Minimal Memory Abstractions

Transcription

1 Miniml Memory Astrtions (As implemented for BioWre Corp ) Nthn Sturtevnt University of Alert GAMES Group Ferury, 7 Tlk Overview Prt I: Building Astrtions Minimizing memory requirements Performnes mesures Prt II: BioWre Corp Implementtion Experiene

2 Bkground Stte-spe strtions hve ommonly een used to speed serh Pttern Dtses for heuristis Grph strtions for pthfinding PRA*, HPA*, et Motivtion Gmes hve tight memory udgets ~4MB totl memory 4x4 or lrger mps MB per yte per grid ell Cn we use uild n strtion whih minimizes memory usge? 4

3 Assumptions Grid world No true -d movement Cells n e loked/free/weighted My e height differene etween ells Units n move ross rel-vlued spe 5 Setors / Regions Divide world into lrge setors Fixed size Index impliitly Divide setors into regions Regions entirely onneted Regions hve enter point 6

4 Setors / Regions Divide world into lrge setors Fixed size Index impliitly Divide setors into regions Regions entirely onneted Regions hve enter point 6 Setors / Regions Divide world into lrge setors Fixed size Index impliitly Divide setors into regions Regions entirely onneted Regions hve enter point 6

5 Edges Look t orders of regions to determine edges 7 Edges Look t orders of regions to determine edges 7

6 Edges Look t orders of regions to determine edges 7 Edges Look t orders of regions to determine edges 7

7 Edges Look t orders of regions to determine edges 7 Edges Look t orders of regions to determine edges 7

8 Astrt Grph Originl Mp: x = 4 ells Astrt Grph: 9 nodes edges 8 its per setor Cn use less its Memory Usge 8 its per edge its - diretion 5 its - region Skip some regions Edges duplited 6 its 6 its per region Setor Dt # Regions Exmple Memory Address unused - Region Dt enter # edges enter # edges Exmple left: upleft: up: up: up: vrile-sized edge storge 9

9 Find Setor/Region Begin with x/y lotion in rel world Must find setor/region If setor only hs region, done Otherwise do BFS to find region enter Cn do reverse A* serh from region enters Avoids pointers! Usge () Find setor/region for strts nd gols Use A* to find omplete strt pth Now we must use the strt pth to guide the serh for n tul pth

10 Usge () Mny different methods for using strt pth Simplest method: Find pth from strt to first region Compute pth to suessive regions Find pth from lst region to gol Usge Exmple Find strt prents Find strt pth Find rel pth

11 Usge Exmple Find strt prents Find strt pth Find rel pth Usge Exmple Find strt prents Find strt pth Find rel pth

12 Usge Exmple Find strt prents Find strt pth Find rel pth Usge Exmple Find strt prents Find strt pth Find rel pth

13 Usge Exmple Find strt prents Find strt pth Find rel pth Totl Pthfinding Cost Astrt plnning ost + Refinement Refinement ost depends on ostles nd totl pth length Astrt plnning ost depends on setor size For fixed pth length, the totl work should depend only on setor size 4

14 Optimizing Region Centers How to determine the region enters? Some lotions re muh etter thn others 5 Optimizing Region Centers 6

15 Optimizing Region Centers 7 Optimizing Region Centers Consider eh region independently Mesure the A* ost to pth etween region nd ll neighors Choose the region enter whih minimizes the mximum ost 8

16 Pthfinding Optimiztion Refinement t strt/ gol n e ineffiient Trimming helps S G Skip to next node t strt/gol 9 Pthfinding Optimiztion Refinement t strt/ gol n e ineffiient Trimming helps S G Skip to next node t strt/gol 9

17 Pthfinding Optimiztion Refinement t strt/ gol n e ineffiient Trimming helps S G Skip to next node t strt/gol 9 Pthfinding Optimiztion Refinement t strt/ gol n e ineffiient Trimming helps S G Skip to next node t strt/gol 9

18 Pthfinding Optimiztion Refinement t strt/ gol n e ineffiient Trimming helps S G Skip to next node t strt/gol 9 Experimentl Results 9, pths over mps Mps sled to 5x5 Pths in 8 ukets length 5 Mesure: Totl ost Inrementl ost

19 Memory Usge How does the memory usge sle with setor size? How muh memory n e sved with simple ompression? Don t store defult regions region, 8 neighors Memory Usge Mps Size 5x5 Totl Memory (KB) Setor Size

20 Dynmi Region Centers Is there gin to dynmilly optimizing region enters? Mesure 95% work done in one-step pth refinement Dynmi Centers Dynmi v. Stti Centers (-Step Plnning) 5 Stti (95th perentile) Dynmi (95th perentile) Nodes Expnded Setor Size 4

21 Optimlity Pths will not e optiml Speil ses for strt/gol help lot Smoothing will e pplied s postproessing step (not mesured) 5 Optimlity Optimlity 5 95% Averge 5% % Suoptiml Setor Size 6

22 Totl Work Sum of work needed: Find prents Find strt pth Refine low-level pth Compre to A* 7 Totl Work Totl Nodes Expnded 5 Setor Size Setor Size Buket (Pth Length/4) 8

23 Totl Work v. A* Svings Over A* Totl Nodes Expnded Mx (A*) Averge (A*) Mx (MM) Averge (MM) Minimum Buket (Pth Length/4) 9 Drgon Age BioWre Corp Due Winter 7/8

24 Drgon Age BioWre Corp Due Winter 7/8 Implementtion weeks: Implement strtion Implement pthfinding Initil testing Met pthfinding requirements

25 Oservtions Cnnot e n expert in one thing Get it good enough Both more nd less rigorous testing thn expeted Gret people Future Continuing work: Smoothing Pleles 4

26 More Info Thnks 6