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--- user-guide:raytracing [2024/05/06 14:20] – thomas
+++ user-guide:raytracing [2025/01/08 21:36] (current) – updated MH
@@ Line 1: / Line 1: @@
 ====== Built-in Raytracers and their Options ======
-GroIMP contains a built-in raytracer (as opposed to external raytracers such as POV-Ray), which can utilize a set of different ray processors. This is the so-called "Twilight" renderer. Included are a the "standard ray tracer", a path tracer, photon mapping, a bidirectional path tracer, and processors for radiosity as well as metropolis light transport. The raytracers can be used for both light modelling within your RGG model as well as for rendering your scene. The following introduction covers the raytracing settings when used for rendering.
+GroIMP contains a built-in raytracer (as opposed to external raytracers such as POV-Ray), which can utilize a set of different ray processors. This is the so-called "Twilight" renderer. Included are a the "standard ray tracer", a path tracer, photon mapping, a bidirectional path tracer, and processors for radiosity as well as metropolis light transport. The raytracers can be used for both light modelling within your RGG model as well as for rendering your scene. The following introduction covers the raytracing settings when used for rendering. To use the Twilight renderer, select it as your <key>Render View</key>:
-**Twilight Renderer Options**
+{{:user-guide:3d_view.png}}
-{{:user-guide:raytracing_settings.png}}
-The raytracing settings for rendering can be customized under <key>Preferences --> Renderer --> Twilight</key>. The ray processor can be selected from the "Ray processor" drop-down menu. Note that not all of the ray processors work in all versions of GroIMP (in the current 2.1.3 version of GroIMP, only photon mapping is not working). When changing parameter values in the preferences, you always have to leave the field you changed with your cursor before closing the preferences window (just click in a different field) for your changes to take effect. Here is an overview of the different raytracing algorithms to choose from besides their relevant settings:
+When starting any of these renderers, your Scene will be rendered as an image using the current camera viewpoint. In case it takes too long, you can interrupt the process with <key>stop</key>. In some cases, this might not work and GroIMP dies, so be sure to save your project before experimenting with the renderers. When you moove the camera after the renderer has finished, the 3D View switches back to the default "interactive" OpenGL renderer.
-===== Standard ray tracer =====
-The Standard Raytracer option produces rather unnatural-looking
-images, as this algorithm ignores indirect lighting for diffuse materials
-and always calculates ideal reflections for reflective materials.
-However, the calculation with this option is quite fast.
-===== Path tracer =====
+More information:
-PT is a ray tracing method, with the help of which a global illumination simulation
+  * [[:groimp-platform:raytracing:raytracer_impl|Ray tracer implementation]]
-can be carried out.
+  * [[:groimp-platform:raytracing:raytracer_algo|Ray tracer algorithm]]
-Rendering with the Pathtracer option is qualitatively better compared to the standard ray tracer. The
+  * [[:groimp-platform:raytracing:raytracer_options|Ray tracer options]]
-images generated here support diffuse reflections very well, but can be noisy. Its options are located in the grey zone with no grouping label near the bottom of the Twilight renderer settings.
-<del>be noisy. The top field Pathtracing options contains the
-Number of paths property. This property is only evaluated if the
-Pathtracer MT has been selected as the ray tracing algorithm, and has a strong effect
-on the noise in the rendered image. The higher the value, the less
-noise the image contains, but the longer the calculation will take. The
-initial value of 25 is considered a good compromise.</del>
-The Recursion depth property determines how often light in the scene is
-scene is reflected back and forth during the calculation. The value 0
-would mean that all reflections and refractions are excluded. To obtain realistic
-images, it should be set to 6.
-<del>The Priority can be used to determine the resource consumption
-during the calculation can be determined. The high priority option
-option, all available resources are used for the calculation. The option
-medium priority option offers the option of loading the operating system
-to a limited extent. With the low priority option, the calculation is
-regularly paused, allowing work in the operating system in parallel with the
-calculation is possible.</del>
-In the <key>Antialiasing</key> method drop-down list, the user can select whether the image is to be
-is smoothed using super-sampling or whether no antialiasing is performed.
-The number of sampling passes can be controlled via the <key>Grid size of super sampling</key> field. It should be noted that the square of the input value will be used by the algorithm.
