MicroStation CONNECT Edition Help

Ray Tracer Tab

General Section

Setting	Description
Output Channels	Allows you to choose a rendering output. When enabled, the render engine will render a separate channel for the selected channels. When the render completes, you can use the save option from the render dialog and the selected channels will be saved to files. Note: Color & Alpha will always be rendered while ray tracing and is always enabled for all ray tracing render setups. Channels marked in red in the below image are not supported by Path Tracer:
Reflection	Determines how the reflection rays are traced in a raytraced render. Reflection Depth - This setting determines the number of times a reflection is seen. For example, imagine a kaleidoscope that reveals geometric patterns using a set of mirrors. Top: Reflection Depth = None \| Bottom: Reflection Dept = Four
Refraction	Determines how the refraction rays are traced in a raytraced render. Refraction Depth - Controls the number of transparent surfaces a refraction ray travels before it is terminated. A modeled glass windowpane having some thickness would consist of two transparent surfaces, and a refraction depth setting of 2. Similarly, for a ray to travel through an accurately modeled glass bottle would require a refraction depth of 4. Setting up two bottles in line the refraction depth would need to be 8 to see through both bottles. Adding a liquid would add two more transparency planes meaning to see through two bottles with liquid refraction depth would need to be 12. If you have refraction depth set too low will result in black pixels where the refraction ray is terminated early. In the below renders you can see the effect of refraction depth settings on renderings. In this test case to avoid the early termination of refraction rays with resultant black pixels you would need a refraction depth of 12 or higher. Top to Bottom : Refraction Depth = 5,8,12,16
Stroke tolerance	Controls the number of triangles curved surfaces are broken into before being rendered. Smaller values produce smoother results but at the expense of render time. Stroke Tolerance may be defined in pixels or physical units. Stroke tolerance may be set as a distance in meters or pixels where the latter is used the results will be view-dependent, that is if the camera is closer to curved surface at render time will result in finer stoker tolerance than when the camera is further away. Left to Right: Stroke Tolerance = 5, 0.5, 0.1
Depth of Field	If enabled camera blur will be used to mimic the depth of field effect. This is done as a post-process with very little overhead. The point that is in focus is based on the focal distance and is the distance from the eyepoint to the camera target.
Blur	Shows the amount of blur applied when the Depth of Field is enabled values can be above 100%.
Blur Rendering Method	Options are Distributed ray-tracing, Hybrid 2.5D, and Fast Hybrid 2.5D. Distributed RayTracing - Used to render Motion blur and depth of field. This method is a physically accurate approach that converges towards the exact solution as the number of samples per pixel increases. Hybrid 2.5D - is a method that is totally noise-free and much faster to compute. Computation time is not very dependent on scene complexity. Note: Hybrid 2.5D is not compatible with network rendering, due to the way this algorithm works. The distributed ray-tracing blurring method will be enforced when you enable network rendering. Fast Hybrid 2.5D - Uses a new algorithm for depth of field generation. It is based on image blur like Hybrid 2.5D but uses a faster color spreading algorithm and works in conjunction with distributed ray tracing. Usually, several passes are required to get all the distributed raytracing noise smoothed out. Systematic object anti-aliasing is incorporated inside Fast Hybrid 2.5D. Therefore, anti-aliasing settings become linked to the depth of field settings. This means that only systematic anti-aliasing becomes available, and the minimum number of rays per pixel becomes equal to the number of the depth of field passes (changing either of them changes both values).
Camera Projection	Options are From View, Spherical and Cylindrical. For rendering panorama images, you can use cylindrical or spherical with recommended aspect ratio of 2:1 for example 5000 x 2500 or 10000 x 5000 pixels.
Shadows	If selected shadows are rendered.
Ignore Default Lighting	If enabled, will ignore default lighting.
Ignore Open Elements and Text	If enabled, will prevent text and open elements from being rendered, our default is to have this option enabled.
Render Geometry Outside View	If enabled, will make sure the entire scene is sent to the render engine. If not enabled some geometry behind the camera may not be rendered. Geometry that is crossed by the camera's view frustrum will always be included.
Compute Physically Accurate Caustics	If enabled, will cause the render engine to render caustic effects. The accuracy of the caustics can be improved by increasing the number of Caustic Photons used. Top: Without Caustics \| Bottom: With Caustics
Render PBR materials as Legacy Equivalent	If enabled, will convert PBR materials to legacy and send to the ray tracer at render time.

