origin somewhere. First step would be to isolate whether your issue is with geoserver or the browser client. (my memories of this are with openlayers but I switched to leaflet some time ago).

Can you look at the getmap request that browser is issuing and see whether the image being sent matches the bbox being requested. If so, then geoserver is off the hook and the problem is with the tileset management in the browser client. If it doesn’t match, then problem is with geoserver. You say “cached content” – are you explicitly connected to a GWC cache or tileset, or is this from integrated GWC where you have seeded tiles? If you turn caching off, does the problem persist?

 

From: Paul Wittle via Geoserver-users <[hidden email]>
Sent: Friday, 8 February 2019 01:54
To: '[hidden email]' <[hidden email]>
Subject: [Geoserver-users] Gridset question

 

Hi,

 

Does anyone know why my base mapping is moving when I preview the cached content in British National Grid (EPSG:27700)?

 

Please see the attached screenshot.

 

It doesn’t do this in web Mercator projection. If you try to zoom in using this gridset the you end up in a completely different point (because the map centre is shifting) whilst if you scroll in on other projections the map centre remains constant.

 

It seems to have a minimal shift if I use the WMTS in QGIS but if I use it in MapInfo Confirm then the shift is more pronounced.

 

Best Regards,

 

Paul Wittle

GIS Developer

Insight, Intelligence & Performance

 

County Hall

Dorchester

Dorset. DT1 1XJ

Tel: 01305 228473

E mail: [hidden email]

 

"This e-mail is intended for the named addressee(s) only and may contain information about individuals or other sensitive information and should be handled accordingly. Unless you are the named addressee (or authorised to receive it for the addressee) you may not copy or use it, or disclose it to anyone else. If you have received this email in error, kindly disregard the content of the message and notify the sender immediately. Please be aware that all email may be subject to recording and/or monitoring in accordance with relevant legislation."

Notice: This email and any attachments are confidential and may not be used, published or redistributed without the prior written consent of the Institute of Geological and Nuclear Sciences Limited (GNS Science). If received in error please destroy and immediately notify GNS Science. Do not copy or disclose the contents.


_______________________________________________
Geoserver-users mailing list

Please make sure you read the following two resources before posting to this list:
- Earning your support instead of buying it, but Ian Turton: http://www.ianturton.com/talks/foss4g.html#/
- The GeoServer user list posting guidelines: http://geoserver.org/comm/userlist-guidelines.html

If you want to request a feature or an improvement, also see this: https://github.com/geoserver/geoserver/wiki/Successfully-requesting-and-integrating-new-features-and-improvements-in-GeoServer


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Re: Gridset question

GeoServer - User mailing list
In reply to this post by GeoServer - User mailing list
Hi,

Unfortunately the question relates directly to using the WMTS service in MapExtreme which is developed by Pitney Bowes (who also own MapInfo and Confirm).

After investigating I have pretty much decided it is more a client issue as so far as I can tell the bounding box of the layer is changing at each zoom level. The top-left coordinates are moving so I can't see what else could be causing it. I assume this is why it is jumping in the GeoServer OpenLayers preview as well as it may be configured to use the top-left anchor.

My working theory is that MapExtreme is assuming that the bounding box is the same at all levels rather than recalculating it at each zoom level based on the information provided by the WMTS getCapabilities statement. Might be completely wrong but I suspect it may be a development request to PB if I'm correct. In fairness; the shift is only a few meters at the detailed level but it is still significant if you are trying to be accurate; our gully locations appear to be moving around on the road / pavement as a result.

If you have an interest; I'm not sure why you would voluntarily research MapExtreme; but if you do, the layer bounding box is set to 0,0,700000,1300000 but this is the bounding box as calculated by MapInfo 17 (also has the same behaviour) and MapExtreme:
CoordSys Earth Projection 8, 79, "m", -2, 49, 0.9996012717, 400000, -100000 Bounds (4.53547443948e-11, 0.313325276111) (760926.343337, 1521853)

You can see that the y coordinate is expanded to 1,521,853 which is a around 200,000 meters away from the bounding box of the data. My understanding is that this is because the gridset has been expanded for mathematical reasons but that the data should still be in the right place.

