tdw_physics

These classes create a generic structure for generating physics datasets using TDW. They aim to:

Simplify the process of writing many similar controllers.
Ensure uniform output data organization across similar controllers.

Requirements

TDW (See requirements for graphics rendering)
Some controllers in this repo have additional requirements. Read this for a more detailed list.

Installation

cd path/to/tdw_physics
pip3 install -e . (This installs the tdw_physics module).

Controllers

See the controllers/ directory for controllers that use tdw_physics as well as documentation. See below for the output .hdf5 file structure.

Changelog

See changelog.

Usage

tdw_physics provides abstract Controller classes. To write your own physics dataset controller, you should create a superclass of the appropriate controller.

Abstract Controller	Output Data
`RigidbodiesDataset`	`Tranforms`, `Images`, `CameraMatrices`, `Rigidbodies`, `Collision`, `EnvironmentCollision`
`TransformsDataset`	`Transforms`, `Images`, `CameraMatrices`
`FlexDataset`	`Transforms`, `Images`, `CameraMatrics`, `FlexParticles`

Every tdw_physics controller will do the following:

When a dataset controller is initially launched, it will always sent these commands.
Initialize a scene (these commands get sent only once in the entire dataset).
Run a series of trials:
1. Initialize the trial.
2. Create a new .hdf5 output file.
3. Write static data to the .hdf5 file. This data won't change between frames.
4. Step through frames. Write per-frame data to the .hdf5 file. Check if the trial is done.
5. When the trial is done, destroy all objects and close the .hdf5 file.

Each trial outputs a separate .hdf5 file in the root output directory. The files are named sequentially, e.g.:

root/
....0000.hdf5
....0001.hdf1

All images are 256x256
The _img pass is a .jpg and all other passes are .png

How to Create a Dataset Controller

Regardless of which abstract controller you use, you must override the following functions:

Function	Type	Return
`get_scene_initialization_commands()`	`List[dict]`	A list of commands to initialize the dataset's scene. These commands are sent only once in the entire dataset run (e.g. post-processing commands).
`get_trial_initialization_commands()`	`List[dict]`	A list of commands to initialize a single trial. This should include all object setup, avatar position and camera rotation, etc. You do not need to include any cleanup commands such as `destroy_object`; that is handled automatically elsewhere. NOTE: You must use alternate functions to add objects; see below.
`get_per_frame_commands(resp: List[bytes], frame: int):`	`List[dict]`	Commands to send per-frame, based on the response from the build.
`get_field_of_view()`	`float`	The avatar's field of view value.

`RigidbodiesDataset`

from typing import List
from tdw_physics.rigidbodies_dataset import RigidbodiesDataset

class MyDataset(RigidbodiesDataset):
    def get_scene_initialization_commands(self) -> List[dict]:
        # Your code here.

    def get_trial_initialization_commands(self) -> List[dict]:
        # Your code here.

    def get_per_frame_commands(self, resp: List[bytes], frame: int) -> List[dict]:
        # Your code here.

    def get_field_of_view(self) -> float:
        # Your code here.

A dataset creator that receives and writes per frame: Tranforms, Images, CameraMatrices, Rigidbodies, Collision, and EnvironmentCollision.

Ending a trial

A RigidbodiesDataset trial ends when all objects are "sleeping" i.e. non-moving, or after 1000 frames. Objects that have fallen below the scene's floor (y < -1) are ignored.

You can override this by adding the function def is_done():

    def is_done(self, resp: List[bytes], frame: int) -> bool:
        return frame > 1000 # End after 1000 frames even if objects are still moving.

Adding objects

Objects should only be added in get_trial_initialization_commands() or (more rarely) get_per_frame_commands().

`def get_add_physics_object()`

Get commands to add an object and assign physics properties. Write the object's static info to the .hdf5 file.

