GIS application program

Discussion in 'Java' started by james, Jan 6, 2004.

  1. james

    james Guest

    I am developing a GIS java server and is now trying to write 2 modules
    one is about the algorithm to find the shortest route for a journey
    second one is the billing system used to support the billing service to
    count the number of bytes transferred in each process
    Do anyone have any reference and similar for my reference ..
    Thousands Thanx
     
    james, Jan 6, 2004
    #1
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  2. james

    Tim Ward Guest

    "james" <> wrote in message
    news:btev6i$t35$...
    > I am developing a GIS java server and is now trying to write 2 modules
    > one is about the algorithm to find the shortest route for a journey
    > second one is the billing system used to support the billing service to
    > count the number of bytes transferred in each process
    > Do anyone have any reference and similar for my reference ..
    > Thousands Thanx


    Shortest route (taking account, of course, of things like road type, speed
    limits, one way streets, traffic light delays, vehicle type (eg taxis can
    sometimes go places other cars can't), the real time feed from the traffic
    jam camera company, the slightly less real time feed from the roadworks
    database, time of day/week (for streets that are closed at some times of
    day/week), weather) is an *extremely* complex calculation. This is just one
    small reason why useful GIS and traffic modelling systems are expensive.
    It's not something you can knock up in Java in an afternoon.

    --
    Tim Ward
    Brett Ward Limited - www.brettward.co.uk
     
    Tim Ward, Jan 7, 2004
    #2
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  3. james

    Sudsy Guest

    Tim Ward wrote:
    <snip>
    > Shortest route (taking account, of course, of things like road type, speed
    > limits, one way streets, traffic light delays, vehicle type (eg taxis can
    > sometimes go places other cars can't), the real time feed from the traffic
    > jam camera company, the slightly less real time feed from the roadworks
    > database, time of day/week (for streets that are closed at some times of
    > day/week), weather) is an *extremely* complex calculation. This is just one
    > small reason why useful GIS and traffic modelling systems are expensive.
    > It's not something you can knock up in Java in an afternoon.


    Add to that the need to route around accidents, construction sites, etc.
    and you can see why a dispatch system for 911 (for example) is a huge
    undertaking. Having worked on one, I can assure you that Tim's comments
    are spot-on!
     
    Sudsy, Jan 7, 2004
    #3
  4. james

    james Guest

    I know this is a huge project. So I am not trying to complicate the things.
    I may just consider the shortest path and road traffic and will not take
    into account too much of the data. Can anyone give me some reference to
    start with ??? I am planning to do it in months time

    "Sudsy" <> ??? news:
    ???...
    > Tim Ward wrote:
    > <snip>
    > > Shortest route (taking account, of course, of things like road type,

    speed
    > > limits, one way streets, traffic light delays, vehicle type (eg taxis

    can
    > > sometimes go places other cars can't), the real time feed from the

    traffic
    > > jam camera company, the slightly less real time feed from the roadworks
    > > database, time of day/week (for streets that are closed at some times of
    > > day/week), weather) is an *extremely* complex calculation. This is just

    one
    > > small reason why useful GIS and traffic modelling systems are expensive.
    > > It's not something you can knock up in Java in an afternoon.

    >
    > Add to that the need to route around accidents, construction sites, etc.
    > and you can see why a dispatch system for 911 (for example) is a huge
    > undertaking. Having worked on one, I can assure you that Tim's comments
    > are spot-on!
    >
     
    james, Jan 7, 2004
    #4
  5. Even the most simple things will not be simple.


    Take point A and point B and construct a vector between the two points.
    Create a list of all roads that this vector crosses.

    Use intersecting roads in the list to break each of the other roads in the
    list into smaller subsections and place these subsections in the list while
    removing the larger road objects.

    Sort the list of road subsections according to whichever endpoint is nearest
    to point A.

    Search an ever exanding radius around point A and point B until you find the
    nearest adjacent road.

    Find the road subsection in the list which intersect the adjacent road, or
    find the adjacent road in the list.

    Connect the dots of each endpoint traversing each subsection of road until
    you reach point B from point A.

    This may or may not be the shortest distance or time, but this will give you
    a start from which you can
    expand a search radius from each subsection of road to the next parallel or
    adjacent road to check for
    speed limits, traffic signals etc.