Anti-aliasing Section

Anti-aliasing is a method used to reduce stair step effects (pixelization) on the edges of objects or textures. Aliasing appears along the border of objects, as well as alongside sharp color transitions in texture maps. Object anti-aliasing improves the smoothness of the picture by re-sampling each pixel several times.

Setting	Description
Anti-aliasing Strategy	Let's you control how the different anti-aliasing samples are weighed into the final pixel: Automatic - renderer will use the most adapted strategy for each scenario, namely the Sharp method for rendering stills, and the Soft method for rendering animations. Crisp - renderer will generate images with the sharpest details, but it may require to manually increase the number of sub-rays to eliminate noise in the renders. Sharp - ideal for still renders. It produces relatively sharp results while efficiently eliminating noise. Soft - a slightly blurrier (and consequently less noisy) method of filtering, usually most suitable for rendering animations. Blurred - produces blurry results that could be suitable for certain types of animations.
Anti-aliasing Min Samples	Controls the number of rays initially sent inside a super-sampled pixel. If the render engine decides that more anti-aliasing rays are required, it will keep sending new batches of rays until the total number of rays sent for that pixel reaches the Anti-aliasing Max Samples setting.
Anti-aliasing Quality	Controls how the render engine decides whether more rays are required or not, after having computed the first batch. The higher the setting, the more often sub-rays will be sent into pixels. This is a color-based anti-aliasing: if the color difference between the current pixel and its neighboring pixels is smaller than the threshold (Contrast setting), then anti-aliasing is applied. In other words: increasing this value makes the renderer more sensitive to color differences around pixels to determine if new sub-rays must be computed. It is applied to all pixels in the scene.
Geometry Quality	This is an edge-based anti-aliasing setting. It checks object IDs and depth. It makes the renderer more sensitive only to geometry differences around each pixel. So, for example if you set it to 100%, and the Contrast to 0%, then only the edges of objects will receive more rays. Clouds and smooth parts of 3D objects won't get any anti-aliasing (even wavy water surfaces). Conversely, if you set the Contrast to 100%, then the Geometry setting won't increase the visual quality of the render. The Geometry setting is a way of doing manual optimization, to avoid recomputing sub-rays where it's not needed. Obviously, the higher these three settings, the better the quality, but at the expense of longer the render times. In the below image the left render is with anti-aliasing off and the right render is with Exterior Extreme using Min Samples 4, Max Samples 32 Anti-aliasing Quality 90%. Top: Anti-aliasing = Off \| Bottom: Anti-aliasing = Extreme
Regular sub-pixel sampling	If enabled, the rays in the first batch of sub-rays are placed the same for all the pixels in the image. If not enabled, sub-rays are cast randomly in each pixel.
Texture filtering	Controls the amount of automatic blurring that is applied to materials in the scene. This setting lets you control the overall "sharpness" of the render. For optimal results, this setting should be used together with the Anti-aliasing strategy setting (see above). Texture filtering is enabled by default from the Interior Better and Exterior Better render setting on up through Extreme render presets. In the case of texture maps, the software automatically generates lower resolution versions of the images and uses them instead of the original resolution texture maps when they are seen from a distance. Note: When rendering animations, it is recommended that you use some amount of texture filtering.

Global Illumination

In this section you can change various settings that affect the global illumination used by the ray tracer including the global illumination model used. MicroStation's VUE rendering engine uses three lighting models. Global Ambience, Ambient Occlusion and Global Radiosity.

Each point of the scene receives light from the sun, the sky as well as from the environment (sky and surrounding objects). The different lighting models differentiate themselves by the way they estimate the amount of light coming from the environment.

