Persistent Realtim E Building Interior Generation

P ersistent R ealtim e Building Interior
G eneration

By
Evan Hahn

A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfilment of the requirements for the degree of
Master of Computer Science

Ottawa-Carleton Institute for Computer Science
School of Computer Science
Carleton University Ottawa, Ontario

September 2006
© Copyright
2006, Evan Hahn

Reproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission.

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Abstract

We present a novel approach to generate virtual building interiors in realtime. The interiors are generated in a top-down fashion using architectural guidelines. Although a building interior in its entirety may be quite large, only the portions that are needed immediately are generated. This lazy generation scheme allows the use of only a fraction of the memory that a model of the entire interior would take. Our method provides realtime frame rates, making it attractive for interactive applications such as videogames and simulators.
Memory is controlled by deleting regions of the interior that are no longer needed.
Any changes made in these regions is not lost as we provide a simple and efficient method to allow changes made to the interior to persist past the lifetime of the regions that contain them. This allows a dynamic, consistent environment and increases control over the content by allowing developers to make changes.

Contents

4 5 5 6

1.1 M o tivation ............................................................................................................

1.2 Scope ...................................................................................................................

1.3 C o n tributions .....................................................................................................

1.4 Thesis O verview ..................................................................................................

2.1 P rocedural Geometry S y n th e sis ....................................................................

2.2 G enerating A rc h ite ctu re .................................................................................

2.3 P ersistence ............................................................................................................

17 19 23 24 25 25 26 27 27 30 36

3.1 Lazy Generation ...............................................................................................

3.2 G eneration R u le s ...............................................................................................

3.3 Temporary Region T y pes .................................................................................

3.4 Portal Types .....................................................................................................

3.5 Building Setup ..................................................................................................

3.5.1 Texture S e lection ..................................................................................

3.5.2 Elevator Shaft Creation ....................................................................

3.6 Floor D ivision ......................................................................................................

3.7 Hallway D iv i s io n ...............................................................................................

3.7.1 Portal P l a cem en t ..................................................................................

3.7.2 Hall S egm ents ........................................................................................

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission.

3.7.3 Hall L o ops ..............................................................................................

3.8 Room Cluster D iv isio n ....................................................................................

3.9 Built Region Creation ....................................................................................

3.10 O bject P lacem ent ..............................................................................................

3.11 R andom Number G eneration ..........................................................................

3.12 G raphical Sum m ary ...........................................................................................

38 40 43 45 46 48

56 58 59

4.1 The Generation T r e e .......................................................................................

4.2 C a c h i n g ...............................................................................................................

4.3 Deleting R e g io n s ..............................................................................................

62 62 63 63 63 64 65 66 66

5.1 R e c o r d s ..............................................................................................................

5.2 Removal T im e ....................................................................................................

5.3 Types of C h a n g e ..............................................................................................

5.3.1 Face Appearance C h a n g e s ................................................................

5.3.2 Non-Generated Object C h an g es ......................................................

5.3.3 G enerated Object C hanges ................................................................

5.3.4 Portal C h a n g e s ....................................................................................

5.4 Objects Occupying multiple r e g io n s ............................................................

5.5 D iscussion ...........................................................................................................

7.0.1 Future W ork ..........................................................................................

79 80 81

A .l Collision D e te c tio n ..........................................................................................

A.2 Point Location .................................................................................................

A.3 V isibility ..............................................................................................................

Bibliography

List of Tables

3.1 Legend of Region Types iv

List of Figures

1.1 Left: A screen shot showing a building’s first person view and its generated contents. Right: A wireframe view of the same building generated

completely.......................................................................................

3
3.1 An example generating a section of a building around a point............... 3.2 An example floor with a large portion of dead space................................. 3.3 An example floor demonstrating the proper widths for room clusters. 3.4 A side view of a lazy generated building showing the floor divisions

necessary to create a single floor.....................................................................

3.5 An example division around the hall region................................................. 3.6 An example Hall Segment portal placement using our hallway portal
18 21 22

placing convention........................................................................

3.7 An example series of portal placements...................................
31 32
3.8 An example demonstrating portal placement when Hallway portals are

found directly across from the hall region....................................................

33
3.9 An example showing the possible remaining edges to place portals along. 36 3.10 Example of the steps taken to create a hall loop....................................... 3.11 A section of a building containing two hall loops...................................... 3.12 An example extending the hall loop so that every hall portal can be

directly across from on of its edges ............................................................

3.14 A Building region generates a Floor Divide region and an Elevator

Shaft region....................................................................................

3.15 A Floor Divide region splits into smaller Floor Divide regions or be-

comes a Hall Divide region ..........................................................................

3.16 A Hall Divide region splits around either a Hall Segment or a Hall

Loop region......................................................................................................

3.17 A Hall Loop region divides into a middle region surrounded by Hall

Segment regions.............................................................................................

3.18 A Room Cluster Divide region either splits into two smaller Room Clus-

ter Divide regions or becomes a built region.........................................

3.19 A Hall Segment region becomes a built region.................................... 3.20 An Elevator Shaft region becomes a built region................................

3.21 Elevator portals are placed between Elevator Shaft and Floor Divide

regions..............................................................................................................

3.22 Hallway portals are normally placed between hall and Hall Divide regions, or two Hall Divide Regions. There is also a situation where Hallway portals are placed between hall and Room Cluster regions. This occurs when an existing Hallway portal is found directly across a

hall region over a Room Cluster re g io n ................................................

3.23 Room Door portals are placed between hall and Room Cluster regions, hall and Hall Divide regions, or two Hall Divide regions...................

3.24 A generation example from our im plem en tatio n ..............................

3.25 The generation example continued.........................................................

49
49 50 50 50 51

52 52 54 55

4.1 A small generation tree...............................................................................

6.2 The polygon count of a complete building vs the number of regions in

a complete building.....................................................................................

6.3 The average time taken to generate around a point vs the number of

regions in a complete b u ild in g .................................................................

Persistent Realtim E Building Interior Generation

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