From Kraytracing Wiki

Contents 1 Pestaña General 2 Render preset 3 Save/Load 4 Diffuse model 4.1 Raytrace 4.2 Photon estimate 4.3 Photon mapping 4.4 Cache irradiance 4.5 Path tracing 4.6 Caustics 5 GI mode 5.1 Independent 5.2 Time interpolation 5.3 Shared for all frames 6 Camera 7 Pixel order 8 Iris Shape 9 DOF target 10 Output files 11 Tone map 12 Header cmds / Tailer cmds

Pestaña General

Render preset

Esta lista contiene todos los presets predefinidos disponibles en Kray. Cuando eliges un preses los valores correspondientes son usados. Por ejemplo: si eleges el preset Medium, éste ajusta los valores predefinidos “medium” para photons, FG, Quality y todos los demás “sub-presets”.

Puedes elegir entre varios presets que hemos preparado para hacer tu trabajo más facil. Por favor, ten en cuenta que aunque hemos tenido en cuenta muchos detalles a la hora de elaborar los presets y que a menudo son un buen comienzo, no pueden funcionar en todas las situaciones.

Save/Load

El botón Save te permite guardar los ajustes de Kray en un archivo que luego podrás cargar en cualquier escena usando el botón Load.

Diffuse model

Éste es el modo principal de renderizado. Te permite elegir entre varios métodos explicados a continuación.

Raytrace

Éste modo puede renderizar la escena sólo con raytracing. Ésto quiere decir que la iluminación global no será calculada. Éste modo es útil principalmente con fines de pruebas. Asegurate de tener encendido los flags de raytrace en Lightwave render globals para que funcione adecuadamente.

Photon estimate

Photon estimate te permite elegir entre vários modos para previsualizar rápidamente la iluminación global en la escenan. Este modo sin FG se usa para un renderizado rápido.

Global filtered - renderiza los fotones que son disparados en la escena y los filtra.

Global unfiltered - renderiza una representacion de los fotones en la escena. A veces necesitas ver la densidad de fotones en la escena y éste modo es el mejor para verlos.

Precomputed - puede renderizar una representacion de las células de irradiación. Imita bastante bién la iluminación global de la escena. Se usa a menudo para ver el tamaño de las células en la escena y si la irradiacion es suave o no.

Precomputed filtered – es muy similar a precomputed. La única diferencia es que el modo filtrado fitra (blur) las células juntas. Éste renderiza una representación cercana a la iluminación global de la escena muy rápida y es el modo recomendado para ajustar la luz o las superficies. Éste modo también ofrece la opcion de sombras ray trace y renderizar causticas, lo que hace que sea la mejor representación del render final.

Photon mapping

Éste es el principal modo de renderizado en el motor de render Kray. Usa el mapeado de fotones con irradiance cached para renderizar rápidamente una imagen con iluminación global completa.

Cache irradiance

Cuando activas esta opción Kray puede usar caché de irradiación para acelerar el renderizado. Puedes leer mas sobre el caché de irradiación aquí . Cuando ésta opción está desactivada, Kray no usa ninguna caché de irradiacion y evalua cada pixel por separado. Esto da mayor calidad a las sombras a expensas del tiempo de renderizado.

Path tracing

Path tracing es una forma de trazado de rayo donde cada rayo es recursivamente trazado a lo largo de un trayecto hasta una fuente de luz, donde la luz contribución de la luz a lo largo del trayecto es calculada. Este trazado recursivo ayuda para solucionar la ecuación de la luz más precisa que trazado de rayo convencional. El inconveniente es que con un alto número de rebotes se vuelve más lento que el Mapeado de Fotonoes con caché de irradiacion.

Caustics

The Caustics check box will enable rendering of caustics in the scene. So whenever you want caustics to show up, don't forget to turn this on.

GI mode

To speed up rendering of image sequences Kray offers 3 different modes.

Independent

This mode will turn off GI sharing. It's used for testing or when you're rendering a single still.

Time interpolation

This mode can be used whenever there are moving objects and/or light sources in a scene. Kray will use illumination data from current frame and from previously rendered frames to speed up rendering. There are 2 basic ways of blending frames together. One is to take N (named Frames parameter in GUI) previous frames and count its average illumination.

y0=(x0+x1+x2+...+xn)/N

where y0 is interpolation result for current frame x0 is irradiance computed for current frame, x1,x2,...xn are irradiances from previous frames. Number of frames N is controlled by Frames parameter in GUI.

Another way is to take interpolated solution from previous frame and blend it with current frame with given proportions.

y0=y1*e+(1-e)*x0

y1 is result of interpolation from previous frame, parameter e in equation is labeled Extinction in GUI.

You can combine both methods. Then interpolation equation will look as follows:

y0=y1*e+(1-e)*(x0+x1+x2+...+xn)/N

Interpolation can be applied to Precached map (photon/light map after precaching) and Irradiance cache (final gather cache) or both.

Shared for all frames

If only camera is moving in your scene you should select this mode. You should specify a filename that Kray will use to save GI data into. If you don't specify any filename Kray will render into LightWave Image Viewer (only supported in LightWave 9.6+).

