[Routing] monav preprocessing 32bits vs 64bits OS

[VeaaC FDIRCT]

Hi,

On Thu, Aug 26, 2010 at 4:32 PM, Quach Minh <quachhoangminh at gmail.com> wrote:
> You indicated that the preprocessing of Europe needs 10GB RAM --> 64bits OS
> is required.
>
> Is it trivial to move from 32bits to  64bits OS? Is your data structure
> designed to work on both platforms?

That depends on the software and OS you are using. I can only speak
for MoNav itself:
 - You need all dependencies in 64Bit. That may require you to compile
some yourself, e.g., most binary packages for Windows are 32Bit.
 - MoNav itself compiles fine for 32Bit and 64Bit, in fact I have
tested it myself on: Xubuntu 32Bit + 64Bit, ArchLinux 64, Windows XP +
Vista + 7 ( 32 Bit ), Windows Mobile ( 32 Bit ), Windows XP + Vista +
7 ( 32 Bit WoW64 ).

> Is it easy if I want to add some
> features to the data?

That depends what kind of data you want to add and what plugin you
want to add it to. Most plugins use a compression scheme to retrieve
data efficiently on mobile devices. You would have to add your data to
those compression schemes, but you could start with simply writing /
reading your data uncompressed. This means its quite easy to add
custom data to the GPSGrid, UnicodeTournamentTrie and Renderer
plugins.

It gets a little bit more complicated if you want to change the data
the ContractionHierarchies routing plugin returns. Not only do you
have to add your data to the edges and nodes as well as to their
compression schemes, but you have to incorporate it into the
"pre-unpacked shortcuts". This requires some insight in how the
algorithm works:
Essentially a shortcut represents a path and its complete path
description is stored explicitly. Things get a little bit more
complicated because the shortcuts' unpacked paths can be nested and
reversed to save storage space. Nevertheless the overall amount of
work to add custom data should not be too high. If you want to add
data to the routing plugin I would strongly advise you to use the (
slightly unstable ) SVN version instead of the 0.1 release as the
compressed graph data structure has been completely redesigned and
simplified.

If you are encountering some problems while adding your custom data,
I'd be happy to assist.

Greeting

Christian Vetter