On Tue, Sep 27, 2011 at 8:10 PM, Martin Dobias <[email protected]> wrote:
> On Tue, Sep 27, 2011 at 4:18 PM, Mohammed Rashad > <[email protected]> wrote: > > Hi All, > > I am developing tiled vector rendering in OSSIM. I like the Qgis vector > > rendering system > > point.shp contains 9,99,999 points which are generated by grass for using > > v.random and ~27MB in size > > roads.shp contains 2,28,068 linestrings and is ~50MB in size > > these point.shp and roads.shp data gets rendered in ~10 sec > > When I read vector using ogr and parse feature and draw point/linestring > my > > application taking about 40 sec to render point.shp > > and > > I am using Qt4 with QPainter not QGraphicsView > > How came this time gap? > > Most likely you have some inefficiencies in your implementation. > Can you tell where i have inefficiencies I do direct rendering Qt Painter and OGR? > > > i see Rtree and pal libs in src/core source code > > Does they have any role in rendering? > > No - unless you also draw labels. > > > Does QGIS Rendering uses threading? > > No - only in threading branch which has not yet been integrated. > > > How to get a minimal of QGIS code to hack it and build a new vector > > rendering because I need it to make it tiled rendering vectors? > > You can use qgis_core library to do tiled drawing. > > > How to improve performance in rendering without qgis? > > Learn how to profile programs - i.e. get time spent in individual > functions, analyze the results and fix the places where most of the > time is spent. > How to do profiling? how is works? please tell me some samples for profiling.. > > Martin > -- Regards, Mohammed Rashad K M M.S. (By Research) student Lab for Spatial Informatics Department of CSE International Institute of Information Technology Hyderabad, India
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