I am unsure if you are asking some of these questions as a user or as a developer? Some replys inline...
On Fri, Mar 6, 2009 at 12:06 PM,
<hbypf@xxxxxxxxxxxx> wrote:
Hi,people!
I'm a new user in using udig.I'm using version1.1.1 of udig. |
Welcome!
I found a problem when I operate a map consisting of three layers including a vector layer and a raster layer.
|
Do you mean a raster layer such as the clouds.jpg (in the sample dataset) or do you mean a raster layer such as a web map server? Both these kinds of data have different performance characteristics.
The problem is the map flashes very quickly when dragging or moving it,and the map redarws very slowly.I have checked the configuration of my pc,it works well with 2-core cpu and 128M display card. |
uDig does not load the data into memory if it can avoid it - this is to allow you to work with very large datasets. There is a cost in terms of rendering performance; but for most spatial formats the tradeoff is worthwhile. Please note that some formats need help to be fast (shapefiles really like a spatial index; raster files really like having something called an overlay created for them).
If you download the experimental uDig 1.2 release you will be able to check out:
- a new raster pipeline that has different performance characteristics - it is even better at letting me work on large rasters.
- a tiled rendering system (which uses memory to allow you do flicker free panning; it only draws new "tiles" as you pan around).
- wms-c (ie an alternative to web map server that uses tiles; the implementation will store tiles on your local disk if you like offering amazing performance).
But why ? Is it possible that udig have a bug of redrawing map?Plesase send me some advice ,thinks a lot!
|
Based on your description I think this may be by design; we have had some issues with the map flashing in the past - so I would need a bit more of a description to determine this is if a bug.
By the way ,who can tell me the principle or process of the map drawing of the uDig?
|
Does the above description help?
And what are the components of drawing map? |
The components (Map/Layer and GeoResource/Renderer) are described in the developers guide; or in some commercial training course materials (these materials are recommended and we are able to make them available to academic users free of charge).
How these components constitute? |
These components are put together with the Eclipse Rich Client platform - a really nice system of plug-ins that is also used by the Eclipse IDE. Recently this plugin system has starting making use of OSGi technology offering a really respectable degree of safety when working with many components.
好玩贺卡等你发，邮箱贺卡全新上线！
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