[OSM-dev] Rendering: 2 questions.

Rogier Wolff R.E.Wolff at BitWizard.nl
Fri Aug 8 13:28:46 BST 2008



Hi, 

I was considering volunteering some of my machines for tiles at home,
but the readme told me that it required up to a gigabyte of RAM.

As Linux doesn't allow me to tell the OS to only run that program if
I don't need the RAM for other stuff, that's just too much, so I can't
participate. Then I got to thinking: 256x256 pixels for a tile is 
only very little. So why the lots of RAM?

It seems that a bunch of tiles, 32x32 of them, are rendered at once. 

This would result in a 64 megapixel image, which at 4 bytes per pixel
results in at least 256 Mbyte of required RAM.

Would it be an idea to allow users to specify something like what
order their tah client should work at? So I could specify: Zoom level
14. This means that instead of working on one level 12 image, I'll
work on 16 level 12 images, hopefully cutting the memory requiremes by
close to 16...

Now from a server point-of-view, it's not desirable if different
chunks get processed. So, instead of allowing different sizes to be
downloaded, the client, configured for non-level-12 operation would
then itself work on the different subtiles, instead of all at once...



Secondly, I added the road where my brother lives, how long should it
take to render that tile again?

http://www.openstreetmap.com/?lat=52.017163&lon=4.362137&zoom=18&layers=B00FTF

(there should now be a street going north-east from the oostsingel in
the larger block across from the postbox. That street doesn't go all
the way to the van miereveldlaan. The Yahoo images show the street and
the houses there still being built, but they are finished now :-)

It is an enormous motivation for people to actually see the results of
their work. So if I don't see the results of my edit, I'll lose
interest in OSM, and stop correcting the database.... 


	Roger. 

-- 
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