[mapserver-users] Re: Dynamic data loading using Google maps andMapserver

Steve Lime Steve.Lime at dnr.state.mn.us
Thu May 7 10:32:58 PDT 2009


Something's backwards, you're mapxy is 38.87795, -77.098617 but your extents are neg,pos,neg,pos? Also
is your data in lat/lon?

Steve

>>> On 5/7/2009 at 12:27 PM, in message
<6db14d250905071027j7ff0aac8j30edeb7f8c9389e3 at mail.gmail.com>, Varun saraf
<vsaraf.gmu at gmail.com> wrote:
> Hi All,
> 
> I am trying to integrate the census tracts on the google maps base. I
> am using the tile mode and have successfully drawn the shape files
> over the states of USA. I have some data in an access database that I
> need to show to the user when he selects a particular census tract
> (the shapes are polygons). However, since its a tile mode that I am
> using on google maps, I am unable to understand how do I get the
> information from mapserver as to which census tract was selected by
> the user? Is there a way mapserver can send me the polygon selected
> based on a co-ordinate lying inside the polygon? I know there is a way
> by using queries and a querymap for doing this. The query that I am
> using is as follows
> 
> http://127.0.0.1:8123/cgi-bin/mapserv.exe?&map=C:/ms4w/apps/census/testMap.map& 
> mode=query&mapxy=38.87795
> -77.098617
> 
> I am providing a template in my map file that has the tract variables.
> However, the result is always the same
> 
> "msQueryByPoint(): Search returned no results. No matching record(s)
> found." Is it that mapserver is trying to look for a point feature in
> the location specifies by mapxy in the link above? How do I make
> mapserver to look for a polygon enclosing this co-ordinate and return
> me the result? I am attaching my mapfile also for reference.
> 
> MAP
>     NAME testMap
>     STATUS ON
>     SIZE 600 300
>     EXTENT -84 37 -75 40
>     UNITS DD
>     SHAPEPATH "data"
>     IMAGECOLOR 255 255 255
>     CONFIG "MS_ERRORFILE" "ms_error.txt"
> 
>     IMAGETYPE PNG
> 
>     WEB
>       IMAGEPATH "/ms4w/tmp/ms_tmp/"
>       IMAGEURL "/ms_tmp/"
>     END
> 
>     QUERYMAP
>         STATUS ON
>         STYLE HILITE
>     END
> 
>     LAYER
>         NAME "virginia"
>         STATUS DEFAULT
>         TYPE polygon
>         DATA tr51_d00
>         DEBUG 5
>         TOLERANCE 1000
>         TOLERANCEUNITS pixels
> 
>         TEMPLATE "bodytemplate.html"
>         HEADER "imapheader.html"
>         FOOTER "imapfooter.html"
> 
>         CLASS
> 	   STYLE
> 	      OUTLINECOLOR 128 128 128
> 	      COLOR 153 205 255
> 	    END
> 	   TEMPLATE "pointTemplate.html"	
> 	END
> 
>     END
> END
> 
> Thanks,
> Varun
> 
> On Mon, May 4, 2009 at 3:30 PM, Varun saraf <vsaraf.gmu at gmail.com> wrote:
>> Hi Steve,
>>
>> If I provide Mapserver with a point x,y in WGS84 projection (from
>> google maps) as a query, can mapserver give me the enclosing polygon
>> information (using point-in-polygon method or something else)? If yes,
>> how? I have already drawn the polygons on google map using tile mode.
>> Can you suggest me a book/doc that helps with querying mapserver?
>>
>> Thanks,
>> Varun
>>
>> On Sun, May 3, 2009 at 9:56 AM, Steve Lime <Steve.Lime at dnr.state.mn.us> wrote:
>>> Both examples show how to do this. You have to create a query using
>>> the coordinate from Google to access MapServer. My example uses the
>>> principle to query points but would work for polygons (which are actually
>>> easier). You could issue straight MapServer queries:
>>>
>>>  
> http://.../cgi-bin/mapserv?mode=query&map=something.map&mapxy=google_x+google_y 
> &qlayer=the_polygons
>>>
>>> or do a WFS query. Since you're already using straight MapServer the former
>>> would probably be easiest.
>>>
>>> Steve
>>>
