This section is where you can choose materials from the libraries, modify them as necessary, create new libaries and materials, and render them to see how they may appear in a Radiance model.
The scroll window displays all the current libraries available to choose materials from. Select a libary and it’s material contents will be displayed in the Materials window to the right. The New Library button will bring up a window to enter the New Library Name. This will create an empty library with the given name. The Import Library button will bring up an import window asking for the name of a Radiance library to import. This can be any text file that has valid (and SPOT supported) Radiance material definitions. See below for the types of materials SPOT currently supports. The Delete Library button will delete the currently selected Library.
The scroll window displays all the available materials in the currently selected library. Select a material and the material details will show up in the Material Editor section below. The New Material button clears the Material Editor fields so the user can input custom material information and save into a library. The Save Material button will then save a new, or modified, material definition with the current material name (note that no spaces can exist in the name) back to the current library. This can be used for new materials or for modifying, or ‘cloning’, existing materials. For this, just pull up an existing material, modify as necessary and either hit save with the same name to Modify the material or change the name and save to create a clone of the material. The Delete Material button will delete the currently selected material.
These fields allow you to access the details of any material or pattern. The Render button will run a quick Radiance simulation and display an image of the currently selected material on a sphere. This best shows what the material may look like in a Radiance model under the variable lighting and shadow that will exist. The Import to Project button will import the currently selected material to the project list. Only materials that have been imported to the project can then be applied to a surface in your SPOT model. The different material and pattern types are available and their control parameters are discussed below:
Plastic – This material type is most common and can model most opaque surfaces that do not have unique specularity characteristics like those of metals or assymetric surfaces. It is a material with uncolored highlights. The following 5 parameters control the appearance:
- Red refl, Green refl, Blue refl – These fields set the RGB reflectance of the material.
- Specularity – This field sets the fraction of the reflectance that is specular in nature. Most materials have a specularity fraction less than 0.1.
- Roughness – This field sets the roughness value of the surface. A value of 0 is a perfectly smooth surface. A value of 0.2 is a fairly rough surface and roughness values greater than 0.2 are uncommon.
Metal – This material type is similar to plastic except the specular highlights are modified by the material color. The following 5 parameters control the appearance:
- Red refl, Green refl, Blue refl – These fields set the RGB reflectance of the metal. These will affect both the diffuse and specular reflectance.
- Specularity – This field sets the fraction of the reflectance that is specular in nature. Most metals have a specularity fraction greater than 0.9.
- Roughness – This field sets the roughness value of the surface. Values greater than 0.2 are uncommon.
Glass – This material type as the name suggests is for modeling thin glass surfaces with an index of refraction of 1.52 (n = 1.52). The following 3 parameters control the appearance.
- Red trans, Green trans, Blue trans – These fields set the RGB transmissivity of the glass. Transmissivity is the amount of light not absorbed in one traversal of the material. Transmittance, the value usually measured, is the total light transmitted through a pane including reflections.
- To compute transmissivity (tn) from transmittance (Tn) use: tn=(sqrt(0.8402528435+.0072522239xTnxTn)-.9166530661/.0036261119/Tn
Trans – This material type is for modeling translucent (diffusing) transmissive materials. These materials can have a reflective and absorbtive component as well. The total Transmittance (specular and diffuse), Reflectance (specular and diffuse) and Absorbtance must be equal to 1 to ensure conservation of energy. The following 9 parameters control the appearance:
- Diffuse Refl – This field defines the diffuse reflectance of the material.
- Specular Refl – This field defines the specular reflectance of the material.
- Absorbtance – This field defines the absorbtance of the material.
- Diffuse Trans – This field defines the diffuse transmittance of the material.
- Specular Trans – This field defines the specular transmittance of the material.
- Roughness – This field defines the surface roughness. A value of 0 is a smooth surface and is necessary if a specular transmittance (view) component is desired such as the case with bug screens or fabric meshes. A value of 0.2 represents a fairly rough surface.
- Red Ratio, Green Ratio, Blue Ratio – These fields define the relative color of the material. These can be entered as any value – the relative relationship is what matters.
Mirror – This material type is for modeling perfectly specular mirrors that will be considered in the direct calculation in Radiance as virtual secondary sources. The following 3 parameters control the appearance:
- Red refl, Green refl, Blue refl – These fields set the RGB 100% specular reflectance of the material.
