Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
On Wed, May 9, 2012 at 10:43 PM, cheesybiscuits thomaschrist...@gmail.com wrote: I know this is an old thread but I was thinking about how getFeatureInfo might work under the covers and Andrea's description of layer ordering and only querying what the user can see is what I would expect to happen. Regarding most servers just query all the layers without checking what is hidden and what is visible graphically does this include GeoServer (2.1.3)? I also assumed that the server would consider symbology, so if I have a 250x250 px icon GeoServer would know that I didn't have to click on or near the underlying geographic location to select it. Are my expectations / assumptions correct, or is GetFeatureInfo's logic actually less sophisticated? Hum, yes and no. The code in the released version tries to take into account all symbolizer sizes, but due to this bug https://jira.codehaus.org/browse/GEOS-5112 the buffer distance evaluator did not take into account the size of external graphics unless you explicitly declared it in the SLD file, but leaving instead the icon at its natural size. The issue should be fixed now, if you want to try out the fix try using the latest nightly build here: http://gridlock.opengeo.org/geoserver/2.1.x/ Cheers Andrea -- Ing. Andrea Aime GeoSolutions S.A.S. Tech lead Via Poggio alle Viti 1187 55054 Massarosa (LU) Italy phone: +39 0584 962313 fax: +39 0584 962313 mob: +39 339 8844549 http://www.geo-solutions.it http://geo-solutions.blogspot.com/ http://www.youtube.com/user/GeoSolutionsIT http://www.linkedin.com/in/andreaaime http://twitter.com/geowolf -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
I know this is an old thread but I was thinking about how getFeatureInfo might work under the covers and Andrea's description of layer ordering and only querying what the user can see is what I would expect to happen. Regarding most servers just query all the layers without checking what is hidden and what is visible graphically does this include GeoServer (2.1.3)? I also assumed that the server would consider symbology, so if I have a 250x250 px icon GeoServer would know that I didn't have to click on or near the underlying geographic location to select it. Are my expectations / assumptions correct, or is GetFeatureInfo's logic actually less sophisticated? -- View this message in context: http://osgeo-org.1560.n6.nabble.com/What-s-the-difference-between-LAYERS-and-QUERY-LAYERS-parameters-in-GetFeatureInfo-request-tp3788587p4964007.html Sent from the GeoServer - User mailing list archive at Nabble.com. -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
Hi, That all comes from WMS standard and it is rather well written there http://portal.opengeospatial.org/files/?artifact_id=1081version=1format=pdf Logic goes somehow in opposite direction than what you planning to do. It assumes that user has made a GetMap request and sees a map on a screen. It is just an image and does not include any information about georeferencing. If use is clicking on a map the client software can only record which pixel was clicked. However, the georeferencing can be computed on the WMS server side if the WMS GetMap request with BBOX and image size is known. LAYERS just need to be in the request because standard says so but QUERY_LAYERS is the one used for selecting layers to be queried. They do not need to be the same. For creating GetFeatureInfo requests from a scratch you will need to do some calculation. The the centre point, decide some image size in WIDTH and HEIGHT and compute BBOX according to those. -Jukka Rahkonen- Gis Mage wrote: Hi list, I've got a couple of questions regarding a GetFeatureInfo request. 1. Why should I put both LAYERS and QUERY_LAYERS in the request? I doesn't work with only one of those params, but I put in the same list of layers in both params all the time. What's the difference between them? 2. Why do I have to put both BBOX and HEIGHT, WIDTH params in the request? I guess the server draws a map with the requested bbox, height and width, and then takes x and y, transforms to coordinates and executes a query. But that is just a blind guess and seems a bit strange. So, pretend I want to get info for specified layer, it's in EPSG:4326 and lat/lon of the point is (-104.97,39.71). How do I calculate the BBOX, HEIGHT, WIDTH, X and Y of the request? Is it somehow different if a layer is in EPSG:900913? -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
