Upcoming
Contact me for private & public talks and workshops: me@christoso.com

Pixar Animation Studios
Location: 🇺🇸 San Francisco, USA Jul 17 2019

Description: Presentation of work in Stylized Non Photreal Rendering, at Pixar Animation Studios.

Special thanks to Dylan Sisson.

Siggraph 2019
Location: 🇺🇸 Los Angeles, USA Jul 30 2019

Description: Presentation of work in Stylized Non Photreal Rendering, from Sony Pictures Imageworks latest feature film in Open Shading Language (OSL) for Arnold renderer.

Special thanks to Mike Ford, Steven Vargas and Larry Gritz at Sony Pictures Imageworks.

FMX 2019
Location: 🇩🇪 Stuttgart, Germany May 1 2019

Description: Presentation of work in Stylized Non Photreal Rendering. More info: https://fmx.de/program2019/event/15081

Special thanks to Christophe Hery, and the Filmakademie.

Filmakademie Workshop 2017
Location: 🇩🇪 Ludwigsburg, Germany Jul 3-5 2017

Description: Our 3rd workshop at the filmakademie in Ludwisgsburg, Germany. Covering HDRI capture studio-sessions and brand new material on Stylized Non Photoreal Rendering (NPR) in RenderMan.

Special thanks to Pixar's RenderMan Team, The Filmakademie.

Pixar's RenderMan User Group Vancouver
Location: 🇨🇦 Vancouver, Canada June 21 2017

Description: The very 1st Official Pixar RenderMan User Group Meeting in Vancouver! Held at the Waterfront Theatre on Granville Island, we had a great attendance. Speakers included: Max Liani from Pixar's RenderMan engineering group in Seattle, Christos Obretenov of LollipopShaders, Max Leonard from ILM Vancouver, and Mark Flanagan from Double Negative Vancouver.

Special thanks to Pixar's RenderMan Team, The Foundry, Max Liani, Matt Leonard, Mark Flanagan.

Foundry Katana User Group
Location: 🇨🇦 Vancouver, Canada April 19 2017

Description: "Join us for our first Katana meet-up in Vancouver. Katana is Foundry’s high efficiency CG look development and lighting tool, available for Windows and Linux. You’ll hear from Jordan Thistlewood, one of Foundry’s senior product managers, who is in town to talk about the latest developments in Katana, and the exciting things planned for 2017. Christos Obretenov of LollipopShaders will be joining us to showcase his latest work on "Layering with PxrLayerSurface and Katana." Refreshments and welcome start at 6:30 p.m, followed by our presentation at 7:00 p.m, leaving plenty of time for networking with our presenters and reps from Foundry before and after."

Special thanks to Jordan & Jen from The Foundry, Pixar's RenderMan Team.

Filmakademie Workshop 2015
Location: 🇩🇪 Ludwigsburg, Germany
Our 2nd workshop at the filmakademie in Ludwisgsburg, Germany. Covering HDRI capture studio-sessions and brand new material on the cutting-edge RIS technology in the latest RenderMan offering!
Day 1 AM: Image capture in vfx, Shading paradigms in vfx
Day 1 PM: Practical capture, Equipment use/setup, Lighting setup capture
Day 2 AM: Rendering with RIS in RenderMan: overview, RIS vs REYES.
Day 2 PM: Making Light maps, Making HDRIs (Photoshop+RV), Stitching maps (PtguiPro+RV), Gray/Color correction (Nuke+RV)
Day 3 AM: More EnvLight: Importance Sampling, Area Lights
Day 3 PM: Studio/Outdoor session, Practical capture II, More Lighting setup capture/ Hiresolution capture

Special thanks to Arkel Rasiah, Volker Helzle, the filmakademie.

Shanghai 2014 Private Workshop
"Intro to Path Tracing and RIS in RenderMan"
Location: 🇨🇳 Shanghai, China
5-day workshop teaching the instructors at SIVA in the latest Path Tracing and RIS technologies, who will then take this knowledge to craft their own courses for their students in the years to come.

Special thanks to Jun Zhang, SIVA.

Siggraph 2014 Talk
"Intro to Path Tracing and RIS in RenderMan"
Location: 🇨🇦 Vancouver, Canada
>> View the newsletter for full details including photos & renders!
>> View full talk description on the RenderMan site!.
Path Tracing and RIS in RenderMan Christos Obretenov – Shader Architect at LollipopShaders & Instructor at FXPHD Presentation – Covering some of the topics in his new course on FXPHD, Christos will be going over the brand new features in the latest RenderMan. These include the definition of RIS and how it differs from the traditional Reyes system, Uni-Directional Path Tracing vs Bi-Directional VCM through concepts and RenderManStudio sessions. Pros & Cons of Path vs VCM will be explored, as well as tips on settings to balance quality over noise. Also covered will be the new "Disney Principled BRDF" BxDF, including historial context of the paper it was based on, and its use as "PxrDisneyBRDF" in RenderManStudio.