Return: A list of commands to add an object and set its physics values.

from typing import List
from tdw_physics.rigidbodies_dataset import RigidbodiesDataset

class MyDataset(RigidbodiesDataset):
    def get_trial_initialization_commands(self) -> List[dict]:
        commands = []
        # Your code here.
        object_id = self.get_unique_id()
        commands.extend(self.get_add_physics_object(model_name="iron_box",
                                                    library="models_core.json",
                                                    object_id=object_id,
                                                    position={"x": 0, "y": 0, "z": 0},
                                                    rotation={"x": 0, "y": 0, "z": 0},
                                                    default_physics_values=False,
                                                    mass=1.5,
                                                    dynamic_friction=0.1,
                                                    static_friction=0.2,
                                                    bounciness=0.5))
        return commands

Parameter	Type	Default	Description
model_name	str		The name of the model.
position	Dict[str, float]	None	The position of the model. If None, defaults to `{"x": 0, "y": 0, "z": 0}`.
rotation	Dict[str, float]	None	The starting rotation of the model, in Euler angles. If None, defaults to `{"x": 0, "y": 0, "z": 0}`.
library	str	""	The path to the records file. If left empty, the default library will be selected. See `ModelLibrarian.get_library_filenames()` and `ModelLibrarian.get_default_library()`.
object_id	int		The ID of the new object.
scale_factor	Dict[str, float]	None	The scale factor.
kinematic	bool	False	If True, the object will be kinematic.
gravity	bool	True	If True, the object won't respond to gravity.
default_physics_values	bool	True	If True, use default physics values. Not all objects have default physics values. To determine if object does: `has_default_physics_values = model_name in DEFAULT_OBJECT_AUDIO_STATIC_DATA`.
mass	float	1	The mass of the object. Ignored if `default_physics_values == True`.
dynamic_friction	float	0.3	The dynamic friction of the object. Ignored if `default_physics_values == True`.
static_friction	float	0.3	The static friction of the object. Ignored if `default_physics_values == True`.
bounciness	float	0.7	The bounciness of the object. Ignored if `default_physics_values == True`.

`def get_objects_by_mass()`

Return: IDs of objects with mass <= the mass threshold.

Parameter	Type	Default	Description
`mass`	`float`		The mass threshold.

`def get_falling_commands()`

Return: A list of lists; per-frame commands to make small objects fly up.

Parameter	Type	Default	Description
`mass`	`float`	3	Objects with <= this mass might receive a force.

`PHYSICS_INFO`

RigidbodiesDataset caches default physics info per object (see above) in a dictionary where the key is the model name and the values is a PhysicsInfo object:

from tdw_physics.physics_info import PHYSICS_INFO

info = PHYSICS_INFO["chair_billiani_doll"]

print(info.model_name) # chair_billiani_doll
print(info.library)
print(info.mass)
print(info.dynamic_friction)
print(info.static_friction)
print(info.bounciness)

.hdf5 file structure

static/    # Data that doesn't change per frame.
....object_ids
....mass
....static_friction
....dynamic_friction
....bounciness
frames/    # Per-frame data.
....0000/    # The frame number.
........images/    # Each image pass.
............_img
............_id
............_depth
............_normals
............_flow
........objects/    # Per-object data.
............positions
............forwards
............rotations
............velocities
............angular_velocities
........collisions/    # Collisions between two objects.
............object_ids
............relative_velocities
............contacts
........env_collisions/    # Collisions between one object and the environment.
............object_ids
............contacts
........camera_matrices/
............projection_matrix
............camera_matrix
....0001/
........ (etc.)

All object data is ordered to match object_ids. For example:
- static/mass[0] is the mass of static/object_ids[0]
- frames/0000/positions[0] is the position of static/object_ids[0]
The shape of each dataset in objects is determined by the number of coordinates. For example, frames/objects/positions/ has shape (num_objects, 3).
The shape of all datasets in collisions/ and env_collisions/are defined by the number of collisions on that frame.
- frames/collisions/relative_velocities has the shape (num_collisions, 3)
- frames/collisions/object_ids has the shape (num_collisions, 2) (tuple of IDs).
- frames/env_collisions/object_ids has the shape (num_collisions) (only 1 ID per collision).
- frames/collisions/contacts and frames/env_collision/contacts are tuples of (normal, point), i.e. the shape is (num_collisions, 2, 3).

`TransformsDataset`

from typing import List
from tdw_physics.transforms_dataset import TransformsDataset

class MyDataset(TransformsDataset):
    def get_scene_initialization_commands(self) -> List[dict]:
        # Your code here.

    def get_trial_initialization_commands(self) -> List[dict]:
        # Your code here.

    def get_per_frame_commands(self, resp: List[bytes], frame: int) -> List[dict]:
        # Your code here.

    def get_field_of_view(self) -> float:
        # Your code here.

A dataset creator that receives and writes per frame: Transforms, Images, CameraMatrices.

Ending a trial

A TransformsDataset trial has no "end" condition based on trial output data; you will need to define this yourself by adding the function def is_done():

    def is_done(self, resp: List[bytes], frame: int) -> bool:
        return frame > 1000 # End after 1000 frames.

