Hi JR,
There is a com.bbn.openmap.layer.util.cacheHandler package to help
with caching. It uses a least-recently-used algorithm. You just
have to extend CacheHandler so it implements the load(String) method,
creating the CacheObjects for it.
Also, there is a WKB implementation out there for OpenMap:
http://wkb4j.sourceforge.net/
Hope this helps,
Don
On Jul 31, 2006, at 9:05 PM, JR Andreassen wrote:
> Hello Again...
> I've created a Layer for DB/2 Geospatial Extender...
> I based it on the mySQL version.
>
> It works, but it is so slow that it's not usable.
>
> Two problems:
>
> 1) WellKnownText conversion is way too slow.
> 2) It refetches all the objects from the DB every time.
>
> So, is there a caching Layer object I could inherrit from instead
> of OMGraphicHandlerLayer?
> Has anyone done anything with WellKnownBinary ??
>
> Thanks
> JR
>
>>
>> On Jul 27, 2006, at 4:35 PM, JR Andreassen wrote:
>>
>>> Thanks for getting back to me.
>>>
>>>>> Issues so far:
>>>>> How to you specify the base map ?
>>>>
>>>>
>>>>
>>>> You would configure a layer to display the data you want. For
>>>> the default OpenMap application, the layers are specified and
>>>> configured in the openmap.properties file. That file has
>>>> instructions for modifying itself.
>>>>
>>>>> I can't find any reference on where to change the base map Image.
>>>>> (Or is there a way to specify a Shape/other as the background)
>>>>>
>>>>> Does it /How do I handle Quadrangle/TIFF images ?
>>>>
>>>>
>>>> The easiest way to display images is to use the
>>>> CSVTiledImagePlugIn. The JavaDocs for the CSVTiledImagePlugIn
>>>> describe how to create a CSV file that list the images and
>>>> their locations, and the plugin can be added as a layer to
>>>> the application (via the openmap.properties file), with that
>>>> csv file noted in the properties for that plugin.
>>>> I'm not sure if TIFFs are handled by the general JRE, come to
>>>> think of it. You might have to install the JAI package (Java
>>>> Advanced Imaging) to get TIFF functionality.
>>>
>>>
>>> I can handle that...
>>>
>>>>> Does it /How do I handle Segmented data and transitions?
>>>>> We have several datasets that we'll be based on
>>>>> (http://www.capcog.org/Information_Clearinghouse/
>>>>> geospatial_main.asp)
>>>>> These data sets(roads, etc) are split into areas(counties)
>>>>> since they are rather large.
>>>>
>>>>
>>>> Shape files can be read to create OMGraphics, which are the
>>>> objects rendered to the map. They know how to position and
>>>> render themselves. There are Layers that create OMGraphics
>>>> out of Shape files, and one (MultiShapeLayer) that handles
>>>> more than one Shape file. If you are going to have a lot of
>>>> data...
>>>>
>>>>> Does it /How do I handle monster datasets ?
>>>>
>>>>
>>>> you should load the data sets into a database (MySQL, PostGRES
>>>> with PostGIS, Oracle) and use a layer to retrieve the
>>>> geometries from the database based on the projection.
>>>
>>>
>>> Newbie question: Is the projection your subset of the world vs
>>> "zoom-factor" ?
>>
>>
>> The projection is a description of the map window - there's a
>> projection type associated with the object, a center point of the
>> projection at the center of the window, a scale, and pixel height/
>> width.
>>
>> Projection's forward() methods translate lat/lons to pixel
>> coordinates, and inverse() methods translate pixel coordinates to
>> lat/ lon coordinates.
>>
>> The MapBean (the main map window object) controls the Projection
>> object and lets its layers know when it has changed.
>>
>>> Can you make a projection that is relative to the "current
>>> possition" with no refresh until you reach a certain offset from
>>> the edge ?
>>
>>
>> You can change the projection on the MapBean whenever you like.
>> The layers are reactionary to the MapBean's notifications. If a
>> layer needs to change the projection, it has to tell the MapBean.
>>
>>
>>>> A MySQL layer is part of the distribution, and an
>>>> OracleSpatialLayer was posted to the mailing list and is
>>>> available in the archives.
>>>
>>>
>>> The DB approach is appealing to us, since we have a DBM(DB/2) on
>>> each machine. The problem with the DB/2 GeoSpatial extender is
>>> that it's $9k per machine.
>>> Given that we have over 2K users that's way outside our budget.
>>> So, is there a X./Open standard for GeoSpatial data ?
>>> I might be able contribute some in that area.....
>>
>>
>> The Open GIS Consortium (OGC) has a standard for storing data in
>> a database, Simple Features for SQL.
>>
>> I don't know if there is an open source DB2 geospatial extender,
>> or if you want to add one of the other free databases to your
>> machines to handle large amounts of spatial data.
>>
>> - Don
>>
>>
>>
>>
>>>> Does it /How do I handle Lat/Lon to Layer serches ?
>>>> If you are using a database with large datasets, it's probably
>>>> better to do the search on the database. You can also work
>>>> with the OMGraphics to do spatial searches for those objects
>>>> rendered on the map.
>>>>
>>>> There's a developer's guide available at:
>>>
>>>
>>> Got that one...
>>>
>>>> Hope this helps,
>>>
>>>
>>> It does indeed...
>>>
>>> Thanks
>>> JR
>>>
>>> JR Andreassen
>>> Strategic Database Inc.
>>>
>>> --
>>> [To unsubscribe to this list send an email to "majdart_at_bbn.com"
>>> with the following text in the BODY of the message "unsubscribe
>>> openmap-users"]
>>
>>
>>
>>
>> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>> Don Dietrick, dietrick_at_bbn.com
>> BBN Technologies, Cambridge, MA
>> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>>
>>
>> --
>> [To unsubscribe to this list send an email to "majdart_at_bbn.com"
>> with the following text in the BODY of the message "unsubscribe
>> openmap-users"]
>>
>
> --
> [To unsubscribe to this list send an email to "majdart_at_bbn.com"
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Don Dietrick, dietrick_at_bbn.com
BBN Technologies, Cambridge, MA
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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Received on Tue Aug 01 2006 - 13:12:49 EDT