Building a luminaire to be used in a Lightscape project.
The following is a review of some of the steps and involved in the process of building a luminaire model in the Lightscape Visualization Software. It is assumed that the reader has a general base of knowledge in terms of 3-D modeling and Lightscape. It is also important to point out that this is a summary of the major steps in modeling and, in theory, can be applied to any type of Lightscape project.
Creating the model to be imported into Lightscape
This is likely the most important step of the modeling process. It is important to provide a good solid foundation when beginning the model for any Lightscape project. Many problems can be traced back to the initial modeling approach, and can therefore be avoided by taking the appropriate precautions when developing a model.
One example is layer structure. The way a user sets up and applies objects in relation to the layers can save valuable time later in the development and application process. Objects and surfaces can be isolated by locating them on a single layer, so that all other layers can be turned off and an object can be isolated. The user can then select the object with ease, making assignments to materials, checking process controls, and other parameters quickly. The layer structure is therefore critical. Significant thought and care must be given to this topic when constructing a model.
There are certain restrictions that apply to models imported to Lightscape from other software packages. Lightscape cannot recognize objects that are modeled using certain commands. For example, objects modeled in AutoCAD using solid commands will not load and be recognized in Lightscape. The following list has been provided by Lightscape (Discreet Logic) and is a breakdown of some of the commands that can be used for AutoCAD and 3D Studio:
Solids
Polylines (closed) such as rectangles, circles and polygons
selected in the export dialog window. (Always use ACAD13 .DXF format because ACAD R14 LightWeight Plines are not supported by the DXF importer of Lightscape).
Polylines (or closed lines) with height
Polylines with thickness
Extruded closed polylines or splines
Spline with height
of the decurve command. (you can simply delete them in Lightscape).
3D Surfaces
Regions and Bodys
Lines and other non-3D elements
Lights
AutoCAD Cameras (Saved Views)
First import the *.3DS file in MAX (MAX will keep the cameras). Use the plugin to export to Lightscape from MAX.
Since the majority of surfaces modeled for Lightscape are one-sided, orientation of the surface is always critical. The beginning of the modeling process is the best time to pay close attention to surface orientation. The process for defining a surface orientation depends on the software used for modeling the object or luminaire. In AutoCAD, the right hand rule is used to determine the direction of the surface normal, or the orientation of the surface. Therefore, a surface whose points were drawn in counter-clockwise order on the flat, horizontal plane will have a normal that points in the positive vertical direction. The orientation of the surface will be up.
It is also important to remember that a luminaire must have a surface to which the photometric distribution can be applied. This photoplane can be a luminous opening, or in the case of most downlight distribution luminaires, a surface in the plane of the lamps. This can be accomplished by building a surface that is about the same size as the luminous opening. If the fixture emits light only up or only down, this surface should be positioned at the plane of the opening. If the luminaire emits light both upward and downward, this surface should be located at the center of the lamps, where it was located when the luminaire was photometered. The material properties of the surface or photoplane can be set to a transparent nature to insure the plane is not visible, or in the case of a lens, be assigned a luminous value for viewing purposes. Unfortunately, Lightscape does not permit a lens to be a different luminance when viewed from different directions.
Another important consideration in the construction of a luminaire model is the location of the origin. This is a good time to consider how the fixture may be placed in a space. The most logical origin location, or base point may be at the photometric center of a luminaire, however there are cases when another point may be more logical from a mounting standpoint. For a wall mounted luminaire, it is better to locate the luminaire origin on the surface that mounts to the wall.
Creating a Lightscape Model of a Luminaire
Importing
After a satisfactory model of a luminaire or object has been completed, it is ready to be imported into Lightscape. For AutoCAD users, a R13 version .dxf file will allow for direct importation into Lightscape. At this time two issues arise, units and the append/overwrite command. Both are simple but can prove costly if overlooked.
The units of the model are generally determined during the initial modeling phases. However, as with the rest of the modeling process, consistency must be maintained to ensure integrity. In the import window, it is important to select the units that were used to create the CAD model.
The append/overwrite option during importing is self-explanatory. "Append" adds to any current model already in Lightscape. The imported model will then be placed in relation to the origin of the model currently in use. "Overwrite" allows the imported object to delete and replace any objects currently in Lightscape.
Preparing Surfaces
The next step in building a luminaire model is preparing the surfaces of the model. These parameters will determine how the surface will appear when light rays strike the surface. To edit the properties or parameters of a surface, the user must first select the surface(s) to be edited. After selection, a single right-click of the mouse will bring up a menu of options. The following issues/definitions apply to these options:
Assign Material - By selecting this command a dialog box of current materials pops up and the user chooses the material to be applied to the selected surface(s). Consult the manual for material definitions of material properties and parameters. Photoplanes or surfaces used primarily for photometric web assignment need to have a transparency of 1.00 to be invisible in the model or project. Materials that you wish to glow should be assigned an appropriate luminance. This may be necessary to produce a luminaire that appears similar to the real product.