-===== Photon mapping =====
+Tutorials:
-<color #ed1c24>currently not working</color>
+  * [[:tutorials:starting_raytracer|Getting started with the Renderer]]
+====== Default Light Model ======
-===== Bidirecitonal path tracer =====
+The built-in raytacer also provides a light model to use in a rgg project.
-BTP is a path tracing process in which ray paths are generated by the camera as well as by all light sources in the scene and are linked together. BPT in GroIMP is controlled via 3 parameters.
-The <key>Max. eye path depth</key> and <key>Max. light path depth</key> parameters can be used to set
-the maximum number of vertexes on the eye path and light path respectively.
-A light path depth of 1 can be used to simulate the operation of a normal PT. Conversely, with an eye path depth of 1, only caustic events are displayed. Values smaller than 1 are not permitted.
-The parameter <key>Heuristic exponent</key> controls the calculation of the weighting factor w_st,
-reference the Steidelmüller 2008 report for further details.
-===== Radiosity =====
+Tutorial:
-The radiosity algorithm was developed in 1984 by Goral, Torrance, Greenberg and Battaile. It is a global illumination method that is ideal for diffuse reflecting surfaces. This corresponds well to reality, since
+  * [[:Tutorials:light-modeling-introduction| Introduction - A little bit of Theory ]]
-diffuse reflections are often encountered in practice, whereas completely reflective surfaces tend to be the exception.
+  * [[:Tutorials:light-modeling-first-steps| First steps ]]
-The basis for this algorithm is the law of conservation of energy. The aim is to achieve a balance between the radiant energy supplied by light sources and the radiant energy absorbed by all surfaces. This is achieved by calculating the specific illuminance for each surface. There are four important parameters to influence the quality of an image rendered using radiosity:
-<key>Hemicube size in pixel</key> determines the number of hemicube pixels of which a Hemi-Cube consists. The higher this value, the more precisely the light falling on a triangle is calculated.
-<key>Hemicube size in world coordinates</key> defines how large a Hemi-Cube is in the coordinate system of the scene.
-<key>Subdivision threshold</key>: After each calculation step, the color values of adjacent triangles are compared. If the difference is greater than this threshold, the triangles are subdivided for the subsequent calculation step.
-A lower value improves the color gradations between adjacent triangles, but increases the calculation time and memory consumption.
-<key>Subdivision depth</key> defines how many calculation steps are to be performed. The higher the value, the more precisely the image is calculated. However, this also increases the calculation time.
-===== Metropolis light transport =====
-MLT is a path tracing process in which randomly distributed initial paths on the image surface are mutated according to special rules until all image pixels are covered and the desired accuracy and mutation rate are achieved.
-The MLT raytracer in GroIMP is controlled via a separate parameter box
-in the raytracing options.
-The user has the option of selecting the mutation strategies to be used via checkboxes. They can also specify the number of initial paths in the <key>Count of seed paths</key> field. The most decisive parameter for the quality of the final image is the <key>Count of mutations per pixel</key> field, which determines the average target number of mutations per image pixel. It is important to note that the renderer
-tries to achieve this average value for all pixels of the image. For scenes that are mostly empty (e.g. an object floating freely in space without any surrounding elements), the pixels highlighted with an object are frequented correspondingly more frequently by the algorithm.
-As the bidirectional ray tracer is used in advance, its parameters also determine the length of the paths also determine those of the MLT raytracer.
-More information:
-  * [[:groimp-platform:raytracing:raytracer_impl|Ray tracer implementation]]
-  * [[:groimp-platform:raytracing:raytracer_algo|Ray tracer algorithm]]
-  * [[:groimp-platform:raytracing:raytracer_options|Ray tracer options]]
-Tutorials:
-  * [[:tutorials:starting_raytracer|Getting started with the raytracer]]
 ====== GPUFlux ======
@@ Line 90: / Line 38: @@
 Tutorials:
   * [[:tutorials:setup-gpuflux-for-eclipse|How to setup GPUFlux in Eclipse]]
-  * [[:tutorials:use_fluxmodel|how to use a FluxModel]]
+  * [[:tutorials:use_fluxmodel| How to use the FluxModel ]]
-====== Default Renderer ======
+  * [[:Tutorials:basic-spectral-light-modeling| Spectral light modelling ]]
-By default GroIMP provide a real-time rendering view based on OpenGL.
 ====== Flux Renderer ======