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Large Shape File Not Optimization OK

May 25, 2011 at 2:53 AM

Current In MapWinGIS4.8.2 Large Shape File Optimization does not good.

My machine's hardware: Intel T2400@1.83GHz, 1G Memory, ATI Mobility Radeon X1300.

I test a Shape file with 200,000 entities in MapWinGIS and MapX5,

In full layer view, they two are slow, approximately 4s,

but when I zoom to large scale, even if only see several entities, MapWinGIS also spent 1s, MapX spent little time.

Jun 14, 2011 at 3:53 PM

I've just tried to to display 200+ MB shapefile in MapWindow 4. The redraw time at full scale is around 6 seconds (15 seconds without optimizations). But when zooming closer (several shapes) it uses around 0.2 sec (Map.ShowRedrawTime - displays time used by ocx drawing routine). In fact more time is used. But those are the problems of MW4 code.

So the 1sec you see is clearly too much. Do you use spatial index? 

To achieve maximum speed you need to set:

Shapefile.FastEditMode = true;

Shapefile.CreateSpatialIndex(...);   //Shapefile.UseSpatialIndex should return true

Shapefile.MinDrawingSize = 5;   // shapes with size less than this will be drawn as points

Sergei