[Geoserver-users] Reduce Geometry size in GetFeatureInfo responses?

GeoServer GeoServer User
1

We’re looking for ways to improve performance of Identify operations in a web map client (using OpenLayers). We are seeing poor performance due to the network latency of retrieving large GetFeatureInfo reponses. Is there any way to reduce the size of geometries returned in GetFeatureInfo responses?

In order of decreasing preference, things that might work for us include:

  1. simplify the geometry
  2. provide only the bounding box rather than full geometry
  3. eliminate the geometry entirely

Does the WMS vendor parameter propertyName [1] allow removing the geometry from the response? In any case this isn’t ideal for us, because we’d prefer to not have to specify the required properties explicitly.

The #2 option of returning only BBOX would be ideal - is that possible?

2

I should add that it’s probably not feasible to use FreeMarker templates, since we have a lot of layers defined, and in some cases we don’t have the ability to modify the server configuration. Also, we also want to be able to retrieve the geometry via GetFeatureInfo in some situations. Ideally there would be some kind of query parameter that could be added to control how the geometry is returned in the response.

···

On Wed, Jun 10, 2015 at 10:41 AM, Martin Davis <mtnclimb@anonymised.com> wrote:

We’re looking for ways to improve performance of Identify operations in a web map client (using OpenLayers). We are seeing poor performance due to the network latency of retrieving large GetFeatureInfo reponses. Is there any way to reduce the size of geometries returned in GetFeatureInfo responses?

In order of decreasing preference, things that might work for us include:

  1. simplify the geometry
  2. provide only the bounding box rather than full geometry
  3. eliminate the geometry entirely

Does the WMS vendor parameter propertyName [1] allow removing the geometry from the response? In any case this isn’t ideal for us, because we’d prefer to not have to specify the required properties explicitly.

The #2 option of returning only BBOX would be ideal - is that possible?

3

On Wed, Jun 10, 2015 at 7:41 PM, Martin Davis <mtnclimb@anonymised.com> wrote:

We're looking for ways to improve performance of Identify operations in a
web map client (using OpenLayers). We are seeing poor performance due to
the network latency of retrieving large GetFeatureInfo reponses. Is there
any way to reduce the size of geometries returned in GetFeatureInfo
responses?

In order of decreasing preference, things that might work for us include:

1. simplify the geometry
2. provide only the bounding box rather than full geometry
3. eliminate the geometry entirely

Does the WMS vendor parameter propertyName [1] allow removing the geometry
from the response? In any case this isn't ideal for us, because we'd
prefer to not have to specify the required properties explicitly.

Yeah, you can get whatever property you want, but you have to list
explicitly the ones you require

The #2 option of returning only BBOX would be ideal - is that possible?

Not without changing the code, I guess you could roll a new vendor option,
e.g., &geometry=none|bbox|standard
Simplifying would require yet another param to specify how much to simplify
it.

Cheers
Andrea

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4

Thanks. That’s pretty much what I expected to hear.

The vendor option idea sounds good, particularly for the none|bbox options.

Agreed that the simplify option would also require a tolerance value. On further thought I’m not sure this would provide an effect that is all that useful, since it’s so tied to view map scale.

We’ll have to weigh the cost of a code enhancement versus the pain of other options…

···

On Wed, Jun 10, 2015 at 10:57 AM, Andrea Aime <andrea.aime@anonymised.com> wrote:

On Wed, Jun 10, 2015 at 7:41 PM, Martin Davis <mtnclimb@anonymised.com> wrote:

We’re looking for ways to improve performance of Identify operations in a web map client (using OpenLayers). We are seeing poor performance due to the network latency of retrieving large GetFeatureInfo reponses. Is there any way to reduce the size of geometries returned in GetFeatureInfo responses?

In order of decreasing preference, things that might work for us include:

  1. simplify the geometry
  2. provide only the bounding box rather than full geometry
  3. eliminate the geometry entirely

Does the WMS vendor parameter propertyName [1] allow removing the geometry from the response? In any case this isn’t ideal for us, because we’d prefer to not have to specify the required properties explicitly.

Yeah, you can get whatever property you want, but you have to list explicitly the ones you require

The #2 option of returning only BBOX would be ideal - is that possible?

Not without changing the code, I guess you could roll a new vendor option, e.g., &geometry=none|bbox|standard
Simplifying would require yet another param to specify how much to simplify it.