Anyway, I'll stop there as it is unlikely to be a GeoServer issue; more likely a MapExtreme or GWC issue.
If anyone does have a work around then I'd love to hear it though.
Cheers,
Paul

-----------------------------

Message: 3
Date: Thu, 7 Feb 2019 20:07:44 +0000
From: Phil Scadden <[hidden email]>
To: "[hidden email]"
<[hidden email]>
Subject: Re: [Geoserver-users] Gridset question
Message-ID:
<[hidden email]>

Content-Type: text/plain; charset="us-ascii"

This rings some distant bells, though not with that particular EPSG (I'm in antipodes). I have vague memory of needing to set a tile origin somewhere. First step would be to isolate whether your issue is with geoserver or the browser client. (my memories of this are with openlayers but I switched to leaflet some time ago).
Can you look at the getmap request that browser is issuing and see whether the image being sent matches the bbox being requested. If so, then geoserver is off the hook and the problem is with the tileset management in the browser client. If it doesn't match, then problem is with geoserver. You say "cached content" - are you explicitly connected to a GWC cache or tileset, or is this from integrated GWC where you have seeded tiles? If you turn caching off, does the problem persist?

From: Paul Wittle via Geoserver-users <[hidden email]>
Sent: Friday, 8 February 2019 01:54
To: '[hidden email]' <[hidden email]>
Subject: [Geoserver-users] Gridset question

Hi,

Does anyone know why my base mapping is moving when I preview the cached content in British National Grid (EPSG:27700)?

Please see the attached screenshot.

It doesn't do this in web Mercator projection. If you try to zoom in using this gridset the you end up in a completely different point (because the map centre is shifting) whilst if you scroll in on other projections the map centre remains constant.

It seems to have a minimal shift if I use the WMTS in QGIS but if I use it in MapInfo Confirm then the shift is more pronounced.

Best Regards,

Paul Wittle
GIS Developer
Insight, Intelligence & Performance

County Hall
Dorchester
Dorset. DT1 1XJ
Tel: 01305 228473
E mail: [hidden email]<mailto:[hidden email]>

"This e-mail is intended for the named addressee(s) only and may contain information about individuals or other sensitive information and should be handled accordingly. Unless you are the named addressee (or authorised to receive it for the addressee) you may not copy or use it, or disclose it to anyone else. If you have received this email in error, kindly disregard the content of the message and notify the sender immediately. Please be aware that all email may be subject to recording and/or monitoring in accordance with relevant legislation."
Notice: This email and any attachments are confidential and may not be used, published or redistributed without the prior written consent of the Institute of Geological and Nuclear Sciences Limited (GNS Science). If received in error please destroy and immediately notify GNS Science. Do not copy or disclose the contents.
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"This e-mail is intended for the named addressee(s) only and may contain information about individuals or other sensitive information and should be handled accordingly. Unless you are the named addressee (or authorised to receive it for the addressee) you may not copy or use it, or disclose it to anyone else. If you have received this email in error, kindly disregard the content of the message and notify the sender immediately. Please be aware that all email may be subject to recording and/or monitoring in accordance with relevant legislation."


_______________________________________________
Geoserver-users mailing list

Please make sure you read the following two resources before posting to this list:
- Earning your support instead of buying it, but Ian Turton: http://www.ianturton.com/talks/foss4g.html#/
- The GeoServer user list posting guidelines: http://geoserver.org/comm/userlist-guidelines.html

If you want to request a feature or an improvement, also see this: https://github.com/geoserver/geoserver/wiki/Successfully-requesting-and-integrating-new-features-and-improvements-in-GeoServer


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