Cool - thanks for the additional info.
On Fri, Mar 6, 2009 at 7:28 PM,
<hbypf@xxxxxxxxxxxx> wrote:
Hi Jody and all who answered the call.
I'm sorry for my obscure description of the problem of drawing map in udig(v1.1.1) last time.
Firstly,I'm a user.The datasets l use was small.The most I want is the perfomance of map rendering,I hope when I operate the maps(ie, drag ,pan) ,the maps(including raster and vector layers) display smoothly without flickering .In this situation,what I could do?Thinks!
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As a developer I have seen people load up their data into a SpatialIndex (literally the SpatialIndex class from the JTS library we use to represent geometry). This is suitable for small data sets that fit in memory and can very quickly tell us what data is in a given bounding box (ie what data is on the screen).
There is a geotools datastructure called MemoryDataStore that *does not* do this right now. So you would be looking at doing some hands on work.
To get started in this area review the following three tutorials source code:
- net.refractions.udig.tutorials.csvservice
- net.refractions.udig.tutorials.renderer
- net.refractions.udig.tutorials.style
The developer I saw who put together the spatial index for speed stored the spatial index on the layer blackboard; and the renderer would check if the spatial index was available and draw faster if it was available. If it was not available it would draw as it constructed the spatial index the first time.
Emily also has an example of providing in memory caching for WFS data (this was fun because she grabbed data into memory as needed).
Finally try out the experimental release of udig mentioned before; and turn on the tiled rendering system in Window > Preferneces (and then close and reopen your map).
Secondly,I'm a developer.What I want mostly is the same thing I mention above.In this situation,what I could do?Could you give me some advice and solution?Thinks a lot! |
I am afraid uDig 1.1.1 is set up to make large data possible; it is only in uDig 1.2 that we are starting to experiment with using memory to provide faster performance. Why not join us and try out some idas of your own.
In addition, the raster layer I mentioned is such as the clouds.jpg ,that's all ,think you!
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So you will need to join us on udig 1.2 and try out the performance there; you can then talk to the developers about how to prepair your data for speed. Or make use of a tiled map server as mentioned in the previous email.
Jody
