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Subsections


5.2 Object Summary

The following table lists all of the objects (models of passive environmental objects) supported by Stage. They are described in detail in the following pages. See Section 5.3 for a list of Stage's devices.


Type Parent type Description

entity

None A generic entity, which has shape, exent and color - cannot be instantiated directly.

bitmap

entity A pattern of fixed obstacles loaded from a PNM bitmap file. Used to import building floorplans, walls, boulders, etc.

box

entity A fixed obstacle (can be moved by the user but not the robot).

puck

entity A movable object (can be moved by both the user and the robot).



5.2.1 The entity base type

Parent

<none>

Description

All Stage models are derived from the generic entity type. While this type can not be instantiated directly, all descendent types inherit its properties.

Properties

Name Values Description

name

string A descriptive name for this entity; used by the GUI.

pose

[x y a] Initialse pose (position and orientation).

shape

$\textstyle \parbox{30mm}{\verb'''rect''' \verb'''circle'''}$ Entity shape; entities can be either rectangular or circular.

size

[sizex sizey] Entity dimensions.
mass float mass for puck collision model; defaults to be immoveably massive.

color

string Descriptive color (e.g. "red" or "blue"); only colors listed in the X11 color database should be used (look for rgb.txt in your X installation).

fiducial_id

int The id returned by a fiducialfinder scanning this object. In the range 0-255, where 0 means the object will not be detected as a fiducial.

obstacle_return

$\textstyle \parbox{30mm}{\verb'''visible''' \verb'''invisible'''}$ Specifies whether or not this entity will be treated as a fixed obstacle for the purposes of collision detection. Derived types will set this to a sensible default.

sonar_return

$\textstyle \parbox{30mm}{\verb'''visible''' \verb'''invisible'''}$ Specifies whether or not this entity will be detected by sonar sensors. Derived types will set this to a sensible default.

vision_return

$\textstyle \parbox{30mm}{\verb'''visible''' \verb'''invisible'''}$ Specifies whether or not this entity will be seen by cameras; the color is specified by the color property. Derived types will set vision_return to a sensible default.

laser_return

$\textstyle \parbox{30mm}{\verb'''bright''' \verb'''visible''' \verb'''invisible'''}$ Specifies whether or not this entity will be seen be laser range finders; the "bright" value indicates that the entity is a retro-reflector (and hence produces a very intense return in the laser).

idar_return

$\textstyle \parbox{30mm}{\verb'''IDARTransparent''' \verb'''IDARReflect''' \verb'''IDARReceive'''}$ Specifies the behavior when hit by an IDAR beam.

interval

seconds Specifies the interval between model updates in seconds. Smaller intervals can increase simulation fidelity at cost of CPU time.

Defaults

Name Value
name ""
shape "none"
size [0 0]
pose [0 0 0]
color "black"
obstacle_return "invisible"
sonar_return "invisible"
vision_return "invisible"
laser_return "invisible"
gripper_return "invisible"
idar_return "IDARTransparent"
id -1
mass 1000.0
interval 0.1

5.2.2 The box object

Parent

entity

Description

The most simple object type, the box is used to create a rectangular or circular obstacle.

Properties

Name Values Description
<none>

Defaults

Name Value
shape "rect"
size [1.0 1.0]
color "yellow"
obstacle_return "visible"
sonar_return "visible"
vision_return "visible"
laser_return "visible"
idar_return "IDARReflect"

5.2.3 The bitmap object

Parent

entity

Description

The bitmap type is used to load a pattern of fixed obstacles (walls, rocks, trees, furniture, etc) defined in a PNM bitmap file. Since v1.3 a world file can specify as many bitmaps as desired, and bitmap respects the pose, color and most other properties.

Properties

Name Values Description

file

string The name of the image file describing the fixed obstacles; non-black image pixels will be treated as obstacles, black image pixels will be treated as empty space. Only pnm and gzipped pnm images are supported.

scale

float The image scale, in meters/pixel (or units-lengths/pixel if some another unit of length is specified).

Defaults

Name Value
color "black"
obstacle_return "visible"
sonar_return "visible"
vision_return "visible"
laser_return "visible"
idar_return "IDARReflect"
file ""
scale 0

Notes

Both the file and scale properties must be specified.

5.2.4 The puck object

Parent

entity

Description

The most simple object type, the box type is used to create a rectangular or circular obstacle.

Properties

Name Values Description
friction float Coefficient of friction for the puck sliding model.

Defaults

Name Value
shape "circle"
size [0.08 0.08]
color "green"
obstacle_return "visible"
vision_return "visible"
gripper_return "visible"
puck_return "visible"
friction 0.05
mass 0.2
interval 0.01

next up previous contents
Next: 5.3 Device Summary Up: 5. Entity Reference Previous: 5.1 Properties and the   Contents
2003-12-07