>>>>>> Varun saraf <vsaraf.gmu at gmail.com> 05/02/09 1:34 PM >>>
>>> Hi,
>>>
>>> Thanks a lot Jim and Steve. These are great examples but I am dividing
>>> each state of USA into about 1300 polygons and I need a way to find
>>> which polygon is selected by the user. I tried building Gpolygons
>>> using the polygon data that i have (after converting it into a GML
>>> file) but it makes Google damn slow to redraw the polygons on zoom in
>>> and zoom out. The tile mode in mapserver is much faster.
>>>
>>> Now, After I draw the polygon in tile mode using mapserver, Is there a
>>> way Mapserver can return to me the specific polygon info (say
>>> co-ordinates or any other data in the dbf file relating to that
>>> polygon) when I select it on google map? Goggle I believe can give me
>>> the exact co-ordinates of the point I clicked. Can mapserver use this
>>> point location to find which polygon was selected?
>>>
>>> Thanks,
>>> Varun
>>>
>>> 2009/5/2 Jim Strevinas <voas_acc at hotmail.com>:
>>>> A beautiful example that uses the Google Maps API is:
>>>>
>>>> http://www.dyasdesigns.com/geoxml/gmlusa.htm 
>>>>
>>>> It makes use of an API plugin called geoxml that can load XML data which can
>>>> be produced by
>>>> a WFS server. In the source code, a static GML file is used but a google
>>>> search shows that it can
>>>> connect to a live WFS server using the URL.
>>>>
>>>>> Date: Sat, 2 May 2009 09:28:01 -0500
>>>>> From: Steve.Lime at dnr.state.mn.us 
>>>>> To: vsaraf.gmu at gmail.com 
>>>>> Subject: Re: [mapserver-users] Re: Dynamic data loading using Google maps
>>>>> andMapserver
>>>>> CC: mapserver-users at lists.osgeo.org 
>>>>>
>>>>> One way to do that is to construct MapServer queries based on the event
>>>>> and submit them using AJAX. This site does just that but with OpenLayers:
>>>>>
>>>>> http://www.dnr.state.mn.us/waters/csg/index_copy.html 
>>>>>
>>>>> Click on the dots and a MapServer query is done behind the scenes. If
>>>>> successful
>>>>> a little window control is populated, if not, then nothing happens. Simple
>>>>> templates
>>>>> are used to present the information.
>>>>>
>>>>> Steve
>>>>>
>>>>> >>> Varun saraf <vsaraf.gmu at gmail.com> 05/01/09 11:54 AM >>>
>>>>> Hi,
>>>>>
>>>>> I just had a look at ImageMap Template on "Output generation"...Can
>>>>> this be used on google maps to get information pooped up on a
>>>>> mouseover or mouseclick in tile mode? If not, what is it that I can do
>>>>> to get a similar result when using Mapserver with google maps?
>>>>>
>>>>> Regards,
>>>>> Varun
>>>>>
>>>>> On Thu, Apr 30, 2009 at 6:30 PM, Varun saraf <vsaraf.gmu at gmail.com> wrote:
>>>>> > Hi,
>>>>> >
>>>>> > I have successfully drawn layers on of google maps as base using
>>>>> > mapserver. However, I am trying to figure out how to get data
>>>>> > dynamically displayed on the web page when a user clicks on a certain
>>>>> > area. For example, I have divided the entire state of virginia into
>>>>> > many sectors (using a polygon shp file). My requirement is that I want
>>>>> > data to come up on the map/web page when the user selects a particular
>>>>> > sector. I know google provides me with an event api for clicking on
>>>>> > the map but how do I pass this event to mapserver so it can send me
>>>>> > the label for that sector from the shape file? I need to be able to
>>>>> > recognize what sector the user has clicked. Is this possible using
>>>>> > just the mapserv cgi script and a map file or a MapScript has to be
>>>>> > written/used? Can someone point me in the right direction here? Even
>>>>> > providing the link for a previous discussion on this topic would help.
>>>>> >
>>>>> > Thanks,
>>>>> > Varun
>>>>> >
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