xzzy.org

The Yafray Exporter interface.

This page attempts to explain what all the buttons and spinners on this tool can do.

Rollout: Global Illumination (GI)

This section controls the advanced rendering features of yafray. These features are generally very slow to render, however, they also offer the most realistic lighting. These options are quite hard to tune, especially for a novice.

Hemilight - A very simple method of GI, it ignores the surface properties of objects in the scene and instead only calculates whether a given point is in shadow or not. Samples reflects how many passes to do with the hemilight, lower values render faster but produce very noisy images. Higher values equal higher quality. 20-30 is decent for test renders, 100 or so is sufficient for final renders.
Pathlight - The "big boy" version of GI. This light system takes light/color information from the background and any objects the ray of light hits on it's way through the scene, and "deposits" that color on any surfaces it encounters. Using this alone does NOT tend to illuminate the full scene.

Samples - Number of rays to direct at each pixel. Use low values for test renders, 16 is a good default. Raise for final renders (256 or higher).
Power - Intensity of the light.
Depth - The "strength" of each ray. This sets how many objects a ray of light can bounce off before becoming too weak to illuminate anything. If you use a Global Photon Light, you will want to leave depth at 1.
Use Cache and Cache Size - This is an optimization method specific to Yafray. Generally you will want it on.. it dramatically reduces render times. Cache size controls how fine to make the cache. Lower values are higher quality.
Search - For any given pixel, the raytracer searches in a given radius for bouncing rays of light to determine what color that pixel will be in the final scene. Search controls this feature. Small values render faster, but result in lower quality shading. Generally 30-70 is good, but this value will be scene-specific.

Global Photon Light - A close buddy of the Pathlight. For the most part, if you use one, you will want to use the other. What this does is shoots rays of light from all the source in your image, producing shadows and delivering indirect light to unlit surfaces. This is what lights your scene.. the Pathlight is used to calculate coloring.

Photons - The number of "light rays" to send into the scene. This number is divided to distribute evenly from every light in your scene. Higher values take longer to render, but produce smoother lighting. There are diminishing returns however, there is a point where all it does is increase render times.
Radius - When a photon hits a surface, this controls the radius of the effected area. Small values make tiny intense dots, big values are softer and fuzzier.
Depth - How many times a ray can bounce before extinguishing. 2 is a minimum for a test render, you won't start to see transparency however until you hit a depth of 4 or go higher. Go too high however and render times skyrocket.
Search - When the renderer is deciding what color a given pixel should be, it will use this search radius to look for nearby spots that a photon hit. It will then average whatever it finds together to get it's final result. Bigger values will generally make shading smoother, but if you go too big the lighting starts to suffer. Low values will result in very blotchy lighting (think polka dots).

2D Filters

2D Filters are "post-processing", in that they take the resulting render and run the filter before saving the file. The downside to this is that the filter may not be suitable for the scene because it has no knowledge of the depth. The upside is that it's fast, and in situations that it works looks pretty decent.
The Depth of Field filter tries to emulate a camera, causing nearby or faraway objects to be blurry, or both. What this results in in practice is that the bottom of the image is taken to be "near" and the top is "far".

Focus - The size of the "in focus" part of the scene. 12.5 makes about the middle 50% of the image in focus.
Near Blur - Controls how blurry the near field is.
Far Blur - Controls how blurr the far field is.
Scale - Sets a scale for "in focus" areas of the scene. Areas that are not in focus will be "pushed" away, simulating a fish-eye lens type of effect.

Backgrounds

Backgrounds are analogous to "skyboxes" used in most 3d games. That is, it is an image or color wrapped around the world giving the illusion of a sky without requiring models to show it. The main difference for rendering software is that they use backgrounds to supply environmental lighting. The effect this will have on a scene is it lends subtle shading on objects that give a much more realistic appearance. On shiny objects, the background can be directly reflected which has a similar influence on the realism.
Image - Allows you to select an image (TGA or JPG format) to use as the background. It is wrapped around the scene as a sphere. The Power spinner controls the brightness of the image in the scene.
Constant - Sets a constant single shade of the chosen color as the background.

Rendering

This rollout controls a few of the global options for the final render, stuff that doesn't fit specifically in any other group.

Light Multiplier - A value multiplied directly to any light source in the scene. In the conversion from Gmax to Yafray, the scales don't always match up and you may find yourself in a situation where too little or too much light is produced. This multiplier lets you tweak this on a global scale.
AA-Passes - Controls how many runs of anti-aliasing to do after the scene is rendered. Values much over 5 have negligible effect on the scene. AA does increase render times, but not significantly.
Raydepth - How many times the light from a light source can reflect before it is extinguished. This value is quite important for rendering reflections and transparency.. if you don't set the value high enough the light will die before it reaches the camera. 2 is good for test renders with no reflections. 4 is the minimum for transparent scenes.
bias-Value - No clue. I just realized I've never played with this value. Maybe I'll figure that out sometime.

The Yafray Material

With v09 of my exporter script, I created a material plugin for gmax that offers a streamlined interface into configuring shaders for yafray. Old scenes should still export like they used to, I have maintained the backwards compatiability, however this new material is now the "supported" option because it gives a much more straightforward translation from gmax to yafray.
Once the script is installed and you press the "New" button in the material editor, there will be an option for the Yafray Material. Once you select that you should see a scene that looks like the image on the left there.
Base Properties - These settings control basic features of the shader, from the color, to more advanced features like shinyness and transparency. Each field has a label for what the associated color picker controls, and a checkbox. The checkbox controls wether that feature is exported to be rendered.