There are 3 different modes available:

Load: will load up the Gi data in the specified file. If the GI file doesn't contain enough data to accurately render global illumination it will compute new samples. This mode is often used when testing FG settings since it will only load save data and not save any new one into the file.

Save: will save computed GI data into the specified file when render frame is done.

Update: will load any existing GI data from file and on render end save new GI data into the same file. This mode speeds up rendering of animations dramatically. First frame will take some time to render, but all the consecutive frames will render much faster since they will compute GI only for the part of the scene that hasn't been calculated already. You should be careful with this mode when stopping and restarting rendering of animations. You should always use the same GI file to render complete animation. If you fail to do so you risk having sudden jump of light because every GI computation is a little different. So for example you rendered animation from frame 1-30 with one GI file and then frames 31-60 with another you will see a sudden jump of light in frame 31.

Reset File: Will clear the GI file on your disk so you don't have to go and manualy delete it.

Allow animation: will allow objects to move in the animation. Note however that GI will be computed only for the first frame. Other frames will use existing GI. This may cause artefacts around moving objects because indirect shadows will stay in place even though object moves. However direct shadows from lights will work just fine.

If you want to use full GI solution on animatable items use Time Interpolation mode

Camera

You can choose between using Lightwave camera or any of the built in cameras.

Lightwave: Will use currently selected Lightwave camera for rendering.

Spherical: Will render panoramic render mode, also called longitude/altitude. This is good for rendering out 360° panoramas.

Fisheye: panoramic render mode, also called light probe.

Texture baker: this mode allows to bake lighting on textures. Two options are available when this mode is selected. Object and UV name allows you to bake textures on object you want.

Pixel order

Pixel order allows user to select order of pixels appearing on screen. This option have influence on quality and rendering time if combined with Irradiance caching.

Scanline: will render pixels line by line starting at top.

Scancolumn: will render each row of pixels starting from left.

Random: will render pixels randomly.

Progressive: will progressively render the frame, updating image with better detail in each pass. This mode quickly shows a general preview of the lighting in the scene.

RenderWorm: will crawl through your image like a worm, revealing pixels underneath.

Frost: similar to RenderWorm but with a "frost" like effect.

Note that Pixelorders like Random or Progressive render slower than Scanline or Scancolumn.

Iris Shape

When DOF in Lightwave Camera properties is enabled you can use any image to represent Lens aperture shape. This can be a simple black and white image of even color image so R, G and B rays all can have different iris shapes.

DOF target

DOF target will let you choose object which Kray will use as a focus point. This option overrides Lightwave camera Focal distance.

Note: to see DOF in render you must choose FSAA or Random Antialiasing mode on Sampling tab.

Output files

Lets you specify name of an output file where Kray will write the image to.

Format: You can choose between several standard file formats. HDR lets you render into high dynamic range image which enables you to tonemap in post.

You can use special symbols in filename to change its format. See renderinfo command for details.

Tone map

Tone mapping is used to apply color transformations on the final image colors. Sometimes an image can contain a higher range of colors that can be displayed on a computer screen. Color mapping has the task of re-mapping the image values to be suitable for display purposes.

Kray can use the following methods of tone mapping:

Linear: Will not apply and correction to the image (it's the same as using Gamma with parameter : 1 and exposure : 1). This may produce too dark images since images need some gamma correction to be displayed correctly on monitors. It's also what is used by Lightwave and Fprime by default.

Gamma: This is a standard correction. The amount of Gamma correction is defined by Parameter field. Most monitors use gamma correction of 2.2 but this may produce washed out images. Generally speaking values between 1.4 and 1.8 work best with Kray (if you want to use Linear Workflow, you need to add Kray Quick Linear workflow plugin), but feel free to experiment.

Generally you can think of the parameter value of something that affects contrast. Low values (for example 1) will have a lot of contrast and the dark areas will be really dark and possibly losing a lot of detail. A high value (say 2 or 3) will make the image have far less contrast and the dark areas will be more visible.

Exposure affects light intensity in general. It works similar to exposing photos. Higher number means longer exposure thus brighter image, lower mean shorter and therefore darker image.

Another way to think of parameter and exposure is Exposure being the White point of the image and parameter the black point.

Exponential: will reduce the brightness of overexposed areas to pure white. Limits dynamic range of primary rays (those fired from camera). If a RGB component of a camera ray is bigger then value it is truncated. This is useful to make sure the over bright parts of an image are antialiased properly, for example the edges of polygons with Luminosity which is much higher than 100%.

LimitDR: by default limitdr is set to OFF (no dynamic range limit). LimitDR is done per camera ray, not per pixel. Therefore LimitDR command acts differently depending on when it's used. When its used before tonemap, Limitdr is applied before tone mapping and therefore any tonemaping like exposure or gamma can influence on how pixels are sampled (anti-aliased, etc.). When it's applied after tone mapping it will use current tonemapping settings for pixel sampling. Note that for Low Dynamic Range (LDR) images, it's dynamic range is always limited to output exposure.

HSV mode: when using tone mapping colors may loose their saturation. When this option is turned on Kray will try to keep saturation of colors instead of washing them out.

Header cmds / Tailer cmds

This are additional Kray “core” commands that do not have direct connection to buttons in GUI, but can instead be run by entering appropriate command.

You can find the list of all available commands here.