Special thanks to Dylan Sisson & Pixar's RenderMan Team.

Siggraph 2013 Talk
"Path Tracing and New Physically Plausible Workflows"
Location: 🇺🇸 Anaheim, California
>> View the newsletter for full details including photos & renders!
>> View the full talk description on the RenderMan site!.
RenderMan Studio 18: Path Tracing and New Physically Plausible Workflows
Presentation – With 25 years of RenderMan evolution, RenderMan now offers a big toolbox of rendering techniques to choose from. Christos Obretenov will use RenderMan Studio 18 to take a look at RenderMan’s brand new path tracing rendering mode, comparing it to distributed ray tracing as well as the trusted Reyes approach. Christos will examine the pros & cons of each approach and when you might want to use one over the other on your project. Within the context of these rendering modes, we will explore some of the newer physically plausible shading/rendering techniques, such as IBL, geometric area lights, and the new subsurface scattering workflows.

Special thanks to Dylan Sisson & Pixar's RenderMan Team.

Filmakademie Workshop 2013
Location: 🇩🇪 Ludwigsburg, Germany
Arkell & Christos travelled to the Filmakademie to give a hands-on 3-day workshop on HDRI light capture & physically plausible shading.
Day 1 AM: Image capture in vfx, Shading paradigms in vfx
Day 1 PM: Practical capture, Equipment use/setup, Lighting setup capture
Day 2 AM: Making Light maps, Making HDRIs (Photoshop+RV), Stitching maps (PtguiPro+RV), Gray/Color correction (Nuke+RV)
Day 2 PM: Rendering with Light maps, Intro to RMS shaders: Envlight (dome), Sampling techniques, Energy Conservation & Normalized BRDF’s
Day 3 AM: More EnvLight: Importance Sampling, Area Lights
Day 3 PM: Studio/Outdoor session, Practical capture II, More Lighting setup capture/ Hiresolution capture
Day 4 AM: Other RMS shaders: GPSurface, Matte, RMSGlass (transparent objects, refraction), Environment Camera shader
Day 4 PM: Creative stitching/Tonemaping of HDRIs

Special thanks to Arkel Rasiah, Volker Helzle, the filmakademie.

Siggraph 2012 Talk on Physically Plausilbe Shading in RenderMan.
Location: 🇺🇸 Los Angeles, California
>> View The Newsletter for full details!
>> View the page on the RenderMan website for full list of speakers!
Exploration in Physically Plausible Shading Presentation – Christos will begin by examining a rendering scene with professionally captured unclipped HDRI maps and a traditional shaders & lights setup in PRMan, and see where it leads to artifacts and inconsistent material settings across different lighting environments. We then render the same scene but in our Physically Plausible Shading environment in PRMan16/17, demonstrate how our previous issues have been resolved, and introduce the physically plausible surface and light shaders. We talk about a full Physically Plausible system including energy conservation, physical properties in materials, lights with area for solid angle sampling, importance sampling, ray-tracing, as well as plausible fur and volumes.

Special thanks to Dylan Sisson & Pixar's RenderMan Team.

FMX Conference 2012
Location: 🇩🇪 Stuttgart, Germany
>> Read the newsletter for full info!
The Importance of Unclipped HDRI Lightmaps and Resulting Material Setup in Production
In CG film production, we rely on captured HDRI maps to drive realistic lighting response from the environment. Many of these HDRI Environment Maps, or Lightmaps, used in production by either on-set capture or purchased through a 3rd party, contain clipped high values, especially the sun. When using clipped maps from a look development process through to lighting on a production, inconsistency in material settings result, creating unrealistic and inconsistent responses in materials. One major source for clipping these maps for use in production and the reason they have been so prevalent has been due to non importance-sampled shader setup requiring too many samples to practically deal with unclipped map sources. With Renderman’s introduction of Physically Plausible Shading, and other proprietary importance-sampled shading setups becoming more common, it has become more practical and necessary to use properly captured and unclipped HDRI’s. In our presentation we test multiple unclipped HDRI Lightmaps using fully raytraced importance-sampled shading, and compare with clipped HDRI maps found in production.

Special thanks to Christophe Hery, Arkel Rasiah, the filmakademie.

Life of Pi feature film

Part of the team at MPC studio in Vancouver Canada to receive Academy Oscar for Best Visual Effects. Visual Effects Supervisor: Guillame Rocheron.