Visualization Guide
Visualization Guide
Visualization Guide
Visualization Guide
Visualization Guide
Visualization Guide
|
You can assign material definitions — attributes related to color, texture, transparency, and finish — to surfaces. Definitions may be assigned on a level/color basis, or attached as an attribute to an element, or to an individual face of a SmartSolid. Material definitions attached as attributes to elements/surfaces take precedence over assignments by level/color.
Materials are defined in a material palette (.pal) and may include a pattern map, a bump map, or both.
A material assignment table (.mat) assigns a material to elements in the design that reside on a specified level(s) and with a specified color(s). All elements on the same level with the same color have the same material characteristics, unless individual elements have materials attached to them as attributes.
Type of File: |
Suffix/Extension: |
Stores: |
To modify: |
Usually referred to by: |
|---|---|---|---|---|
Material palette file |
.pal |
Material definitions |
From the Settings menu, choose Rendering > Materials. Alternatively, in the Apply Material tool settings, double-click the material preview box to open the Material Editor. |
Multiple DGN files |
Material assignment table |
.mat |
Assignments to levels and colors in design |
In the Rendering Tools tool box, select the Apply Material tool. Alternatively, select Material > Assign in the Material Editor dialog box, or edit the assignment manually in the palette tree. |
One DGN file |
 | Many sample material definitions are supplied. If you do not plan to create your own material definitions, but want to apply existing material definitions to elements, see To assign materials to elements. |
When defining materials for your models, settings in the Material Editor dialog box let you define how the surfaces react with light in the scene. In order to use correctly the various material settings, it is important to understand how they affect the interaction of light rays with objects in your models. The diagram below shows the various possibilties when a light ray strikes an object.
 |
Legend:
1 — Light source
2 — Diffuse (percentage of light that is randomly dispersed in all directions).
3 — Specular (percentage of light reflected in the mirror direction) and Reflect (percentage of light that is visible in the mirror direction).
4 — Surface Normal
5 — Refract (angle that light “bends” as it passes through an object).
6 — Translucent (percentage of light that passes through an object and then is dispersed randomly in all directions on the back side of the object).
7 — Transparent (percentage of light that passes through the object).
8 — Finish (roughness of the surface, which controls the falloff of highlight on a surface).
In reality, all objects absorb some amount of light. That is, not all the light that strikes an object is reflected or transmitted. Similarly, when you define materials in your models, they should not be greater than 100% efficient. This is important, in particular, for materials that are to be used in photo-realistic images. For these materials, the following formula should be used:
Efficiency = Diffuse + Translucency + Specular + Transparency <= 100
Using the Efficiency lock, in the Material Editor's advanced mode, you can select an Efficiency value, which is maintained as you modify the above settings. That is, if you modify a setting for Diffuse, Translucency, Specular, or Transparency, changes are made also to the remaining three settings to maintain the Efficiency setting.
For increased realism, a pattern map can be included in a material definition. Pattern maps are raster images (patterns) that are “mapped” to selected surfaces in the design file, as determined by the material assignments.
You can map an image of a carpet, for example, to a shape in the design file that denotes the floor. When rendered, the shape takes on the appearance of the carpet.
(Phong shading, Ray Tracing, Radiosity and Particle Tracing only) Material definitions can include a bump map, which can be any image (even the same image as that used for a pattern map). Brighter portions of the image are interpreted as high points, or bumps, and darker areas are interpreted as depressions or dents (this can be inverted in the bump map settings.)
Bump maps can be used with pattern maps to simulate realistic surfaces. For example, a material definition can use a bricks and mortar pattern map, along with the equivalent bump map, to produce realistic bricks and mortar.
 | |
From left to right: Element with no material definition, with pattern map, with bump map, with both pattern and bump map. | |
Rendering relies on the reflection of light off surfaces in the design file. Material definitions include settings for various properties that affect the way that lighting is treated. Using the Material Editor dialog box, you can specify the various settings that determine the appearance of materials in your rendered images, including applying pattern maps and bump maps.
Many settings are available that affect the appearance of materials. If you hover the pointer over these settings, in the Material Editor dialog box, a tool tip displays a description of the setting.
When you are defining materials for photorealism, a primary consideration is the efficiency setting for the material. This should never exceed 100%. Typical materials in the real world generally range in efficiency from 30% to 70%. When you turn on efficiency (Basic Mode) or lock it (Advanced Mode) it will remain at the selected value. As you adjust a material setting that affects the efficiency, then automatic adjustments will be made to the other settings to maintain the selected efficiency.
(Dark/Bright setting in Basic Mode) the intensity of the material's diffuse color — can range from Dark (no diffuse color) to Bright (100% diffuse color).
How the diffuse color is defined depends on the color setting. Click the color menu to see the following options:
Custom — lets you select a color, using a color picker dialog box, which is opened by clicking the color button.
Use element color — uses the color of the element(s) in the model to define the diffuse color.
| By mixing the diffuse color with a pattern map, the need for many different pattern maps is reduced. For example, both blue and pink marble materials could be created by mixing different base colors with a single marble pattern map. |
Translucency controls the amount of light that illuminates the side of the surface opposite the light source. That is, the percentage of incoming light that is transmitted through the material and scattered in all directions as it exits the material.
