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Table of Contents

Rendering with JPatch

To render a still or animated scene, use JPatch’s Animator module (select Start JPatch Animator from the JPatch Launcher dialog window). To select POV-Ray, select Options | Renderer Options… from the menu. In the Renderer Settings dialog, go to the Preferred Renderer dropdown and choose POV-Ray.

At the top of the Renderer Settings dialog are a number of settings common to all renderers that JPatch can use, including:

  • Resolution (default is 300×300)
  • Aspect ratio (default is 1:1)
  • Background Color
  • Preferred Renderer
  • Working Directory
  • Delete per-frame files after rendering

Rendering a Single Frame

To render a single frame, create a scene in the Animator, and then choose File | Render Current Frame to render the current frame. JPatch will use the Preferred Renderer selected in the Renderer Settings dialog. The image will be stored in the Working Directory (also set in the Renderer Settings dialog).

Rendering a Series of Frames

JPatch is currently unable to create a video file; animations will be rendered as a series of frames stored in the Working Directory. These can be assembled into an video file using an external tool.

To render a series of frame, create a scene in the Animator, and then choose File | Render Animation. In the Render Animation dialog, enter the First Frame and Last Frame, and press OK. JPatch will render the frames using the Preferred Renderer (selected in the Renderer Settings dialog), and store the images in the Working Directory (also set in the Renderer Settings dialog).

Inyo

Inyo is a free renderer written in Java for use with JPatch.

Download & Installation

Inyo is compiled into JPatch, and so does not have require separate installation.

Using Inyo as the Preferred Renderer

In the Renderer Settings dialog, choose Inyo as the Preferred Renderer. Choosing the Inyo tab in the Preferred Renderer will allow you to set various parameters, including:

  • Texture Path. This is the location where Inyo will search for any textures. Not currently implemented.
  • Mesh Density. JPatch converts patches into triangular mesh before sending it to Inyo to be rendered. Higher densities will result in smoother models, but will take longer to render.
  • Supersampling Level. Supersampling breaks a pixel up into subpixels, and uses the averaged result as the pixel’s final color. Supersampling creates smoother images, but increases rendering time. If an image has “jagged” edges, increase the supersampling level of the image. Supersampling at 1 mean no supersampling, supersampling at 2 means 4 samples (2×2) per pixel, at 3 requires 9 samples (3×3) per pixel, and at 4 requires 16 (4×4) samples per pixel.
  • Supersampling Method. Inyo can either supersample all pixels (Everything), or only at areas of high contrast (Adaptive). Adaptive is much faster. Ignored if Supersampling Level is set to 1.
  • Soft-Shadow Samples. The size parameter of a lightsource indicates the radius of the lightsource. Point light sources have a radius of 0, and generate “hard” shadows, with well-defined edges. Increasing the radius of the lightsource will spread the light out, and blur the shadow edges, creating “soft” shadows. These lightsources are sampled randomly. The more Soft-Shadow Samples, the smoother the blur of the shadow edge will appear, but at the cost of increased rendering time. Using a Soft-Shadows Samples value of 0 will cause all lights to be treated as point lights (with hard shadows), even if the have a non-zero radius.
  • Transparent Shadows. If this option is selected, transparent objects will cast transparent shadows. Otherwise, they will cast solid shadows. Using this option will increase rendering time.
  • Caustics. Caustics are a light effect caused by light focusing as it passes through a transparent object. Inyo doesn’t support true caustics. However, selecting this option will cause Inyo to generate “fake” caustics, which are much faster to calculate. This option is ignored if Transparent Shadows is off.
  • Oversample Caustics. If this option is checked, Inyo will spend more time trying to create more realistic “fake” caustice. This option is ignored if Transparent Shadows or Caustics is turned off.
  • Ambient Occlusion. This option causes Inyo to simulate global illumination - the effect of light bouncing from all directions - using a method called ambient occlusion, which estimates how much ambient light is blocked (occluded) by sending out sample rays to see how many objects are nearby.
  • Ambient Occlusion Max Distance. This is the maximum distance an object can be away from another object for the ambient occlusion algorithm to consider it as blocking the light. This option is ignored if Ambient Occlusion is not set.
  • Ambient Occlusion Samples. Ambient occlusion uses random sampling. Like Soft-Shadow Samples, having a larger sample size will result in a less grainy result, but at the cost of a longer render time. This option is ignored if Ambient Occlusion is not set

POV-Ray

POV-Ray is a free renderer which is available for Windows, Mac & Linux and other platforms.

Download & Installation

To install POV-Ray, download the latest version from the POV-Ray download site. Make sure you get the right version for your operating system. Installation instructions are included on the page.

