Explorer2000
Posts: 10
Joined: Sun Sep 18, 2005 7:29 pm

suggestion for improving raster loading

Mon Nov 20, 2006 8:56 pm

Hello johan,
I think when we make a maplib from raster at that time raster file should cut into tiles by maplib and stored accordingly.the raster has index of all tiles and it should load only those tiles in memory which are required.this method is used by google map.it store all raster mapinto tiles and load only tiles which are required.
please feel free for any comments and query.

Explorer2000

Jonas
Posts: 2319
Joined: Mon Jan 09, 2006 2:20 pm
Location: Sweden

RE: suggestion for improving raster loading

Mon Nov 20, 2006 10:01 pm

This is how MapLib works.

Regards,
Jonas
Franson Support

Guz
Posts: 47
Joined: Tue Sep 21, 2004 7:57 pm

RE: suggestion for improving raster loading

Tue Nov 21, 2006 1:13 pm

Hi,

Is it a new feature or does it exists for long time ?

I use GpsTools for 2 years and I decided 2 years ago to cut my MapLib in tiles.

Even now it is reallay faster when I cut my MapLib. So what is the internal tiles size used for the MapLib ?

Can we control this ?

I need a answer because I'm about to sole the problem of my cut when I zoom out.

Regards.

Guz.

Jonas
Posts: 2319
Joined: Mon Jan 09, 2006 2:20 pm
Location: Sweden

RE: suggestion for improving raster loading

Tue Nov 21, 2006 1:21 pm

This is an old feature, afaik, it has been around at least the past two years. Cutting the MapLib into smaller pieces is probably still faster since there will be less disc access if you don't have to seek around in the MapLib to get to the correct tiles. It's all a matter of simplicity and compactness over memory and speed.
The raster is cut to 256x256 tiles. This size will be customizeable in the next release (due for a beta any day now).

Regards,
Jonas
Franson Support

Guz
Posts: 47
Joined: Tue Sep 21, 2004 7:57 pm

RE: suggestion for improving raster loading

Tue Nov 21, 2006 2:03 pm

Great news !!!!

But for now I don't understand why it is faster then I cut my MapLib in many smaller ones and compute what is the MapLib to load (and then let GpsView manage internal tiles).

Can you confirm me that compute what tiles to draw is really slower then the MapLib becomes bigger ?

Regards.

Guz.

Guz
Posts: 47
Joined: Tue Sep 21, 2004 7:57 pm

RE: suggestion for improving raster loading

Tue Nov 21, 2006 2:47 pm

I think about this subject and I don't understand why moving the Map is really slower on big MapLib.

I was thinking that GpsView works on every pixel of the MapLib but you tols me that you manage tiles.

So can you explain me why it is slower, and is it possible to optimize this (index table ?) because for now I have to cut the MapLib and it produces trouble that I need to solve (as UnZoom).

Regards,

Guz.

Jonas
Posts: 2319
Joined: Mon Jan 09, 2006 2:20 pm
Location: Sweden

RE: suggestion for improving raster loading

Tue Nov 21, 2006 3:11 pm

As I said, it is slower because a larger MapLib means a larger file to read from. File access is slow on Pocket PC especially.
Also, a smaller MapLib means less chance of overlapping. If you hit a corner of a tile, it means that you have to read that tile plus the tiles that are close to it. The bottom-right corner of the first tile means that all the three bordering tiles needs to be loaded. This is (of course) also slowing down the process.

Regards,
Jonas
Franson Support

onesoftuk
Posts: 20
Joined: Fri Feb 29, 2008 4:24 pm
Location: United Kingdom

RE: suggestion for improving raster loading

Sun Aug 08, 2010 6:58 am

Please assist, i have been stuck with slow maps for years now, i have a very detailed OS map of the UK, i have made a single TIFF & world file and imported it to GpsTools, total size 196MB.

As this Maplib is so large panning is very slow. The only solution i can find is to use several MapLibs and change the active map based on a clicked position. But as stated here, i am left with a black corner if the clicked position is on the edge of the map.

Is there any way to paint the empty regions of the map with data from another MapLib?

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