Adding objects

`def get_add_object()`

Return: An add_object command.

from typing import List
from tdw_physics.transforms_dataset import TransformsDataset

class MyDataset(TransformsDataset):
    def get_trial_initialization_commands(self) -> List[dict]:
        commands = []
        # Your code here.
        commands.append(self.get_add_object(model_name="iron_box",
                                            library="models_core.json",
                                            object_id=self.get_unique_id(),
                                            position={"x": 0, "y": 0, "z": 0},
                                            rotation={"x": 0, "y": 0, "z": 0}))
        return commands

Parameter	Type	Default	Description
model_name	str		The name of the model.
position	Dict[str, float]	None	The position of the model. If None, defaults to `{"x": 0, "y": 0, "z": 0}`.
rotation	Dict[str, float]	None	The starting rotation of the model, in Euler angles. If None, defaults to `{"x": 0, "y": 0, "z": 0}`.
library	str	""	The path to the records file. If left empty, the default library will be selected. See `ModelLibrarian.get_library_filenames()` and `ModelLibrarian.get_default_library()`.
object_id	int		The ID of the new object.

.hdf5 file structure

static/    # Data that doesn't change per frame.
....object_ids
frames/    # Per-frame data.
....0000/    # The frame number.
........images/    # Each image pass.
............_img
............_id
............_depth
............_normals
............_flow
........objects/    # Per-object data.
............positions
............forwards
............rotations
........camera_matrices/
............projection_matrix
............camera_matrix
....0001/
........ (etc.)

All object data is ordered to match object_ids. For example:
- static/mass[0] is the mass of static/object_ids[0]
- frames/0000/positions[0] is the position of static/object_ids[0]
The shape of each dataset in objects is determined by the number of coordinates. For example, frames/objects/positions/ has shape (num_objects, 3).

`FlexDataset`

from typing import List
from tdw_physics.flex_dataset import FlexDataset

class MyDataset(FlexDataset):
    def get_scene_initialization_commands(self) -> List[dict]:
        # Your code here.

    def get_trial_initialization_commands(self) -> List[dict]:
        # Your code here.

    def get_per_frame_commands(self, resp: List[bytes], frame: int) -> List[dict]:
        # Your code here.

    def get_field_of_view(self) -> float:
        # Your code here.

A dataset creator that receives and writes per frame: Transforms, Images, CameraMatrices, and FlexParticles.

Adding objects

Controller.add_object() and Conroller.get_add_object() will throw an exception. You must instead use wrapper functions to add Flex objects. They will automatically cache the object ID, allowing the object to be destroyed at the end of the trial.

`def add_solid_object()`

Return: A list of commands to add a solid-body object.

from typing import List
from tdw_physics.flex_dataset import FlexDataset

class MyDataset(FlexDataset):
    def get_trial_initialization_commands(self) -> List[dict]:
        commands = []
        # Your code here.
        commands.extend(self.add_solid_object(model_name="microwave",
                                              library="models_full.json", 
                                              object_id=self.get_unique_id(),                                      
                                              position={"x": 0, "y": 0, "z": 0},
                                              rotation={"x": 0, "y": 0, "z": 0},
                                              scale_factor={"x": 1, "y": 1, "z": 1},
                                              mesh_expansion=0,
                                              particle_spacing=0.125,
                                              mass_scale=1))
        return commands

Parameter	Type	Default	Description
`model_name`	`str`		The model name.
`object_id`	`int`		The object ID.
`library`	`str`		The model librarian.
`position`	`Dict[str, float`]		The initial position of the object.
`rotation`	`Dict[str, float]`		The initial rotation of the object, in Euler angles.
`scale_factor`	`Dict[str, float]`	`None`	The object scale factor. If None, the scale is (1, 1, 1).
`mesh_expansion`	`float`	0
`particle_spacing`	`float`	0.125
`mass_scale`	float	1

`def add_soft_object()`

Return: A list of commands to add a soft-body object.