Setting	Description
Global ambience	Considers the color of the sky in all directions. As a result, parts of the scene that look towards blue sky will take on blue shades of light, whereas other parts looking towards red sky will take on red shades of light.
Ambient occlusion	Considers each point on the sky dome as a little source of light. Rays are traced towards each one of these lights, to see whether a neighboring object is occluding the light or not.
Global radiosity	Propagates light in the scene, instead of propagating shadows as the ambient occlusion model. With this model, objects that are exposed to light will reemit some of that light in all directions, according to the optical properties of their surface. Light will thus "bounce around" repeatedly in the scene, as it would in real world. As a result, each point in the scene receives light from all the other objects in the scene. Note: When using radiosity, materials containing luminosity or that have non-standard (60:40) proportions of ambient diffuse light may cause undesirable lighting effects. These materials may have to be adjusted to achieve the desired effect. Indirect Skylighting - VUE will evaluate the amount of skylight that is received by each object and cast back onto the other objects in the scene. If this option is not selected, the Ambient light color will be used instead of computing the indirect contribution of the skylight. Indirect Atmospherics - Considers the light being reflected from clouds onto the objects in the scene when calculating indirect lighting. Optimize for outdoor rendering - VUE will assume rendering an infinite outdoor landscape. This option will lower the order of indirect radiosity calculations, effectively ignoring highly indirect lighting contribution, thus producing a faster and more robust render. Albedo Scale - Albedo is the measure of the diffused reflection of solar radiation out of the total solar radiation received by a surface. It corresponds to the diffused reflective strength of a surface. Albedo scale allows you to globally scale diffused reflectivity of all surfaces in the scene. Note: For physically correct rendering, albedo scale should be set to 100%. This will ensure that input reflectance values are not be scaled down at shading time. It is especially important when using PBR materials, which are generally calibrated in a physically correct way.
Advanced Effect Quality	Allows you to customize the indirect lighting settings to fine tune the way indirect lighting is evaluated in your scene. Note: The settings in this section should rarely need to change from the presets and we recommend using the presets before attempting fine tuning with these settings. Indirect Lighting Samples - Controls the typical number of illumination samples that are processed to evaluate indirect lighting at each point in the scene. Harmonic Distance Quality - Controls the way VUE evaluates the distance to the objects in the vicinity of a point in the image, and the way this distance influences the evaluation of the indirect lighting. Alignment Quality - Controls the way VUE evaluates the alignment of the different lighting samples in space, and the way this alignment influences the evaluation of the indirect lighting. Continuity Quality - Controls the way VUE evaluates the orientation of the different lighting samples in space, and the way this orientation influences the evaluation of the indirect lighting. Contrast Quality - Controls the way VUE evaluates the contrast between the different sources of lighting and materials, and the way this contrast influences the evaluation of the indirect lighting. Jittering - Controls the way the lighting samples are distributed in space. There are two options in the list: Reduced pulsation - Distributes the samples in such a way as to reduce the low frequency pulsation that is typical of animation using adaptively sampled indirect lighting. This option is particularly useful when creating animations. Standard - Ensures a better statistical distribution of lighting samples throughout the scene Bucket size - Controls the base grid for the evaluation of the indirect lighting. You will have at least one sample for each bucket. Reducing the bucket size will increase the accuracy of the indirect lighting evaluation but will also slow down renders quite significantly. Show samples - If enabled, the points at which the indirect lighting is evaluated will be displayed in the final picture as reddish pixels. Adaptive Sampling - If enabled, VUE will use several complex criteria to evaluate the frequency and accuracy at which the indirect lighting must be evaluated. If disabled, the indirect lighting will be recomputed entirely at each sample. This will result in very long render times and it is strongly advised that you do not disable adaptive sampling.
Indirect Illumination	The Custom radiosity photon map options let you control the photon map that is used for the evaluation and rendering of radiosity. Radiosity photons - Controls the total number of photons that are sent into the scene in order to evaluate the radiosity illumination. Maximum photon tracing level - This setting controls how many times the light is bounced inside the scene. Higher values will result in a more accurate evaluation of the radiosity illumination, but also a longer processing time. Number of gathering photons - This setting controls the number of photons that are used to evaluate the illumination at each point. Maximum gathering radius - This setting controls the maximum distance to a photon beyond which the influence of the photon will be ignored in the computation of the radiosity illumination.
Custom caustic photon map options	The settings in this frame are identical to the ones in the radiosity photon map frame, except they apply to the caustic photon map instead of the radiosity photon map.