On 11 November 2011 09:07, Rahkonen Jukka jukka.rahko...@mmmtike.fi wrote: Hi, That all comes from WMS standard and it is rather well written there http://portal.opengeospatial.org/files/?artifact_id=1081version=1format=pdf Logic goes somehow in opposite direction than what you planning to do. It assumes that user has made a GetMap request and sees a map on a screen. It is just an image and does not include any information about georeferencing. If use is clicking on a map the client software can only record which pixel was clicked. However, the georeferencing can be computed on the WMS server side if the WMS GetMap request with BBOX and image size is known. LAYERS just need to be in the request because standard says so but QUERY_LAYERS is the one used for selecting layers to be queried. They do not need to be the same. LAYERS is there because in theory you can just change the request from getmap to getfeatureinfo and concatenate the click location and query layer and send it back. This meant that back in the early days before JavaScript became popular you could create a WMS client with some cgi shell scripts and a submit button in ah HTML form. For creating GetFeatureInfo requests from a scratch you will need to do some calculation. The the centre point, decide some image size in WIDTH and HEIGHT and compute BBOX according to those. If you find that you are having to do that sort of calculation then you should probably be using a WFS getFeature request instead of a WMS getFeatureInfo. Ian -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
Thanks, guys! I'm just looking for a way to reduce the length of a request, because I'm requesting a lot of layers at once. Layer group is not an option, because the list of the layers is being formed programatically. WFS GetFeature is cool, but I guess it requires proxy - I have to investigate that. So the smaller the BBOX and HEIGHT/WIDTH, the faster a client gets a response, right? 2011/11/11 Ian Turton ijtur...@gmail.com: On 11 November 2011 09:07, Rahkonen Jukka jukka.rahko...@mmmtike.fi wrote: Hi, That all comes from WMS standard and it is rather well written there http://portal.opengeospatial.org/files/?artifact_id=1081version=1format=pdf Logic goes somehow in opposite direction than what you planning to do. It assumes that user has made a GetMap request and sees a map on a screen. It is just an image and does not include any information about georeferencing. If use is clicking on a map the client software can only record which pixel was clicked. However, the georeferencing can be computed on the WMS server side if the WMS GetMap request with BBOX and image size is known. LAYERS just need to be in the request because standard says so but QUERY_LAYERS is the one used for selecting layers to be queried. They do not need to be the same. LAYERS is there because in theory you can just change the request from getmap to getfeatureinfo and concatenate the click location and query layer and send it back. This meant that back in the early days before JavaScript became popular you could create a WMS client with some cgi shell scripts and a submit button in ah HTML form. For creating GetFeatureInfo requests from a scratch you will need to do some calculation. The the centre point, decide some image size in WIDTH and HEIGHT and compute BBOX according to those. If you find that you are having to do that sort of calculation then you should probably be using a WFS getFeature request instead of a WMS getFeatureInfo. Ian -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
Hi, I do not believe that the size of BBOX and HEIGHT/WIDTH has any effect at all. The mathematics for finding the coordinates of the selected pixel is always the same. Server does not ever render that image if you are thinking about that. One thing you would probably know about Geoserver is that I just learned that it is applying a buffer to the coordinates and by default it is three image pixel wide. Otherwise it would be practically impossible to find any points or linear features. You can control that with Geoserver vendor parameter buffer. -Jukka Rahkonen- Gis Mage wrote: Thanks, guys! I'm just looking for a way to reduce the length of a request, because I'm requesting a lot of layers at once. Layer group is not an option, because the list of the layers is being formed programatically. WFS GetFeature is cool, but I guess it requires proxy - I have to investigate that. So the smaller the BBOX and HEIGHT/WIDTH, the faster a client gets a response, right? 2011/11/11 Ian Turton ijtur...@gmail.com: On 11 November 2011 09:07, Rahkonen Jukka jukka.rahko...