from typing import List
from tdw_physics.flex_dataset import FlexDataset

class MyDataset(FlexDataset):
    def get_trial_initialization_commands(self) -> List[dict]:
        commands = []
        # Your code here.
        commands.extend(self.add_soft_object(model_name="microwave",
                                             library="models_full.json",
                                             object_id=self.get_unique_id(),
                                             position={"x": 0, "y": 0, "z": 0},
                                             rotation={"x": 0, "y": 0, "z": 0},
                                             scale_factor={"x": 1, "y": 1, "z": 1},
                                             volume_sampling=2,
                                             surface_sampling=0,
                                             mass_scale=1,
                                             cluster_spacing=0.2,
                                             cluster_radius=0.2,
                                             cluster_stiffness=0.2,
                                             link_radius=0.1,
                                             link_stiffness=0.5,
                                             particle_spacing=0.02))
        return commands

Parameter	Type	Default	Description
`model_name`	`str`		The model name.
`object_id`	`int`		The object ID.
`library`	`str`		The model librarian.
`position`	`Dict[str, float`]		The initial position of the object.
`rotation`	`Dict[str, float]`		The initial rotation of the object, in Euler angles.
`scale_factor`	`Dict[str, float]`	`None`	The object scale factor. If None, the scale is (1, 1, 1).
`volume_sampling`	`float`	2
`surface_sampling`	`float`	0
`mass_scale`	`float`	1
`cluster_spacing`	`float`	0.2
`cluster_radius`	`float`	0.2
`cluster_stiffness`	`float`	0.2
`link_radius`	`float`	0.1
`link_stiffness`	`float`	0.5
`particle_spacing`	`float`	0.02

`def add_cloth_object()`

Return: A list of commands to add a cloth object.

from typing import List
from tdw_physics.flex_dataset import FlexDataset

class MyDataset(FlexDataset):
    def get_trial_initialization_commands(self) -> List[dict]:
        commands = []
        # Your code here.
        commands.extend(self.add_cloth_object(model_name="cloth_square",
                                              library="models_special.json",
                                              object_id=self.get_unique_id(),
                                              position={"x": 0, "y": 0, "z": 0},
                                              rotation={"x": 0, "y": 0, "z": 0},
                                              scale_factor={"x": 1, "y": 1, "z": 1},
                                              stretch_stiffness=0.1,
                                              bend_stiffness=0.1,
                                              tether_stiffness=0.1,
                                              tether_give=0,
                                              pressure=0,
                                              mass_scale=1))
        return commands

Parameter	Type	Default	Description
`model_name`	`str`		The model name.
`object_id`	`int`		The object ID.
`library`	`str`		The model librarian.
`position`	`Dict[str, float`]		The initial position of the object.
`rotation`	`Dict[str, float]`		The initial rotation of the object, in Euler angles.
`scale_factor`	`Dict[str, float]`	`None`	The object scale factor. If None, the scale is (1, 1, 1).
`mesh_tesselation`	`int`	1
`stretch_stiffness`	`int`	0.1
`bend_stiffness`	`int`	0.1
`tether_stiffness`	`float`	0
`tether_give`	`float`	0
`pressure`	`float`	0
`mass_scale`	`float`	1

`def add_fluid_object()`

Return: A list of commands to add a fluid object.

from typing import List
from tdw_physics.flex_dataset import FlexDataset


class MyDataset(FlexDataset):
    def get_trial_initialization_commands(self) -> List[dict]:
        commands = []

        # Your code here.

        # Cache the pool ID to destroy it correctly.
        pool_id = Controller.get_unique_id()
        self.non_flex_objects.append(pool_id)
        # Add the pool.
        commands.append(self.get_add_object(model_name="fluid_receptacle1x1",
                                            library="models_special.json",
                                            object_id=pool_id,
                                            position={"x": 0, "y": 0, "z": 0},
                                            rotation={"x": 0, "y": 0, "z": 0}))
        # Add a container here.

        # Add the fluid.
        commands.extend(self.add_fluid_object(position={"x": 0, "y": 1.0, "z": 0},
                                              rotation={"x": 0, "y": 0, "z": 0},
                                              object_id=Controller.get_unique_id(),
                                              fluid_type="water"))
        return commands

Parameter	Type	Default	Description
`object_id`	`int`		The object ID.
`position`	`Dict[str, float`]		The initial position of the object.
`rotation`	`Dict[str, float]`		The initial rotation of the object, in Euler angles.
`scale`	`Dict[str, float]`	`None`	The object scale factor. If None, the scale is (1, 1, 1).
`particle_spacing`	`float`	0.05
`mass_scale`	`float`	1
`fluid_type`	`str`		The name of the fluid type.