    This overview should get you started.

    Eugene...


    "james" <> wrote in message
    news:bthajk$36u$...
    > I know this is a huge project. So I am not trying to complicate the

    things.
    > I may just consider the shortest path and road traffic and will not take
    > into account too much of the data. Can anyone give me some reference to
    > start with ??? I am planning to do it in months time
    >
    > "Sudsy" <> ??? news:
    > ???...
    > > Tim Ward wrote:
    > > <snip>
    > > > Shortest route (taking account, of course, of things like road type,

    > speed
    > > > limits, one way streets, traffic light delays, vehicle type (eg taxis

    > can
    > > > sometimes go places other cars can't), the real time feed from the

    > traffic
    > > > jam camera company, the slightly less real time feed from the

    roadworks
    > > > database, time of day/week (for streets that are closed at some times

    of
    > > > day/week), weather) is an *extremely* complex calculation. This is

    just
    > one
    > > > small reason why useful GIS and traffic modelling systems are

    expensive.
    > > > It's not something you can knock up in Java in an afternoon.

    > >
    > > Add to that the need to route around accidents, construction sites, etc.
    > > and you can see why a dispatch system for 911 (for example) is a huge
    > > undertaking. Having worked on one, I can assure you that Tim's comments
    > > are spot-on!
    > >

    >
    >
     
    Eugene Staten, Jan 8, 2004
    #5
  6. james

    Chris Gokey Guest

    Two common algorithms used for this type of thing is Dijkstra's Algorithm
    and Bellman Ford. I did something in graduate school to calculate the
    shortest route given the fact that some routes vary is cost. There is some
    algorithms written in Java that might help you out:

    http://home.comcast.net/~cgokey/java/network/

    There is an applet that you can run where you can draw a simple map and it
    will calculate the shortest route.

    Chris

    Eugene Staten wrote:

    > Even the most simple things will not be simple.
    >
    >
    > Take point A and point B and construct a vector between the two points.
    > Create a list of all roads that this vector crosses.
    >
    > Use intersecting roads in the list to break each of the other roads in the
    > list into smaller subsections and place these subsections in the list
    > while removing the larger road objects.
    >
    > Sort the list of road subsections according to whichever endpoint is
    > nearest to point A.
    >
    > Search an ever exanding radius around point A and point B until you find
    > the nearest adjacent road.
    >
    > Find the road subsection in the list which intersect the adjacent road, or
    > find the adjacent road in the list.
    >
    > Connect the dots of each endpoint traversing each subsection of road until
    > you reach point B from point A.
    >
    > This may or may not be the shortest distance or time, but this will give
    > you a start from which you can
    > expand a search radius from each subsection of road to the next parallel
    > or adjacent road to check for
    > speed limits, traffic signals etc.
    >
    > This overview should get you started.
    >
    > Eugene...
    >
    >
    > "james" <> wrote in message
    > news:bthajk$36u$...
    >> I know this is a huge project. So I am not trying to complicate the

    > things.
    >> I may just consider the shortest path and road traffic and will not take
    >> into account too much of the data. Can anyone give me some reference to
    >> start with ??? I am planning to do it in months time
    >>
    >> "Sudsy" <> ??? news:
    >> ???...
    >> > Tim Ward wrote:
    >> > <snip>
    >> > > Shortest route (taking account, of course, of things like road type,

    >> speed
    >> > > limits, one way streets, traffic light delays, vehicle type (eg taxis

    >> can
    >> > > sometimes go places other cars can't), the real time feed from the

    >> traffic
    >> > > jam camera company, the slightly less real time feed from the

    > roadworks
    >> > > database, time of day/week (for streets that are closed at some times

    > of
    >> > > day/week), weather) is an *extremely* complex calculation. This is

    > just
    >> one
    >> > > small reason why useful GIS and traffic modelling systems are

    > expensive.
    >> > > It's not something you can knock up in Java in an afternoon.
    >> >
    >> > Add to that the need to route around accidents, construction sites,
    >> > etc. and you can see why a dispatch system for 911 (for example) is a
    >> > huge undertaking. Having worked on one, I can assure you that Tim's
    >> > comments are spot-on!
    >> >

    >>
    >>


    --
     
    Chris Gokey, Jan 8, 2004
    #6
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