[mapserver-users] Showing pop up for a line

[Subha Ramakrishnan]

Hi,

Thanks a lot for the reply.

If i use  
"ST_Contains(topology,st_expand(geomFromText('POINT(77.87117958068927 
 13.491965860913544)',-1), 10)", can it be the case that more than one 
record will match the condition? And this will not work for me, as I 
need to have exactly one record to show the pop up.

The constraint I'm facing in using Openlayers to draw the line layer is 
that the layer is too huge consisting of more than 20,000 features and 
the browser hangs because of too much memory being used in drawing the 
layer. Hence I am using mapserver for drawing the line layer.

I did try other options here. The operator "~" [A ~ B (A completely 
contains B)] gives me more than one line(record) that matches the 
condition. But this cannot be the case to show the pop up. I did try to 
club it with other operators like "&&" and "=" but none of these seem to 
work.

Thanks again.

Regards,
Subha



Dan Little wrote:
> In my experience it's easier to do a buffer on the line features first (something nominal) which turns it into a polygon.  In this way, the operators you want to use work consistently.
>
>
> ----- Original Message ----
>   
>> From: Subha Ramakrishnan <subha at gslab.com>
>> To: Steve Lime <Steve.Lime at dnr.state.mn.us>
>> Cc: mapserver-users at lists.osgeo.org
>> Sent: Tuesday, January 6, 2009 12:04:13 AM
>> Subject: [mapserver-users] Showing pop up for a line
>>
>> Hi,
>>
>> I am using Mapserver 5.0.2 with Openlayers.
>> I've a line layer (from mapserver) shown on my base map(google physical).
>> Now, when i click on a line, i want to show a pop using openlayers.
>> I am able to do this for a polygon layer. I send the lat,lon of the point that 
>> is clicked and use the postgis query
>> "ST_Contains(topology,geomFromText('POINT(77.87117958068927  
>> 13.491965860913544)',-1))" to find the polygon (and fetch the polygon specific 
>> data to show on pop up) and attach the Openlayers popup to the point clicked.
>>
>> I am not able to do this for a line layer as the postgis query doesn't return 
>> anything.
>> I tried this query also, 
>> "ST_Contains(topology,geomFromText('POINT(77.87117958068927  
>> 13.491965860913544)',-1)) AND 
>> distance(topology,geomFromText('POINT(77.87117958068927 
>> 13.491965860913544)',-1)) <= 1" but it doesn't work.
>>
>> Does any one know how to check if a point is a part of a line or if there is any 
>> other way to show the pop up?
>>
>> Thanks a lot for the help.
>>
>> Regards,
>> Subha
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>> mapserver-users at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapserver-users
>>     
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