[GRASS5] [OFFTOPIC] Need some help...

[Muzaffer Ayvaz]

  Hi;
   
  http://grass.itc.it/searchgrass.php
   
  may help you to search mailing list archives.
   
  Muzaffer...

Dmitry Suzdalev <dimsuz at mail.ru> wrote:
  Hi, dear GRASS developers :).
Please, sorry for maybe offtopic, but I have one question.
I'm learning my way into world of map projections and my task is to display 
all the world in a GUI window (QT-window, actually).
I've already managed to do it, using libproj4 :).
But... There is sooo much data to be displayed that it draws rather slow.

And it's obvious, that it's not needed to draw EACH map data primitive, 
because some of them are so small, that they're represented by one pixel, 
when using large scales. And still, if I have 1000 primitives (polylines, 
regions etc) that are so small, that they fit in one concrete pixel, they'll 
all be drawn. In the same pixel. 1000 times. That's slow :).

So the question is: is there any common algorithm to cope with this situation? 
Which helps to somehow "filter out" the primitives which are represented by a 
single pixel at the screen and draw that pixel only once?
Or should i investigate that algorithm by myself? :)

Again, sorry if this is offtopic, I've googled for a few hours trying to find 
some kind of web-forum for such kind of questions, but I didn't find it :).
Googling on "gis developers forum" pointed me to your mailing list, so I 
decided to give it a try :).

Maybe at least, you can point me to the right place to ask such a question? :)

Thanks in advance!

And sorry for my maybe not very good English ;).
Cheers, Dmitry.

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