Rendering PDF

Rendering 3D Modelling Games and Multimedia Authors: Alexandrino Gonçalves and Nuno Rodrigues Last revision: 25/11/2024  Rendering Rendering is the process of generating an image from a 2D or 3D model (that may contain geometry, vi...

Rendering 3D Modelling Games and Multimedia Authors: Alexandrino Gonçalves and Nuno Rodrigues Last revision: 25/11/2024  Rendering Rendering is the process of generating an image from a 2D or 3D model (that may contain geometry, viewpoints, textures, lighting and shading information) by means of computer software. In the graphics pipeline, it is the last major step, giving the final visual appearance to the models and animations developed 3DM 2  Rendering Process Rendering pipeline: Models Camera position Light sources Surface characteristics Illumination/shading technique Rendering Save file(s) 3DM 3 Rendering 3DM 4 Rendering 3DM 5  Rendering Software Despite the 3D model; the accurate placement of the light sources; the surface features perfectly defined; the texture methods used; etc., the overall quality of the rendered scene is widely dependent on the type of rendering engine used Since 3D rendering is the final stage of industries such as digital games, special effects, animation movies, or architectural visualization, there are several different render engines available 3DM 6  Rendering Software POVray 3DM 7  Rendering Software Maxwell ($199/month - plugin) 3DM 8  Rendering Software Corona (65€/month - plugin) 3DM 9  Rendering Software Octane ($25/month - plugin) 3DM 10  Rendering Software Cycles (Free/Blender - plugin) 3DM 11  Rendering Software V-Ray (110€/month - plugin) 3DM 12  Rendering Software Redshift ($47/month) 3DM 13  Rendering Software Mental Ray (discontinued) 3DM 14  Rendering Software Arnold ($50/month - $400/year - $1200/3 year - Plugin) 3DM 15  Rendering Software Renderman (Pixar) ($595 – plugin) 3DM 16  Rendering Software Unreal Engine 3DM 17 Hidden Surface Removal / Occlusion Before objects in a scene can be rendered, an occlusion procedure need to be conducted A hidden surface removal process (also known as occlusion) is implemented to determine which polygons must be rendered (the polygons that are not visible don’t need to be rendered) 3DM 18  Z-Buffer Occlusion There are many methods for hidden surface removal, but one of the most used is Z-Buffer (also known as depth-buffer) developed by Edwin Catmull in 1973 Z-Buffer is one of the simpler and easier to implement hidden surface removal rendering methods, either by software or hardware Z-Buffer gets its name from the fact that the objects in the scene are sorted and stored by their z coordinate 3DM 19  Z-Buffer Occlusion It uses two main buffers (data structures): Refresh buffer: to store the colour for each pixel Z-buffer: to store the z (depth) value for each pixel 3DM 20  Z-Buffer Occlusion Z-Buffer considerations: It may be used in any object, since the colour and z value may be calculated in any point – This is clearly one of its main advantages since it does not need for a 3D intersection algorithm Very easy to implement Needs a lot of memory 3DM 21  Back-Face Culling Back-face culling determines whether a polygon of a graphical object is potentially visible For optimization purposes it can draw only one face of each polygon (the one facing the camera) Perfectly suited for closed and opaque geometry 3DM 22 Back-Face Culling 3DM 23  Rendering in Layers A good method to achieve a sustainable and predictable optimal result is to render the scene in multiple separate layers (also known as rendering passes) This provides flexibility in determining the final look of the scene Keeping independent each set of surface characteristics facilitates changing just one or two layers while keeping the others intact 3DM 24  Rendering in Layers Like suggested in texture mapping, rendering in layers can also include: Z-Depth Shadows Diffuse Specular Occlusion Colour Displacement Transparency Etc. 3DM 25  Network Rendering Due to the technological advances, the time needed for the rendering process is continuously decreasing The rendering time can be speed up by using a computer network to generate all the renders for your job There are two main strategies to implement network rendering: Distributed rendering Remote rendering 3DM 26  Distributed Rendering Distributed rendering consists of sending portions of a rendering job to different machines in the network For example, the top half of a scene is rendered in one machine and the bottom half on another This methodology requires that the rendering software can split a rendering job into several sections and then put the results back together 3DM 27  Remote Rendering When the rendering is done in a different machine where the model of the job render is stand When a job render requires several different renders (for video animation production, for example), normally this method uses a client/server paradigm The server (normally the user workstation) manages the job render by addressing each needed frame to a specific machine and in the final assembles all frames of that job 3DM 28  Render Farm Nowadays, network rendering is implemented with the use of Render Farms Render farms are locations with a considerable number of computers dedicated solely to remote rendering These render farms may be in the same building of its owner, in a different building, or even in a different city or country Several companies (particularly big studios) have their own render farms, but they can also be rented Sdfms sçfmçslfksç sçldfjjsl 3DM Sdfms sçfmçslfksç sçldfjjsl 29 Render Farms for Rent Source: http://rentrender.com 3DM 30  Hardware Capabilities Until some years ago, these complex rendering calculations