AAAAaaaaaagh!!!

Any Ideas:

I have to produce a guidance system from one location to the next using Filemaker for my University project. Any ideas on how I could get Filemaker to direct from one reference point to the next "on the fly" using Scripts?

I am at a loss!

Cheers

James

Forget about scripts until you have thought about and organized your data first.

What data do you have? What data will the user input? What data to you need to present to the user?

Okay heres the basic idea behind the project: A businessman is in Florence, Italy with a Palm Vx handheld. He is lost and needs to find the Bar Rotunda. By logging onto the internet on a wireless connection he can enter where he is via a landmark, street name etc. and then enter where about he needs to be.

Once this is done the data is processed by Filemaker returning guidance directions.

I have a 16x16 sub-sectioned map of Florence which I intended to scan into GIF format. These small maps could then be presented on the screen showing where the user is, and where he needs to be. I presume that I will need some sort of cross-reference location facility to locate the user/amenity on the map, and then some sort of algorith to "link" the starting point with the destination.

At the moment I have a database filled with Amenity information such as price, goods offered etc.

I am in the process of scanning the maps in to a new Filemaker database which will be linked to the original.

I hope this is a bit clearer, thanks for your reply

James

It sounds to me you need a database, whose records are every landmark, street, etc plus a grid reference. This is just a lot of work, not technically hard.

The tricky part is the algorithm that works out how to get from *here* to *there*. Tricky because it would have top take into account routes and shortcuts etc (eg, the most direct route -- and easiest to program for -- might be a straight line but there just could be a river or lake in the way that requires navigating around).

For a project like this, I'd start SMALL, really small, and get a basic concept working first.

And get the client to pay by the hour...

This sounds like classic graph theory, and I don't mean piecharts. You basically have a bunch of nodes (intersections) and links (the short stretch of road between each intersection). you can build a map by creating a record for each link. You have 3 fields:

LinkID, StartNode and EndNode. You will probably want a 4th field LinkLength which will be the length of the link. This lets you calculate a total distance between two end points. Start with a small set of data like this:

A---B---C---D

| | | |

E---F---G---H This doesn't line up

| | | |

J---K---L---M vertically unless you view it

| | | |

P---Q---S---T with a monospaced font

Note that you can go from point B to point C and also from point C back to point B (unless this is a one way street). So, your data would look (assuming the length of all blocks is 100) like:

LinkID, StartNode, EndNode, LinkLength

1,A,B,100

2,A,E,100

3,B,A,100

4,B,C,100

5,B,F,100

7,6,C,B,100

8,C,D,100

9,C,G,100

etc.

A separate file could store important landmarks like:

LandmarkID, Name, LinkID, StreetSide, Distance

1, "Murphy's Pub", 5, East, 60

This would indicate that Murphy's pub is on the east side of the street, on link 5 (between point B and F) 60 feet from point B.

Suppose you are at point M and you want to get to Murphy's pub. You need the script to put together a list of connected links to get there: M-L, L-K, K-F, F-B. This is the interesting part. There is a lot of theory on this subject, and a number of algorithms to find the shortest distance between two points on a map without getting into and endless loop. You can do it with Filemaker, although it is usually done in a programming language like C. Find a book on the subject and start reading.

[This message has been edited by BobWeaver (edited February 10, 2001).]