5

Hi,

I would add one more

  1. Reduce the precision of coordinates

-Jukka Rahkonen-

···

Martin Davis wrote:

We’re looking for ways to improve performance of Identify operations in a web map client (using OpenLayers). We are seeing poor performance due to the network latency of retrieving large GetFeatureInfo reponses. Is there any way to reduce the size of geometries returned in GetFeatureInfo responses?

In order of decreasing preference, things that might work for us include:

  1. simplify the geometry
  2. provide only the bounding box rather than full geometry
  3. eliminate the geometry entirely

Does the WMS vendor parameter propertyName [1] allow removing the geometry from the response? In any case this isn’t ideal for us, because we’d prefer to not have to specify the required properties explicitly.

The #2 option of returning only BBOX would be ideal - is that possible?

6

We did consider this option as well, but we don’t think it will move the needle enough on download size and processing time. Problematic datasets have features with over 10K coordinates. Even if we dropped half the coordinate digits, this would still only reduce the response size to 50%. That’s better, but not down to the “< 5%” improvement that the NONE or BBOX strategy would provide.

···

On Wed, Jun 10, 2015 at 2:09 PM, Rahkonen Jukka (MML) <jukka.rahkonen@anonymised.com> wrote:

Hi,

I would add one more

  1. Reduce the precision of coordinates

-Jukka Rahkonen-

Martin Davis wrote:

We’re looking for ways to improve performance of Identify operations in a web map client (using OpenLayers). We are seeing poor performance due to the network latency of retrieving large GetFeatureInfo reponses. Is there any way to reduce the size of geometries returned in GetFeatureInfo responses?

In order of decreasing preference, things that might work for us include:

  1. simplify the geometry
  2. provide only the bounding box rather than full geometry
  3. eliminate the geometry entirely

Does the WMS vendor parameter propertyName [1] allow removing the geometry from the response? In any case this isn’t ideal for us, because we’d prefer to not have to specify the required properties explicitly.

The #2 option of returning only BBOX would be ideal - is that possible?

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7

I would say take a leaf from ESRI REST services and add ReturnGeometry=true/false to getFeatureInfo would be a good extension to the WMS format. If you dont really need to execute against multiple layers, then consider using WFS getFeature instead where you can specify propertynames. ( My maps have the concept of "active layer" for use in all searching, hover controls etc.)

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8

I would say take a leaf from ESRI REST services and add
ReturnGeometry=true/false to getFeatureInfo would be a good extension to
the WMS format. If you dont really need to execute against multiple
layers, then consider using WFS getFeature instead where you can specify
propertynames. ( My maps have the concept of "active layer" for use in
all searching, hover controls etc.)

Actually, I see that propertynames (exclude the shape from list) is a geoserver vendor option for single layer getFeatureInfo. If using OL, you would need to make sure that is in the options parameter for the control, rather than using the propertyNames parameter of the getFeatureInfo control (which filters the fields AFTER the call). returnGeometry=true/false would be a better extension however because it would with multiple layers.

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9

All good advice, but unfortunately not so easy to take advantage of in our environment.

We allow all visible layers to be queried. This is why we prefer GetFeatureInfo to WFS, since it’s sensitive to scale limits.

The propertynames option is one way to do this, but we have hundreds of layers, so this would involve a large amount of client-side configuration. And that configuration is brittle - we don’t totally control the map servers, and if a property name changes then the request will fail (I think…)

A new vendor option of “geometry=none|bbox” would work well for us, since it offers maximum flexibility for minimum configuration. ESRI sometimes has good ideas… 8^)

···

On Wed, Jun 10, 2015 at 2:44 PM, Phil Scadden <p.scadden@anonymised.com> wrote:

I would say take a leaf from ESRI REST services and add
ReturnGeometry=true/false to getFeatureInfo would be a good extension to
the WMS format. If you dont really need to execute against multiple
layers, then consider using WFS getFeature instead where you can specify
propertynames. ( My maps have the concept of “active layer” for use in
all searching, hover controls etc.)
Actually, I see that propertynames (exclude the shape from list) is a
geoserver vendor option for single layer getFeatureInfo. If using OL,
you would need to make sure that is in the options parameter for the
control, rather than using the propertyNames parameter of the
getFeatureInfo control (which filters the fields AFTER the call).
returnGeometry=true/false would be a better extension however because it
would with multiple layers.

–
Phil Scadden, Senior Scientist GNS Science Ltd 764 Cumberland St,
Private Bag 1930, Dunedin, New Zealand Ph +64 3 4799663, fax +64 3 477 5232

Notice: This email and any attachments are confidential.
If received in error please destroy and immediately notify us.
Do not copy or disclose the contents.

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