Using POV-Ray as the Preferred Renderer

In the Renderer Settings dialog, choose POV-Ray as the Preferred Renderer. Choosing the POV-Ray tab in the Preferred Renderer will allow you to set various parameters for POV-Ray, including:

  • Path to POV-Ray executable. This is the location of the POV-Ray program on your machine.
  • POV-Ray environment variables. This allows you to manually set any POV-Ray environment variables. Refer to the POV-Ray documentation for more details.
  • POV-Ray version. Windows and Unix versions of POV-Ray have different commandline options. To be able to correctly invoke POV-Ray, JPatch must know which version is used. Choose Windows for the standard Windows version, Unix for all Unix versions, but also for the Cygwin version or the commandline version of MegaPOV on Windows.
  • Patch output (triangles or bicubic patches). By default, JPatch converts spline patches into triangular mesh for POV-Ray to render. As an experimental option, you can choose bicubic patches. Note, however, that POV-Ray will internally convert bicubic patches into a triangular mesh.
  • Mesh density. The higher this value is, the more triangles JPatch will generate per mesh. However, increasing the number of triangles in the model increases the time it takes to render the scene.
  • Antialiasing method. Without antialiasing, object edges can take on a “jagged” appearance. Antialiasing is done by breaking pixels into subpixels, sampling the subpixels, and assigning the pixel an average of the subpixels’ colors. By default method 1 is selected, but method 2 or none are also options.
  • Antialiasing level. This refers to how many subpixels a pixel should be broken into. 1 indicates no antialiasing, while 3 breaks the pixel into 9 (3×3) subpixels. Higher antialiasing level give better results, but increase rendering time.
  • Antialiasing threshold. Rather than apply antialiasing to each pixel, you can specify an amount a pixel must contrast with neighboring pixels before it is antialiased. Higher values will cause less oversampling (and faster rendering), but potentially leave more rendering artifacts.
  • Jitter amount. POV-Ray can add random jitter (slightly shifting each pixel), which can help hide aliasing. Higher values mean more jitter. Since jitter is random, it may be distracting to use high values in animations.

Preventing the POV-Ray GUI From Appearing

When POV-Ray is called in Windows, it will automatically cause the POV-Ray GUI interface to appear while the image is rendering, and then close down after the image is rendered. This is by design on the part of POV-Ray’s designers, and cannot be blocked. If this is an issue, you might want to consider using MegaPOV instead, which doesn’t have this behavior.

RenderMan Compliant Renderers

RenderMan refers to any render capable of parsing the RIB (Renderman Interface Bytestream). RIB is a scene description language, so a RenderMan compliant renderer only needs to be able to understand RIB. It does not mean that the renderer uses a particular rendering technology (i.e. the REYES scanline algorithm).

Despite the close association with Pixar's Renderman (PRMan) product, there are actually a large number of RenderMan compliant renderers. Examples of free RenderMan compliant renderers include Aqsis and Pixie. 3Delight is a commercial renderer, but free for non-commercial use.

Using a RenderMan Renderer as the Preferred Renderer

In the Renderer Settings dialog, choose RenderMan as the Preferred Renderer. Choosing the RenderMan tab in the Preferred Renderer will allow you to set various parameters:

  • Path to RIB-Renderer executable. The location of the renderer.
  • RIB-Renderer environment variables. Refer to your renderer’s documentation for details.
  • Output mesh as (Triangles/Quadrilaterals/Subdivision Surface/Bicubic Patch). You’ll have to experiment with these options to find which output format works best with your renderer.
  • Mesh density. The higher this value is, the more elements JPatch will generate per mesh, creating a smoother surface. However, increasing the density of the model also increases the time it takes to render the scene.
  • Pixel samples. The numper of samples per pixel (supersampling).
  • Pixel filter. The filter to apply to determine the final color of each pixel when multiple samples have been taken.
  • Shading rate. The REYES algorithm dices geometric primitives into grids of micropolygons whose vertices are shaded to create colors and opacities for output image pixels. (Saty Raghavachary - Rendering for Beginners, pg. 239). Shading Rate is the single most important control over image quality. It controls how large the maximum area of each micropolygon will be, in pixels. In most cases, the default of 1.0 is sufficient. For higher detailed images, 0.25 or 0.5 might be better.
  • Shading Interpolation. This parameter determines the apparent smoothness of the image. It takes a value of either “constant” which applies the same color across the entire micropolygon; or “smooth” which specifies that the interiors of large micropolygons (those that span several pixels) need to be interpolated from the values at the four corners, ironing out the faceting.
 
  jdp/renderers.txt · Last modified: 2005/11/28 09:49 by 80.120.175.84 (sascha)