Download presentation

Presentation is loading. Please wait.

1
**Computer-Generated Watercolor**

Cassidy J. Curtis Sean E. Anderson Joshua E. Seims Kurt W. Fleischer David H. Salesin

2
**Outline Introduction Related work Background Overview**

Watercolor simulation Rendering Applications Results Conclusion

3
Introduction Various artistic effects of watercolor

4
**Related work Simulating artists’ traditional media and tools**

Watercolor : [David Small 1991] Sumie : [Guo and Kunii 1991] Commercial package Fractal Design Painter

5
**Background Properties of watercolor Watercolor paper Pigment Binder**

Surfactant

6
**Background Watercolor Effects a) dry-brush b) Edge darkening**

c) Backruns d) granulation and separation of pigments e) Flow patterns f) color glazing

7
**Overview Computer-generated watercolor**

1. Fluid (and pigment) simulation for each glaze 2. Rendering Glaze: physical properties, area

8
Fluid simulation Three-layer model

9
**Fluid simulation Paper Generation**

Height field model ( 0 < h < 1 ) Based on pseudo-random process Fluid capacity c: proportional to h

10
**Fluid simulation Main loop Moving Water Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments For each time step

11
**Fluid simulation Main loop Moving Water Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments For each time step

12
**Moving water conditions of water 1. To remain within the wet-area mask**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments conditions of water 1. To remain within the wet-area mask 2. To flow outward into nearby region 3. To be damped to minimize oscillating waves 4. To be perturbed by the texture of the paper 5. To be affected by local changes 6. To present the edge-darkening effect Navier-Stoke Eq. Viscous drag k Paper slope h Mass conserv. Flow outward

13
**Fluid simulation Configuration Staggered grid i,j Moving Water**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Configuration Staggered grid i,j

14
**Fluid simulation Updating the water velocities**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Updating the water velocities Governing Equation (2D Navier-Stoke Eqn.)

15
**Fluid simulation Derivation of Navier-Stoke Eqn.(1/5) Basic Eqn.:**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Derivation of Navier-Stoke Eqn.(1/5) Basic Eqn.: For unit volume:

16
**Fluid simulation Derivation of Navier-Stoke Eqn.(2/5)**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Derivation of Navier-Stoke Eqn.(2/5) Two kind of measurements fluid solid Control volume

17
**Fluid simulation Derivation of Navier-Stoke Eqn.(3/5) Eulerian view**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Derivation of Navier-Stoke Eqn.(3/5) Eulerian view

18
**Fluid simulation Derivation of Navier-Stoke Eqn.(4/5) Governing Eq.:**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Derivation of Navier-Stoke Eqn.(4/5) Governing Eq.: Forces: Gravity: Viscosity: Pressure:

19
**Fluid simulation Derivation of Navier-Stoke Eqn.(5/5)**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Derivation of Navier-Stoke Eqn.(5/5) Navier-Stoke Eqn. For 2D case,

20
**Fluid simulation Updating the water velocities**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Updating the water velocities Numerical integration for u

21
**Fluid simulation Updating the water velocities**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Updating the water velocities Applying paper slope effect: Applying Drag Force:

22
**Fluid simulation Mass conservation (1/3) Divergence free condition**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Mass conservation (1/3) Divergence free condition

23
**Fluid simulation Mass conservation (2/3)**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Mass conservation (2/3) Relaxation (iterative procedure)

24
**Fluid simulation Mass conservation (3/3)**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Mass conservation (3/3) Relaxation (iterative procedure)

25
**Fluid simulation Edge darkening To flow outward**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Edge darkening To flow outward Remove some water at the boundary

26
**Fluid simulation Edge darkening dry wet 1 M .1 .4 .6 1 .9 M’ .4 .1**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Edge darkening dry wet 1 M .1 .4 .6 1 .9 M’ .4 .1 (1-M’)M

27
**Fluid simulation Main loop Moving Water Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments For each time step

28
**Fluid simulation Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Moving Pigments To move as specified by the velocity field u,v

29
**Fluid simulation Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Moving Pigments To move as specified by the velocity field u,v

30
**Fluid simulation Main loop Moving Water Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments For each time step

31
**Fluid simulation Transferring Pigments Adsorption and desorption**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Transferring Pigments Adsorption and desorption Adsorption Desorption

32
**Fluid simulation Main loop Moving Water Moving Pigments**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments For each time step

33
**Fluid simulation Backruns Diffusing water through the capillary layer**

Applying Capillary Flow Moving Water Moving Pigments Transferring Pigments Backruns Diffusing water through the capillary layer Spreading slowly into a drying region Transfer water to its dryer neighbors until they are saturated

34
**Fluid simulation Drybrush effect**

By excluding any lower pixel than threshold

35
**Rendering Optical properties of pigments**

Optical composition – subtractive color mixing

36
**Rendering S K Optical properties of pigments Kubelka-Munk (KM) Model**

To compute Reflectance R and Transmittance T using K and S backscattered S unit length absorbed K

37
Rendering Optical properties of pigments Kubelka-Munk (KM) Model

38
**Rendering Optical properties of pigments Kubelka-Munk (KM) Model**

For multiple layers

39
**Rendering Optical properties of pigments We need S and K values**

Kubelka-Munk (KM) Model We need S and K values Make user choose them intuitively

40
Rendering Optical properties of pigments User selects Rw and Rb

41
Rendering Optical properties of pigments User selects Rw and Rb

42
**Applications 1. Interactive painting with watercolors**

2. Automatic image “watercolorization” 3. Non-photorealistic rendering of 3D models

43
Applications 1. Interactive painting with watercolors

44
**Applications 2. Automatic image “watercolorization” Color separation**

Brushstroke Planning

45
**Applications 2. Automatic image “watercolorization” Color separation**

Determine the thickness of each pigment by brute-force search for all color combinations

46
**Applications 2. Automatic image “watercolorization”**

Brushstroke planning

47
**Applications 3. Non-photorealistic rendering of 3D models**

Using “photorealistic” scene of 3D model

48
Results

49
Results

50
Results

51
Results

52
**Conclusion Various artistic effects of watercolor Application**

Water and pigment simulation Pigment Rendering Application Interactive system Automatic “watercolorization” of 2D and 3D

53
**Further work Other effects Automatic rendering Generalization**

Spattering and drybrush Automatic rendering Applying automatic recognition Generalization Integration of Wet-in-wet and backruns Animation issues Reducing temporal artifacts

Similar presentations

OK

CSE 872 Dr. Charles B. Owen Advanced Computer Graphics1 Water Computational Fluid Dynamics Volumes Lagrangian vs. Eulerian modelling Navier-Stokes equations.

CSE 872 Dr. Charles B. Owen Advanced Computer Graphics1 Water Computational Fluid Dynamics Volumes Lagrangian vs. Eulerian modelling Navier-Stokes equations.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on elements of a story Ppt on role of foreign institutional investment in india Ppt on marketing management Ppt on open access Ppt on index numbers meaning A ppt on loch ness monster found Ppt on pricing policy to maximize Ppt on movie 300 Ppt on cross-sectional study psychology Ppt on guru granth sahib