(Dull/Shiny control and Reflective toggle in Basic Mode) These three settings affect materials as follows:
Specular — sets the intensity of specular highlights, with values ranging from 0 (Dull) to 100 (Shiny).
Finish — controls the size of the highlight, with values ranging from 0 (Rough) to 100 (Smooth).
Reflect — controls how reflective the material is, with values ranging from 0 (None) to 100 (Full).
The Finish and Specular settings interact to produce specular highlights, or lighting “hot spots,” for a material.
A highly polished material, such as chrome that has high Specular and Finish values, produces concentrated and bright specular highlights.
A rough material, such as felt that has low values for Specular and Finish, has dull and more spread out specular highlights.
 | |
Left: Rough (low Specular and/or Finish), Center: Smooth (medium Specular and Finish), Right: Highly polished (high Specular and Finish). | |
(Opaque/Clear setting in Basic Mode) Sets a material's transparency and refractive index.
Transparency values range from 0 (opaque) to 1 (fully transparent).
 | |
Sphere with transmit set to 0 (left) and 0.6 (right). | |
Refract sets the index of refraction for the material. The index of refraction is the ratio of the speed of light in a solid material to the speed of light in air. The index defines how much light bends as it enters a material.
A value of 1.0 does not bend light at all.
A value greater than 1.0 causes the light to bend toward the surface normal of the object to which the material is applied
A value of less than 1.0 causes the light to bend away from the surface normal of the object.
Values for Refract range from 0.10 to 3.00, but refract values for commonly used materials are available from the drop-down menu, which is opened by clicking the arrow icon.
 | |
Sphere with Refract set to 1.000 (left) and 1.400 (right). | |
It is not uncommon to use surfaces, rather than solids, to model panes of glass in windows. This can cause rendering inaccuracies where refraction is concerned because the light is bent only as it enters the surface. In real-life glass has thickness and the light is bent in one direction as it enters the glass, and again (in the opposite direction) as it exits the glass. In these situations, you can use the Thickness setting to specify that the material has a thickness. Thickness is defined in master units.
This setting can be used to modify the refraction through a surface. For example, it is not uncommon to use surfaces, rather than solids, to model panes of glass in windows. This can cause rendering inaccuracies where refraction is concerned because the light is bent only as it enters the surface. In real-life glass has thickness and the light is bent in one direction as it enters the glass, and again (in the opposite direction) as it exits the glass. In these situations, you can use the Thickness setting to specify that the material has a thickness.
When applied to a solid, then a non-zero thickness would make the solid appear hollow.
Thickness is defined in master units.
The material's ambient reflectance — that is, the degree to which the overall ambient lighting is reflected by the surface — values can range from None (0) to Full (100).
A combination of the overall Ambient light setting, together with the material's ambient light, determines the surface's appearance in the rendered image.
| You can produce a material that appears to “glow” by keying in a value greater than 1 for Ambient. |
If on, the material can cast shadows. If off, the material will not cast shadows (the light will shine through it).
 | |
Left: Cast shadows on for all materials. Right: Cylinder's material has Cast Shadow turned off. | |
Used in conjunction with the Material Receives Light and Material Reflects Light settings in the Materials & Lighting section of the Radiosity dialog box and the Particles section of the Particle Tracing dialog box. Determine how the material receives and transmits radiosity illumination or particles. In either case:
If Material Receives Light is set to If global illumination on, this setting must be on for the material to receive radiosity illumination or particles. If set to If global illumination off, this setting must be off for the material to receive radiosity illumination or particles.
If Material Reflects Light is set to If global illumination on, this setting must be on for the material to transmit radiosity illumination or particles. If set to If global illumination off, this setting must be off for the material to transmit radiosity illumination or particles.
When you enter level/color assignements for materials via the Material Editor, or the Material Assignments dialog boxes, you can use wildcards in the assignment. Level/color assignments are specified as LevelRange : ColorRange. Currently, the only wildcard character supported is the asterisk “*”.
You can specify colors individually, separated by commas, or as a range separated with a hyphen. For colors, the wildcard character matches all colors. For colors, wildcard and non-wildcard characters cannot be combined, the wildcard takes precedence.
Examples:
wall : 1,3,6,20–30 matches colors 1,3,6, and colors 20 through 30 on level wall.
wall : * matches all colors on level wall.
wall is the equivalent of wall : * and matches all colors on level wall.
wall : 2* is the equivalent of wall : * and matches all colors on level wall.
You can specify levels individually, separated by commas, or as a range separated with a hyphen. For levels, the wildcard character “*” matches zero or more characters, as shown in the following examples:
1, 5, 7–13 : * matches all colors on levels numbered 1, 5, and 7 through 13.
w* matches levels wall, window and west entrance.
w*n* matches levels window and west entrance.
*oor matches door and floor.
*oor* matches door, floor and doorknobs.
Multiple wildcards can be entered on the same line, such as:
hvac*, *floor* :22 matches color 22 on all levels that begin with hvac and/or all levels that contain the word floor.
Where conflicting assignments occur, more qualified assignments override less qualified assignments. For example:
wa* : 22 has precedence over w* : 22. In other words, levels starting with wa would match the first assignment, and all other levels starting with w would match the second.
wall : 22 has precedence over w* : 22. In other words, levels named wall would match the first assignment, and all other levels starting with w would match the second.