1. 27.02.2003Generating Directions1 Lecture 2 Map Data Path Based Plan

2. 27.02.2003Generating Directions2 Before we start NDA mdina.zip (for a few days)

3. 27.02.2003Generating Directions3 Proposed Architecture GIS Map Query Path Planner Sentence Plan Message Based Plan Path Based Plan Text PlannerSentence Planner Text Realisation

4. 27.02.2003Generating Directions4 Map Data Files These exist 3 data files with tab separated data inside them. These files describe –Buildings –Routes (ie streets) –Way points: points on streets Minor errors in data (St. names)

5. 27.02.2003Generating Directions5 Buildings Example: MDINA 1 TRIQ VILLEGAIGNON 0 MDINA DUNGEON O 35.845252 14.369577 Attributes in order –Location: char(32) –Building ID: int –Street Prefix: char(15) –Street Name: char(80) –Building Number: int –Building Name: char(10) –Building Proper Name: char (80) –Building Type: char(1) C:commercial, O: other –X coord and y coord:float

6. 27.02.2003Generating Directions6 Routes Example: MDINA1 SQAQ ARAGONA RBT 12 Attributes in this order: –Location: char(32) –Route ID: int –Street Prefix:char(15) –Street Name:char(80) –Postcode:char(8)

7. 27.02.2003Generating Directions7 Routes Way Points Examples 1MDINA 1 SQAQ ARAGONARBT 1235.766601 14.399467 2MDINA 1 SQAQ ARAGONARBT 1235.770655 14.401142 Attributes in order –Way Point ID: number –Location: char(32) –Route ID: number –Street Prefix: char (15) –Street Name: char(80) –Postcode: char(8) –X coord and Y coord:float

8. 27.02.2003Generating Directions8 Summary Route way points give you enough description of intersections and roads ‘Buildings’ files gives you info on which road they reside, just missing route id Thus it is possible to build description of buildings when traversing route. A subtask will be to build your system to describe buildings while going through just one road

9. 27.02.2003Generating Directions9 Search Problem Given start and goal positions, compute path-based plan. State-based search –start node –end node –operators –search strategy

10. 27.02.2003Generating Directions10 Start and End Nodes Can be specified in any reasonable way e.g. –Coordinates –Building –Point of intersection –Waypoint

11. 27.02.2003Generating Directions11 Operators Operator = state to state transformation Consider each operator to be a path between adjacent points of intersection. Operator data structure minimally contains start and end points. Later details of journey can be added (buildings etc.)

12. 27.02.2003Generating Directions12 Method Define classes: point; path; plan.... Compute all intersection points from map data. Compute set of "operators" (paths) = journeys between adjacent intersection points Find intersection points nearest start and goal. Search for spanning path using paths between intersection points.

13. 27.02.2003Generating Directions13 Search Algorithm which checks which road to go through to arrive from point A to point B. You will need appropriate algorithms or data structures for intersections. Start off using brute force search. Watch out for infinite recursions! This should give you a route through a series of route ids. See Russell & Norvig (2003) for details of search algorithms.

14. 27.02.2003Generating Directions14 Taken from Russell & Norvig 2003

15. 27.02.2003Generating Directions15 Next Elaboration of Path-Based Plan Path-Based Plan => Message Based Plan.