Visualization Guide
Visualization Guide
Visualization Guide
Visualization Guide
Visualization Guide
Visualization Guide
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In most cases, higher image quality is achieved at the expense of longer processing time — with a little effort you can learn how to get adequate quality in a reasonable amount of time.
The Stroke Tolerance, Antialiasing Grid Size and Ignore Open Elements And Text settings affect rendering quality.
Lighting types and Surface material definitions can be simulated with a high degree of realism.
You can define all settings for rendering from the Rendering Setup dialog box (Settings > Rendering > Setup), which also lets you save your rendering setup parameters for use in other designs. This is useful for creating setups for different levels of accuracy/finish.
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These same settings can be defined in their individual dialog boxes, such as the following:
Rendering Settings dialog box (Settings > Rendering > General)
Rendering View Attributes dialog box (Settings > Rendering > View Attributes)
Ray Tracing dialog box (Settings > Rendering > Ray Tracing)
Radiosity dialog box (Settings > Rendering > Radiosity)
Particle Tracing dialog box (Settings > Rendering > Particle Tracing)
Any settings that you change in the Rendering Setup dialog box, and apply to the view(s), are reflected in the individual dialog boxes, and vice-versa. Using the Rendering Setup dialog box simplifies the setting up process because all settings are readily accessible from the one dialog box.
Shadow settings for Phong rendering are controlled in the Rendering Settings dialog box (Settings menu > Rendering > General), or the General tab of the Rendering Setup dialog box.
Phong Shadow Filter Size determines the softness of shadows — larger values produce softer shadows. Its value describes the number of adjacent pixels to look at in the shadow map. Zero or one would produce hard shadows; two or three would produce softer shadows.
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A Large Phong Shadow Filter Size results in softer shadows. | |
Phong Shadow Tolerance determines how close objects can be to cast shadows on each other, and is used to prevent surfaces from casting shadows on themselves. The default value .02 is usually sufficient to prevent self-shadowing. Large Shadow Tolerance values can cause inaccurate shadow generation.
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Phong Shadow Tolerance. The default settings are usually sufficient. | |
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Phong Shadow Tolerance. A large Phong Shadow Tolerance may cause inaccurate shadows to be generated | |
 | If the shadow tolerance is too large, objects may not cast shadows on other objects that are too close. If it is too small, the objects might shadow themselves, causing a rippled appearance across the surface. |
Even on fast systems, high-resolution ray traced images take some time to generate. The following options in the Ray Tracing dialog box help reduce the time required to produce photo-realistic ray traced images:
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Ray Tracing dialog box | |
Quick Display allows a ray traced image to be previewed quickly, letting you stop processing (with a Reset) if the image needs fine tuning.
| Multiple images can be ray traced sequentially without user intervention. See General Procedure for Rendering Multiple Images. |
| As a general rule, to save time, test renderings should be done in small views or fences. Large views, or images saved to disk, should only be rendered after you are satisfied with the initial results. |
There is a key-in that can be used by advanced Visualization users to improve ray tracing performance in certain situations.
This key-in, RAYTRACE SET CONTRIBUTION <value>, sets the minimum contribution a reflected or transmitted ray needs to have before that ray will be computed.
In ray tracing calculations, the contribution of a ray is cumulative from the eye. Take, for example, a ray from the eye that sees an object having a reflective value of 0.6. The contribution of the ray reflected from this object would be 0.6. If that reflected ray now sees an object that has a transparent value of 0.3, the contribution of the ray transmitted from the new object would be 0.6 * 0.3 = 0.18. If the minimum contribution was set to 0.2, this transmitted ray would not be computed, since it would be considered insignificant.
Values that may be used for this key-in range from 0.0 to 1.0. A value of 0.0 (the default) indicates that all rays are significant and will be computed, while values near 1.0 indicate that almost no reflected or transmitted rays are significant, and most would be ignored. Typical non-zero values would range between 0.1 and 0.001. Submitting this key-in without a value will display the current value in the status bar.
When rendering a view, you can choose from Normal, Antialias and Stereo shading types.
The view is shaded normally.
Reduces the jagged edges (jaggies) that are particularly noticeable on low-resolution displays. The additional time required for antialiasing is especially worthwhile when saving images for presentation, publication, or animated sequences.
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Antialiased (left) compared to not antialiased (right). | |
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Magnified view of top edge when antialiased (left) and not antialiased (right). | |
An option menu, in the Rendering Settings dialog box, lets you set the value of Antialiasing Quality. This same setting is present also in the Ray Tracing dialog box's Antialiasing Settings section. Choosing from any of the preset options — Very Low, Low, Medium, High, Very High — automatically sets the values for Antialiasing Grid Size. Choosing Custom lets you manually edit the Antialiasing settings.
Antialiasing with standard rendering modes is done by rendering the model several times and combining the images into one image. Antialiasing quality is determined by the Antialiasing Grid Size setting, which can be set automatically with the Antialiasing Quality settings of Very Low, Low, Medium, High, Very High. Alternatively, you can input the value manually if you choose Custom.
MicroStation's Ray Tracing render mode uses an adaptive antialiasing technique that samples each pixel. The number of samples taken is determined by the Quality setting, which sets the minimum and maximum samples. Antialiasing for Ray Tracing is performed as follows:
A small number of initial samples is taken in a pixel. The number of initial samples is determined by the Samples Min setting in the Ray Tracing dialog box (Antialiasing Settings).
The degree that the samples vary from each other is determined.
If the variance exceeds the Contrast Threshold, another sample is taken and the variance is re-evaluated.
This procedure is repeated until the variance between the samples is acceptable, or until the maximum number of samples is reached. The maximum number of samples is determined by the Samples Max setting in the Ray Tracing dialog box (Antialiasing Settings).
When done, all the samples are combined into a final pixel value.
You can set the minimum and maximum samples manually, by setting Quality to Custom in the Antialiasing Settings area of the Ray Tracing dialog box. Generally, selecting one of the preset Quality settings, which presets the minimum and maximum samples settings, will cover most situations.
Renders a view with a stereo effect that is visible when viewed with 3D (Red/Blue) glasses. Stereo shading takes twice as long as Normal because two images, one each from the perspective of the right and left eyes, are rendered and combined into one “color coded” image.