BSDF – This material type is for modeling surfaces that scatter the transmitted and/or reflected light and can be described with a Bi-Directional Scatter Distribution Function (BSDF) file. SPOT Pro uses the standard .xml format defined by Lawrence Berkley National Labs and used in the Windows 7.0 and Radiance software. The following 5 parameters control the appearance:
- Thickness – This field defines the overall thickness of the geometry being represented by the BSDF file. If the BSDF file represents a planar system this should be left at 0 which means the BSDF file will be applied to a plane and will will interact with both the direct and ambient calculations in Radiance. If it is a “System BSDF” file and represents a larger optical system than the thickness should represent the distance between an output plane (where daylight enters the space) and an input plane (where daylight is collected) of the system. The system will be modeled with the given depth in Radiance. Care should be taken to ensure the roof depth is as desired, so that the system is not modeled recessed into the roof or ceiling.
- XML File – This field defines the name of the XML file to use. The file will need to be provided separately (SPOT does not generate an XML file currently) and will need to be manually copied to the XML directory located at C:\SPOT\materials\xml for the material to work correctly.
- Orientation X, Orientation Y, Orientation Z – These fields define the orientation of the XML file. This is the orientation of the +Y vector when using genBSDF to create the BSDF file. The orientation vector is typically up (0,0,1) for side daylighting products and usually north (0,1,0) for top daylighting products.
- Sys.Trans – This field is only used if the BSDF file has a thickness. In this case, the BSDF file does not directly affect the direct calculations and so a proxy geometry is created in between the systems’ input and output planes that will have this approximate effective transmittance when dealing with the direct calculation. This should be approximately the systems hemispherical transmittance.
Corrugate – This is a pattern type for modeling an undulating surface like a corrugated metal deck. The following parameters control the appearance:
- Direction [X, Y, Z] – This sets the direction of the corrugation. A setting of X will make all the ridges run perpendicular to the X axis and so forth.
- Magnitude [0 – 1] – This sets the magnitude of the corrugation. A value of 0 would be a perfectly smooth surface and a value of 1 would make the height of the corrugations match the spacing of the corrugations.
- Frequency [>0] – This sets the frequency of the corrugation. The value sets the number of times the material oscillates in 1 meter.
Perforate – This is a pattern type for modeling perforated surfaces like punched metals or glass pv products. The following 6 parameters control the appearance:
- Openness [0-1] – This sets the openness (or coverage in the case of an opaque hole material) of the overall perforation pattern. A value of 0 will make no holes/dots, (would be all base material, and a value of 1 would be all hole/dot material.
- Scale [>0] – This sets the overall scale of the perforation relative to 1 meter square. For example, a value of 0.1 would make a pattern of 10 perforated holes/dots per 1 meter of material.
- Shape [Round,Square] – This sets the shape of the perforated holes/dots to be either circular or square. The perforation pattern is not offset from row to row or column to column and so makes a uniform pattern of the holes/dots.
- Base Material – This sets the base material to use. This is the material that will used when the perforation pattern is not making holes or dots This material can be void or a glass if the perforation is a pattern of dots or an opaque material such as a frit.
- Hole/Dot Material – This sets the hole/dot material to use. This material will be used when the perforation pattern is indicating a hole or dot.
- Surface [X, Y, Z] – This sets the orientation of the holes. Choose X if you want the holes/dots to be punched in the X direction and so forth.
Brick – This is a pattern type for modeling brick or tile patterns. The following 8 parameters control the appearance:
- Grout Width [>0] – This defines the width of grout between each brick in meters. A value of 0.01 gives a 1cm grout.
- Brick Height [>0] – This defines the height of each brick in meters.
- Brick Width [>0] – This defines the width of each brick in meters.
- Offset [>0] – This defines the offset between two adjacent rows of bricks. A value of 0 would align the bricks creating a uniform grid or tile pattern. A value equal to 1/2 of the brick width would offset each row of bricks by 1/2 of the brick width creating a typical brick pattern.
- Brick bright [1 +/-] – This defines the relative brightness of the bright pattern. As this pattern is applied to a surface that will also have a material applied to it, this will adjust that materials reflectance up or down by this multplier to create the brick pattern.
- Grout bright [1 +/-] – This defines the relative brightness of the grout. As this pattern is applied to a surface that will also have a material applied to it, this will adjust that materials reflectance up or down by this multplier to create the grout lines.
- Surface [Vert, Horiz] – This defines whether the brick pattern will be on a horizontal surface or a vertical surface. Tile floor patterns would typically be applied to a horizontal surface where as brick patterns may typically be applied to a vertical surface.
- Scale [>0] – This defines the overall scale of the brick pattern. A value of 1 means the base unit is 1 meter and the width and height inputs above are in units of a meter. Any other value adjusts these other parameters relatively and can be used to create larger or smaller patterns without adjust each individual parameter.