COLOR HELPS TO SELL VEHICLES

Transcription

1 COLOR HELPS TO SELL VEHICLES Like/Dislike decisions made in seconds 40% of buyers will choose a different vehicle if their color choice is not available. Emotional connection with owner 1

2 VEHICLE DESIGN IS COMPLETELY DIGITAL Except for Color Design DIGITAL COLOR REPRESENTATIONS ARE NOT LINKED TO REAL COLORS 2

3 DIGITAL COLOR REPRESENTATIONS ARE NOT LINKED TO REAL COLORS Colors used to be simple. but not anymore! 3

4 GONIO-APPARENT COLORS Metallic, Mica, Glass, Synthetic Flakes Color changes depending on the angle of illumination and observation. L*: 0 (black) 100 (diffuse white), a*: <0 (green) - >0 (red), b*: <0 (blue) - >0 (yellow) X-Rite and Byk-MAC Spectrophotometers geometry LONG-TERM VISION Digital Color Design Designer/Artist Friendly Interface Inspiration Digital Color Paint Can Color Mastering Replace physical samples with digital data and representation Color Harmony 4

5 AUTOMOTIVE PAINT SYSTEM Pigment in Clearcoat Flakes Transparent Pigments Clearcoat 50 um Gloss, protects basecoat from UV light Basecoat 20 um Primer 25 um Electrocoat 25um Phosphate 1um Substrate (EG Steel, Aluminum, SMC ) Color, metallic flakes Smoothes E-coat, protects E- coat from light, promotes adhesion Provides corrosion protection Provides corrosion protection PHYSICS-BASED MODEL OF AUTOMOTIVE PAINT COLOR Metallic Flake Size Shape Amount Orientation Distribution We Need This Data to Generate Model Process Bell speed, shaping air, tip speed, voltage Film Build Rheology control additives Improved Alignment 5

6 SILVER TEST PANELS LASER SCANNING CONFOCAL MICROSCOPY (LSCM) Top down view of complete paint system Adjust focal plane to capture light at various depths into coating system Recombine images to get full 3-D view of system Image: Mater. Char., 60, 603,

7 FLAKE MORPHOLOGY OF SILVER AUTOMOTIVE CLEARCOAT/BASECOAT SYSTEM ~17x12mm illumination area LSCM 30 um ~100x100mm LSCM measurement area Metallographic Cross Section LSCM Visual Data Height Field Data Spatial resolution: 0.1 (x-dir.) x 0.1 (y-dir.) x 0.25mm (z-dir.) Typical image stack: x x 25mm 7

8 ANGULAR ORIENTATION Flake 1 Flake 2 Azimuth Surface Normal DISTRIBUTION FUNCTION OF SURFACE NORMALS Gamma Distribution, not Normal Distribution Two parameters: Shape and Scale PDF = 1 θ k x k 1 e x θ Γ(k) 8

9 FLAKE ORIENTATION DISTRIBUTION PDFS FLAKE GEOMETRY VS. SPECTROPHOTOMETER GEOMETRY Ill/Obs Angle Degrees from Normal n=1 n 1.5 q OUT q IN 45/ / / / / / / / / / / q 3 q 2 q 2 θ 2 = sin sin θ IN θ 3 = sin sin θ OUT q F θ F = θ 2 θ

10 MEASURING RESULTING SCATTERING Illum/Obs Sample 1 Sample 2 Sample 3 45/ / / / / / / / / / / SCATTERING PROFILE FLAKE ORIENTATION L* a Flake Orientation 10

11 FLAKE ORIENTATION DISTRIBUTION PDFS RAY TRACING INVESTIGATION Examine scattering profile for simulated flake containing systems Assess differences in scattering profiles due to orientation estimation techniques LSCM BRDF MASP Convert back to multi-angle spectrophotometer measurements. 11

12 RAY TRACING GEOMETRY Shoot 4M+ rays into sample Collimated, controlled divergence Concentric circular or random source Collect exiting rays Project hemisphere Polar coordinates Define surface: Flakes in transparent binder w/ CC over Flake size, shape, v/o, orientation distribution, thickness SILVER PAINT SYSTEM SIMULATION 70mm BC/CC Physical System Information 0.18 P:B Average flake size ~15x15mm Two flake thicknesses (0.3 and 1.33mm) Approx. density of binder and flakes is 1.2 and 2.7 g/cm 3 respectively 20mm 15mm Preliminary Simulation Assumptions Range of flake sizes (based on measured size distributions) Two flake thicknesses Azimuthal angle random Rectangular shape flakes 85% reflection from flake 6mm radius perfectly collimated source consisting of 4.6M rays One wavelength of light (546 nm) Piercing of flakes allowed 12

13 MULTI-ANGLE SPECTROPHOTOMETER /BRDF MEASUREMENTS SILVER #2 SIMULATION RESULTS Silver #2 LSCM gamma dist full simulation with 10/75% diffuse/specular reflection from flake Silver #2 BRDF gamma dist full simulation with 10/75% diffuse/specular reflection from flake Silver #2 MASP gamma dist full simulation with 10/75% diffuse/specular reflection from flake L = 116( Y Y n ) 1/

14 SIMULATED VS. MEASURED L* VALUES (SILVER #2) DIRECT FIT TO DATA (2 ND ORDER EXPONENTIAL FIT) Silver #2 LSCM Silver #2 BRDF Silver #2 MASP 14

15 SIMULATED VS. MEASURED L* VALUES (SILVER #2) OPTIMIZED DISTRIBUTION Silver #2 optimized gamma dist (a=2.2, b=3.2) 15

16 ONGOING RESEARCH Identify if/when BRDF approximation breaks down Flake loading Disorientation Flake Thickness Examine flake roughness vs. edge effects and multiple scattering Develop way of creating large scale flake simulation without piercing of flakes LSCM on different flake size, and v/o to assess distribution function generality Quantify effect of wave optics upon scattering profile SUMMARY Attempting to bring color design into the digital age Complex, gonio-apparent colors are challenging Flake alignment is the critical variable that need to be understood. LSCM is a powerful tool to measure flake alignment distribution. Ray tracing simulations allow us to investigate experimentally challenging variables. Much more work needs to be completed before we can provide mathematical models for computer shaders. 16

17 SUMMARY ACKNOWLEDGEMENTS BASF, DuPont, PPG, RTT Gary Meyer University of Minnesota TracePro Center for Advanced Microscopy at Michigan State University 17