Color - Controls the base diffuse color of the object. Note that if you want to use textures on this object, you will probably want to disable the checkbox for this field.. else whatever color shows here will soak through the texture in the render.
Specular - Controls the color of specular effects on the object.
Reflected - Controls the color of objects showing in the reflections on this object.
Transmitted - Controls what color light that passes through this object ends up being colored.
Specular Hardness - Sets the harshness of specular effects on the object. Low values make for very fuzzy hilights, high values gradually sharpen them.
Inded of Refraction - A measure of what happens to light when it hits this object, controlling how much light is bent from it's original course. Low values allow light to pass progressively closer to it's original path. 1.52 is equal to glass. For most practical purposes anything above 20 will be solid, resulting in a very shiny object.

Textures allow you to apply various maps to the object. Each map has a checkbox enabling or disabling that texture, a spinner for controlling how strongly to apply the texture, and a button that will allow you to specify which image to use.

	Rollout: Global Illumination (GI) This section controls the advanced rendering features of yafray. These features are generally very slow to render, however, they also offer the most realistic lighting. These options are quite hard to tune, especially for a novice. Hemilight - A very simple method of GI, it ignores the surface properties of objects in the scene and instead only calculates whether a given point is in shadow or not. Samples reflects how many passes to do with the hemilight, lower values render faster but produce very noisy images. Higher values equal higher quality. 20-30 is decent for test renders, 100 or so is sufficient for final renders. Pathlight - The "big boy" version of GI. This light system takes light/color information from the background and any objects the ray of light hits on it's way through the scene, and "deposits" that color on any surfaces it encounters. Using this alone does NOT tend to illuminate the full scene. Samples - Number of rays to direct at each pixel. Use low values for test renders, 16 is a good default. Raise for final renders (256 or higher). Power - Intensity of the light. Depth - The "strength" of each ray. This sets how many objects a ray of light can bounce off before becoming too weak to illuminate anything. If you use a Global Photon Light, you will want to leave depth at 1. Use Cache and Cache Size - This is an optimization method specific to Yafray. Generally you will want it on.. it dramatically reduces render times. Cache size controls how fine to make the cache. Lower values are higher quality. Search - For any given pixel, the raytracer searches in a given radius for bouncing rays of light to determine what color that pixel will be in the final scene. Search controls this feature. Small values render faster, but result in lower quality shading. Generally 30-70 is good, but this value will be scene-specific. Global Photon Light - A close buddy of the Pathlight. For the most part, if you use one, you will want to use the other. What this does is shoots rays of light from all the source in your image, producing shadows and delivering indirect light to unlit surfaces. This is what lights your scene.. the Pathlight is used to calculate coloring. Photons - The number of "light rays" to send into the scene. This number is divided to distribute evenly from every light in your scene. Higher values take longer to render, but produce smoother lighting. There are diminishing returns however, there is a point where all it does is increase render times. Radius - When a photon hits a surface, this controls the radius of the effected area. Small values make tiny intense dots, big values are softer and fuzzier. Depth - How many times a ray can bounce before extinguishing. 2 is a minimum for a test render, you won't start to see transparency however until you hit a depth of 4 or go higher. Go too high however and render times skyrocket. Search - When the renderer is deciding what color a given pixel should be, it will use this search radius to look for nearby spots that a photon hit. It will then average whatever it finds together to get it's final result. Bigger values will generally make shading smoother, but if you go too big the lighting starts to suffer. Low values will result in very blotchy lighting (think polka dots).
	2D Filters 2D Filters are "post-processing", in that they take the resulting render and run the filter before saving the file. The downside to this is that the filter may not be suitable for the scene because it has no knowledge of the depth. The upside is that it's fast, and in situations that it works looks pretty decent. The Depth of Field filter tries to emulate a camera, causing nearby or faraway objects to be blurry, or both. What this results in in practice is that the bottom of the image is taken to be "near" and the top is "far". Focus - The size of the "in focus" part of the scene. 12.5 makes about the middle 50% of the image in focus. Near Blur - Controls how blurry the near field is. Far Blur - Controls how blurr the far field is. Scale - Sets a scale for "in focus" areas of the scene. Areas that are not in focus will be "pushed" away, simulating a fish-eye lens type of effect.
	Backgrounds Backgrounds are analogous to "skyboxes" used in most 3d games. That is, it is an image or color wrapped around the world giving the illusion of a sky without requiring models to show it. The main difference for rendering software is that they use backgrounds to supply environmental lighting. The effect this will have on a scene is it lends subtle shading on objects that give a much more realistic appearance. On shiny objects, the background can be directly reflected which has a similar influence on the realism. Image - Allows you to select an image (TGA or JPG format) to use as the background. It is wrapped around the scene as a sphere. The Power spinner controls the brightness of the image in the scene. Constant - Sets a constant single shade of the chosen color as the background.
	Rendering This rollout controls a few of the global options for the final render, stuff that doesn't fit specifically in any other group. Light Multiplier - A value multiplied directly to any light source in the scene. In the conversion from Gmax to Yafray, the scales don't always match up and you may find yourself in a situation where too little or too much light is produced. This multiplier lets you tweak this on a global scale. AA-Passes - Controls how many runs of anti-aliasing to do after the scene is rendered. Values much over 5 have negligible effect on the scene. AA does increase render times, but not significantly. Raydepth - How many times the light from a light source can reflect before it is extinguished. This value is quite important for rendering reflections and transparency.. if you don't set the value high enough the light will die before it reaches the camera. 2 is good for test renders with no reflections. 4 is the minimum for transparent scenes. bias-Value - No clue. I just realized I've never played with this value. Maybe I'll figure that out sometime.