Geodatabase tables

[Steve Pashby]

Ken Lord <kenlord <at> GMAIL.COM> writes:

> 
> Hi Steve, Frank,
> 
> Steve, If i understand it correctly, you have a route event feature
> class in your personal geodatabase that you want to display in
> MapServer, a product of some linear referencing work.
> 
> Please correct me if I'm wrong, but you are probably setup so that:
> 
> - you have a feature class made up of lines, your roads, which define
> a route. These lines have a route ID to identify the route, and
> another attribute which defines the order in which the road lines make
> up the route from start to finish.
> - you have an event table defining points or lengths along the line
> with associated attributes, such as 'a crash happened here', 'speed
> limit on this section', etc.  This table also has a Route ID that
> matches the appropriate route in the feature class. This non-spatial
> table has a Measure attribute that describes how far along the route
> the event is if its a point, or 2 measure attributes with its start
> and finish distances along the route if its a segment.
> 
> ... And you would like to show these events located correctly along
> your roads in MapServer, from a personal geodatabase.
> 
> ArcIMS (sorry to say that evil word) displays route events from
> personal geodatabases without any problem.
> 
> Aside from having Frank wave his magical coding wand,  I would suggest
> that you look into the linear referencing functions in PostGIS 1.1.1.
> however the spatial SQL in your DATA string may get out a bit out of
> hand and slow down the generation of your maps.
> 
> To keep the 'on-the-fly' processing to a minimum, once you have your
> route events created, you might want to just convert them into actual
> point / line features, regardless of the format used to hold the data.
> 
> Cheers,
> Ken Lord
> Vancouver BC
> 
> On 4/5/06, Frank Warmerdam <warmerdam <at> pobox.com> wrote:
> > Steve Pashby wrote:
> > > 
 ==============================================================================
> > > Thanks very much for the reply Frank.  However, my tables are not 
specifically
> > > spatial tables (holding x,y coords), but rather they have a unique field
> > > (Route_ID) that is a link to a shapefile (containing road centre-line 
data)
> > > and each road has its own unique Route-ID. This is (i think) what links 
the
> > > two together.
> >
> > Steve,
> >
> > I have never seen a personal geodatabase setup like this.  If you make it
> > available to me I might have a look.
> >
> > When you speak of a "personal geodatabase", you do specifically mean this
> > in the ESRI ArcGIS sense, right?
> >
> > It might also make sense for you to access the database via a plain ODBC
> > connection to get the data out rather than having OGR treat it as a
> > personal geodatabase.
> >
> > Best regards,
> > --
> > ---------------------------------------+-----------------------------------
---
> > I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam <at> 
pobox.com
> > light and sound - activate the windows | http://pobox.com/~warmerdam
> > and watch the world go round - Rush    | President OSGF, http://osgeo.org
> >
> 
> 
G'day, 

Thankyou so much for all the help.  I'm still in the early planning stage of 
this project and at this point have not set up the geodatabase - as i don't 
want to spend ages setting it up only to find out it won't work !  Ken Lords 
response hit the nail on the head, and it is being done in ERSI ArcGIS 9.0, 
using a Personal Geodatabase (which to my limited understanding is not the 
same as using SDE and Oracle - this is termed a multi-user geodatabase and has 
a lot more functionality as the size is unlimited.  The Personal Geodatabase 
is limited to 2Gb in size and simply uses Microsoft Access tables without 
having to go through SDE.)

My initial designs were to have a personal geodatabase in the C: drive 
called "Corporate_Roads.mdb", and then to have a feature dataset 
called "Roads", from this i would have a feature class 
called "Road_Centre_line" (Line type) containing a Route_ID, and a road name 
attribute.  Then i would have another feature class called "Surface_Condition" 
(a table) with the Route_ID (which links it back to the feature class 
Road_Centre_Line), Condition_Rating (a rating from 0-6), From_Measure (giving 
the start linear distance - starts a zero and increases), and a To_Measure 
(giving the finish linear distance).  

I hope you can make sense of this !

Many thanks.

Steve