may took several, hours, days or months to conclude For example, the rendering of each frame of the first big success of Renderman (Toy Story - 1995) took 7 hours to conclude With today’s hardware capabilities, this heavily demanding procedure can be done in real-time 3DM 31  Hardware Capabilities This is possible because many advanced rendering algorithms are natively built into the hardware chip, such as: Z-Buffer Antialiasing Shadow volume acceleration Multiple parallel rendering pipelines Multiple textures management Fast tessellation for dynamic LODs 3DM 32  Hardware Capabilities Rendering capabilities of GPU gaming platforms: PlayStation 5: 10.3 TFlops (10.3 x 1012 floating-point operations per second) PlayStation 5 Pro: 16.7 TFlops Xbox Series X: 12 TFlops Nintendo Switch: 1 Tflops Nintendo Switch 2: ≈2 TFlops handheld and ≈3.5 docked Rendering capabilities of a high-end graphics card: Nvidia RTX 4090: 82.58 TFlops (Real-Time Ray-Tracing in Games) 3DM 33 Real-Time Rendering 3DM 34  Real-Time Rendering Nanites (UE5) Nanite is the Unreal Engine 5 new virtualized geometry system, which uses a new internal mesh format (Nanite Meshes) A Nanite mesh continues to be a triangle mesh with a lot of level of detail and compression applied to its data It uses an automatic Level of Detail (LOD) approach Instead of using steps for the Mesh-Detail LODs, nanite is a more tessellation-oriented approach, where the transitions from low poly to high poly meshes are perfectly smooth, without any noticeable detail-stepping 3DM 35  Realistic vs Stylized Does everything need to be photorealistic? 3DM 36  Non-Photorealistic Rendering Non-photorealistic rendering is an alternative to conventional, photorealistic rendering Aesthetic images that look as if they were created with traditional techniques Aims to make visual communication more effective Widely used in the gaming industry 3DM 37  Non-Photorealistic Rendering Areas of application: Architectural illustration Storytelling Metaverse Entertainment ▪ Comics ▪ Animation ▪ Videogames 3DM 38  Non-Photorealistic Rendering Mimic artistic styles: Pen/ink drawing Watercolour Impressionism Simulating different mediums: Types of paper Through water 3DM 39 Non-Photorealistic Rendering 3DM 40 Non-Photorealistic Rendering 3DM 41  Non-Photorealistic Rendering Used in still images (2D) But also in 3D computer animation and videogames It is also known as toon shading 3DM 42  Toon Shading Toon shading is a cartoon style: Dominated by large areas of flat colour With stylised highlights and shadows Shading Toon Shading 3DM 43 Non-Photorealistic Rendering Videogames Street Fighter IV (2009) 3DM 44 Non-Photorealistic Rendering Videogames Bioshock Infinite (2013) 3DM 45 Non-Photorealistic Rendering Videogames Bioshock Infinite (2013) 3DM 46 Non-Photorealistic Rendering Videogames Bordelands 3 (2019) 3DM 47 Non-Photorealistic Rendering Videogames The Legend of Zelda: Tears of the Kingdom (2023) 3DM 48 Non-Photorealistic Rendering Techniques Done through simulations of how traditional materials, like paint pigments, are distributed on a surface With modified versions of existing shading techniques 2D image processing techniques: Post processing filters Can be applied to 3D models after being rendering with realistic techniques 3D rendering techniques: Toon shaders 3DM 49 Non-Photorealistic Rendering Software Liquid+ (3DS Max) Maneki Toon (Maya) MNPRX (Maya) Pencil+ (Maya/3DS Max) Arnold (with Toon Shaders) Renderman (with Toon Shaders) Blender NPR 3DM 50  Rendering Considerations Use powerful image file formats to store your renders Always keep the highest quality and resolution rendered images Save your work often Consider the limitations of your computer Meet the deadlines Check the rendering options of your software 3DM 51  Rendering Considerations Exploit the strengths of your software: Very often, the best rendering results are achieved with just a few well-chosen shading parameters. Too many shading parameters not only extend the time needed to render the scene but might not contribute to the quality of the final result 3DM 52  Rendering Considerations Make several rendering tests Preview your work as you developed it: Simple shading techniques Render only some objects Turn off some light sources Render only some areas of the scene 3DM 53  Rendering Considerations Since the rendering process can be very demanding, it is common to generate rendering previews with smaller resolutions and lower quality in order to detect flaws or problems to be solved In the same manner when the geometry and shading in each scene are too complex, it is common to render different components separately 3DM 54  Rendering Considerations Some render problems can be related to modelling: Concave or open polygons Bad UV mapping Intersecting Small holes between surfaces that are supposed to be connected Problems (lost of information) due to exportation between different software applications Objects that contain other objects which are not supposed to be there 3DM 55  Rendering Considerations Optimize your renderings: Use only the amount of light necessary When possible, use texture-mapping techniques instead of ray tracing techniques When ray tracing is a must, try to keep the ray tracing depth value down Or use selective ray tracing where only objects near the camera are ray traced, while the ones far away are rendered with faster illumination techniques 3DM 56  Rendering Considerations Optimize your renderings: Try to keep the number of polygons down Use compositing techniques to assemble separate renderings into one Render critical portions of the scene before rendering the entire scene Preview the ultimate images in the final medium dfdsssfsdfss 3DM 57