@mmmtike.fi wrote: Hi, That all comes from WMS standard and it is rather well written there http://portal.opengeospatial.org/files/?artifact_id=1081versi on=1format=pdf Logic goes somehow in opposite direction than what you planning to do. It assumes that user has made a GetMap request and sees a map on a screen. It is just an image and does not include any information about georeferencing. If use is clicking on a map the client software can only record which pixel was clicked. However, the georeferencing can be computed on the WMS server side if the WMS GetMap request with BBOX and image size is known. LAYERS just need to be in the request because standard says so but QUERY_LAYERS is the one used for selecting layers to be queried. They do not need to be the same. LAYERS is there because in theory you can just change the request from getmap to getfeatureinfo and concatenate the click location and query layer and send it back. This meant that back in the early days before JavaScript became popular you could create a WMS client with some cgi shell scripts and a submit button in ah HTML form. For creating GetFeatureInfo requests from a scratch you will need to do some calculation. The the centre point, decide some image size in WIDTH and HEIGHT and compute BBOX according to those. If you find that you are having to do that sort of calculation then you should probably be using a WFS getFeature request instead of a WMS getFeatureInfo. Ian -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
On 11 November 2011 09:30, Gis Mage gism...@gmail.com wrote: Thanks, guys! I'm just looking for a way to reduce the length of a request, because I'm requesting a lot of layers at once. Layer group is not an option, because the list of the layers is being formed programatically. You only need to set the actual layer you are interested in in both LAYERS and QUERY_LAYERS WFS GetFeature is cool, but I guess it requires proxy - I have to investigate that. Actually a getFeatureInfo request will require a proxy too (iff you are running the server on a different host/port combo than the map). So the smaller the BBOX and HEIGHT/WIDTH, the faster a client gets a response, right? Not really but you'll lose accuracy if you make them too small. Ian -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 ___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
Re: [Geoserver-users] What's the difference between LAYERS and QUERY_LAYERS parameters in GetFeatureInfo request?
On Fri, Nov 11, 2011 at 10:20 AM, Ian Turton ijtur...@gmail.com wrote: On 11 November 2011 09:07, Rahkonen Jukka jukka.rahko...@mmmtike.fi wrote: Hi, That all comes from WMS standard and it is rather well written there http://portal.opengeospatial.org/files/?artifact_id=1081version=1format=pdf Logic goes somehow in opposite direction than what you planning to do. It assumes that user has made a GetMap request and sees a map on a screen. It is just an image and does not include any information about georeferencing. If use is clicking on a map the client software can only record which pixel was clicked. However, the georeferencing can be computed on the WMS server side if the WMS GetMap request with BBOX and image size is known. LAYERS just need to be in the request because standard says so but QUERY_LAYERS is the one used for selecting layers to be queried. They do not need to be the same. LAYERS is there because in theory you can just change the request from getmap to getfeatureinfo and concatenate the click location and query layer and send it back. This meant that back in the early days before JavaScript became popular you could create a WMS client with some cgi shell scripts and a submit button in ah HTML form. I believe this is a valid reason, but there is also a better one. GetFeatureInfo theretically should tell info about you what you clicked. Say I have a point layer and a polygon layer, the polygons contain all the points, and you want to query them. If the points are above the polygons the correct answer would contain some points data (provided you clicked close enough to one). But if the polygons are above the points instead, in theory you should not get any info because you are actually not seeing them. The layer ordering can only be detemined by having LAYERS Now, that said, most servers just query all the layers without checking what is hidden and what is visible graphically, so they would return points in both cases. Cheers Andrea -- --- Ing. Andrea Aime GeoSolutions S.A.S. Tech lead Via Poggio alle Viti 1187 55054 Massarosa (LU) Italy phone: +39 0584 962313 fax: +39 0584 962313 http://www.geo-solutions.it http://geo-solutions.blogspot.com/ http://www.youtube.com/user/GeoSolutionsIT http://www.linkedin.com/in/andreaaime http://twitter.com/geowolf --- -- RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1___ Geoserver-users mailing list Geoserver-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geoserver-users
