THREE-DIMENSIONAL MODEL MANIPULATION AND RENDERING

1 . A method, performed by a computing device, for editing a three-dimensional (3D) model, the method comprising:

representing the 3D model using a first volume-based representation;

determining a first mesh-based representation of the 3D model from the volume-based representation;

providing a first view of the first mesh-based representation of the 3D model for display on a user interface;

receiving an edit for the 3D model from a user interacting with the user interface;

modifying the first volume-based representation based on the edit to create a second volume-based representation of the 3D model;

determining a second mesh-based representation of the 3D model based on the second volume-based representation; and

providing a second view of the second mesh-based representation of the 3D model for display on the user interface.

2 . The method as set forth in claim 1 , wherein representing the 3D model using the first volume-based representation comprises representing the 3D model using volume density values of locations within a 3D workspace, wherein the 3D model is represented by a set of the locations having volume density values above a threshold.

3 . The method as set forth in claim 2 , wherein modifying the first volume-based representation comprises modifying the volume density values of locations within the 3D workspace based on the edit.

4 . The method as set forth in claim 1 , wherein representing the 3D model using the first mesh-based representation comprises representing a surface of the 3D model using a plurality of interconnected polygon surfaces.

5 . The method as set forth in claim 1 , wherein representing the 3D model using the first mesh-based representation comprises identifying a mesh surrounding the set of locations within the 3D workspace having volume density values above the threshold in the first volume-based representation.

6 . The method as set forth in claim 1 , wherein modifying the first volume-based representation comprises:

identifying a set of locations in a 3D workspace based on a position of the edit relative to the view of the 3D model displayed on the user interface;

determining a type of the edit; and

determining the second volume-based representation by increasing or decreasing volume density values of the second set of locations in the first volume-based representation based on the type of the edit.

7 . The method as set forth in claim 1 , wherein determining the second mesh-based representation comprises determining the second mesh-based representation based on the second volume-based representation using a triangulate process.

8 . The method as set forth in claim 1 , wherein the step for editing the 3D model comprises modifying a plurality of parallel, planar, cross-sections of a 3D workspace, wherein the cross-sections comprise 2 dimensional (2D) grey scale representations of volume density values of the 3D model.

9 . The method as set forth in claim 1 , wherein receiving the edit for the 3D model comprises receiving an input identifying a location on the user interface that is not on a vertices or surface of the first mesh-based representation of the 3D model.

10 . The method as set forth in claim 1 ,

wherein receiving the edit for the 3D model comprises receiving a first input identifying a location on the user interface and receiving a second input identifying a filter to be applied to the 3D model; and

wherein modifying the first volume-based representation comprises modifying the first volume-based representation by applying the filter to volume density values based on the location.

11 . The method as set forth in claim 10 , wherein receiving the first input identifying the location comprises receiving a selection of a selection mask identifying the location.

12 . The method as set forth in claim 1 ,

wherein receiving the edit for the 3D model comprises receiving input to add a layer the 3D model, wherein the first volume-based representation represents the 3D model by specifying density values for the 3D model using a set of one or more layers, each of the one or more layers separately representing density values for locations in a separate 3D workspace; and

wherein modifying the first volume-based representation comprises:

creating a new layer to represent density values in a new 3D workspace;

adding the new layer to the set of layers; and

combining density values from layers of the set of layers to represent the 3D model.

13 . The method as set forth in claim 1 ,

wherein receiving the edit for the 3D model comprises receiving input to edit the 3D model based on a position of a brush on the user interface; and

wherein modifying the first volume-based representation comprises:

identifying a location in a 3D workspace corresponding to the position of the brush;

sensing pressure applied by an input device at the position; and

modifying volume density values at the location based on the sensed pressure.

14 . The method as forth in claim 1 ,

wherein receiving the edit for the 3D model comprises receiving input to edit the 3D model based on a stroke of a brush through multiple positions on the user interface; and

wherein modifying the first volume-based representation comprises:

identifying locations in a 3D workspace corresponding to the positions of the brush during the stroke; and

modifying volume density values at the locations.

15 . The method as set forth in claim 1 , wherein receiving the edit for the 3D model comprises receiving the edit from a touch-based interface or via a virtual reality (VR) interface.

16 . A computer-based system for editing a three-dimensional (3D) model, the system comprising:

a means for representing the 3D model using a volume-based representation;

a means for representing the 3D model using a mesh-based representation;

a means for providing a view of the 3D model for display on a user interface based on the mesh-based representation; and

a means for editing the 3D model by modifying the volume-based representation based on an edit received from a user interacting with the user interface.

17 . The computer-based system as set forth in claim 16 , wherein the means for editing the 3D model comprises a means for increasing or decreasing volume density values of a set of locations in the volume-based representation.

18 . A non-transitory computer-readable medium comprising instructions for causing a computing device to perform operations comprising:

representing the 3D model using a volume-based representation and a mesh-based representation;

displaying the 3D model on a user interface based on the mesh-based representation; and

editing the 3D model based on edits received from a user interacting with the user interface by modifying the volume-based representation of the 3D model.

19 . The non-transitory computer-readable medium of claim 18 , wherein representing the 3D model using the volume-based representation and the mesh-based representation comprises determining the mesh-based representation by identifying a mesh surrounding locations within the 3D workspace having volume density values above a threshold in the volume-based representation.

20 . The non-transitory computer-readable medium of claim 18 , wherein editing the 3D model comprises:

identifying a set of locations in a 3D workspace based on a position of the edit relative to the view of the 3D model displayed on the user interface;

determining a type of the edit;

determining a modified volume-based representation by increasing or decreasing volume density values of the second set of locations based on the type of the edit; and

determining a modified mesh-based representation based on the modified volume-based representation.