.hdf5 file structure

static/    # Data that doesn't change per frame.
....object_ids
....container/ # Flex container parameters.
........radius
........solid_rest
........fluid_rest
........planes
........(etc.)
....solid_actors/ # Flex solid object parameters.
........object_id
........mass_scale
........(etc.)
....soft_actors/ # Flex soft object parameters.
........object_id
........mass_scale
........(etc.)
....cloth_actors/ # Flex cloth object parameters.
........object_id
........mass_scale
........(etc.)
....fluid_actors/ # Flex fluid object parameters.
........object_id
........mass_scale
........(etc.)
frames/    # Per-frame data.
....0000/    # The frame number.
........images/    # Each image pass.
............_img
............_id
............_depth
............_normals
............_flow
........objects/    # Per-object data.
............positions
............forwards
............rotations
........camera_matrices/
............projection_matrix
............camera_matrix
........particles/    # Per-object particles.
........velocities/    # Per-object velocities.
....0001/
........ (etc.)

All object data is ordered to match object_ids. For example:
- static/mass[0] is the mass of static/object_ids[0]
- frames/0000/positions[0] is the position of static/object_ids[0]
The shape of each dataset in objects is determined by the number of coordinates. For example, frames/objects/positions/ has shape (num_objects, 3).
Regarding Flex data:
- All static Flex data is serialized to match the object_id array. e.g. static/solid_actors/mass_scale[0] is the mass_scale of static/solid_actors/object_id[0]. This data might not match the order of static/object_ids.
- Particles and velocities do match static/object_ids. frame/particles[0] is the particles for static/object_ids[0].
- frame/particles and frame/velocities are arrays of arrays of particle data and have shape (num_objects, len_particle_data).

`utils.py`

Some helpful utility functions and variables.

`def get_move_along_direction()`

Return: A position from pos by distance d along a directional vector defined by pos, target.

from tdw_physics.util import get_move_along_direction

p_0 = {"x": 1, "y": 0, "z": -2}
p_1 = {"x": 5, "y": 0, "z": 3.4}
p_0 = get_move_along_direction(pos=p_0, target=p_1, d=0.7, noise=0.01)

Parameter	Type	Default	Description
`pos`	`Dict[str, float]`		The object's position.
`target`	`Dict[str, float]`		The target position.
`d`	`float`		The distance to teleport.
`noise`	`float`	0	Add a little noise to the teleport.

`def get_object_look_at()`

Return: A list of commands to rotate an object to look at the target position.

from tdw_physics.util import get_object_look_at

o_id = 0 # Assume that the object has been already added to the scene.
p_1 = {"x": 5, "y": 0, "z": 3.4}
p_0 = get_object_look_at(o_id=o_id, pos=p_1, noise=5)

Parameter	Type	Default	Description
`o_id`	`int`		The object's ID.
`pos`	`Dict[str, float]`		The position to look at.
`noise`	`float`	0	Rotate the object randomly by this much after applying the look_at command.

`def get_args()`

Return: Command line arguments common to all controllers.

from tdw_physics.util import get_args
from tdw_physics.rigidbodies_dataset import RigidbodiesDataset

class MyDataset(RigidbodiesDataset):
    # Your code here.
    
if __name__ == "__main__":
    args = get_args("my_dataset")
    MyDataset().run(num=args.num, output_dir=args.dir, temp_path=args.temp, width=args.width, height=args.height)

Parameter	Type	Default	Description
`dataset_dir`	`str`		If you don't provide a `--dir` argument, the default output director is: `"D:/" + dataset_dir`

`extract_images.py`

python3 extract_images.py [ARGUMENTS]

Extract _img images from an .hdf5 file and save them to a destination directory.

Argument	Type	Default	Description
`--dest`	`str`		Root directory for the images.
`--src`	`str`		Root source directory of the .hdf5 files.

alters-mit / tdw_physics

tdw_physics

Requirements

Installation

Controllers

Changelog

Usage

How to Create a Dataset Controller

`RigidbodiesDataset`

Ending a trial

Adding objects

`def get_add_physics_object()`

`def get_objects_by_mass()`

`def get_falling_commands()`

`PHYSICS_INFO`

.hdf5 file structure

`TransformsDataset`

Ending a trial

Adding objects

`def get_add_object()`

.hdf5 file structure

`FlexDataset`

Adding objects

`def add_solid_object()`

`def add_soft_object()`

`def add_cloth_object()`

`def add_fluid_object()`

.hdf5 file structure

`utils.py`

`def get_move_along_direction()`

`def get_object_look_at()`

`def get_args()`

`extract_images.py`

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