Orientation - As mentioned earlier, the best time to manipulate the direction a surface faces (its orientation) is during initial modeling. However, this is a good time to double-check surface orientation and correct any mistakes. By activating the orientation dialog box, the backside of all surfaces will automatically turn green. (For any surface whose front side is specified as green in color, it may be difficult to determine surface orientation. In these cases, changing the color, at least temporarily, is recommended) Keeping the orientation dialog box active allows the user to constantly view the orientation of surfaces. Turning on and off respective layers may be the best way to view and select specific surfaces, especially those in hard to see areas. Once again, the importance of a good layer structure is stressed.
Process Control - For a definition of the parameters associated with process control, consult the manual. Most of the surfaces of a luminaire should be non-occluding to prevent obstructions of any light emitted from the luminaire (all light which is considered in the photometric report must escape the luminaire to be properly considered). Under most circumstances, the process controls of a luminous surface may be set to non-occluding, non-receiving, and non-reflecting.
Smoothing - Any surfaces making up a curve should be selected together or as a group and "Make Smooth" should be checked under Smoothing. Lightscape will then treat the surface as a curved surface.
Assigning Textures - Sometimes the material properties of Lightscape just aren't enough to give a surface a "touch of realism". In many cases applying a texture can help to portray the material most accurately. By applying a texture, the material properties of a surface can be altered or even replaced by an image file. Consult the manual for specific details and instructions on how to apply a texture to a surface. For example: In the case of luminaires with perforated metal, the best solution found for modeling this effect is to apply a gradient to a luminous surface. The gradient gives the illusion that the different viewing angles of the surface allow varying amounts of light to penetrate. In actuality, the texture gradient is applied to the luminous surface and reduces the luminance that is visible, providing the proper illusion. The Lightscape manual also describes texture alignment and methods of alignment. Texture alignment boils down to one word - practice. Graphics programs, such as PhotoShop, can produce images that can be applied as a texture.
To apply a texture file, edit the properties of a particular material and simply add the texture file within the texture tab. Once a texture or image file has been applied to a material, the path of the file is usually added. This is fine if the project will stay on the same workstation and the image file is not moved. Such is not always the case. Here are a few rules for loading textures and relating this to the path of the file - Perhaps the easiest way to alleviate any problems is to delete the path and simply list the name of the file listed in the dialog box of the materials properties. In order to do this; however, the material must be in the same directory as the project or .lp file currently active. As long as the texture path includes just the file name, and the image file is located in the project directory, the program will load the texture successfully. The same also applies for a luminaire or block that is loaded into Lightscape. The path should include only the name of the image file and, in the case of loading a luminaire or block; the image file should be in the same folder as the library or .blk file. After the luminaire or block has been successfully loaded, the image file should then be moved or copied to the same folder as the project .lp file.
Creating a Block
Following the editing and specification of parameters for all surfaces, the luminaire model must first be converted into a block. Select all surfaces to be included in the luminaire, right-click and select "Create Block". The surfaces will then be made into a block and the block will be placed on the current layer. Layer association will be discussed in detail later in these instructions.
Defining as a Luminaire
After the luminaire model has been made into a block, the user can then right-click on the block name in the block table and select "Define as a Luminaire". The aforementioned block is now a luminaire and is ready to have the parameters set to the user's specifications. The luminaire properties/parameters dialog box automatically pops-up after the block has been defined as a luminaire. Consult the manual for definitions/explanations of the parameters of the dialog box. Following is a brief description of the parameters and some tips when modeling luminaires.
Assigning Photometrics - Whether the user browses for the desired .IES file or chooses a generic photometric distribution, the best way to assign a photometric web to a surface is to pick the surface to which the photometrics are applied. It is important that the orientation of the photometric web is correct - a downlight must be directed down, the plane that runs perpendicular to the lamps must be perpendicular to the lamps, etc.. Corrections can be made by rotating the photometric web about any of its three axes. The user must also decide on the type of distribution to be used for the luminaire in question. The manual best describes the difference between point, linear and area source distributions. Point sources will provide shadows will very sharp edges and may appear unnatural, but may be acceptable for small sources. Large fluorescent sources, in most cases, are most accurately modeled using area sources
It is important to note that the file path for an associated .IES file is critical when assigned to a luminaire. Most of the rules that apply to a texture file apply here, also. To eliminate most problems, delete the path of the .IES file and include just the file name. The file will now load properly if: the .IES file is in the same directory as the .BLK block file when loading a luminaire, or the .IES file is in the same subdirectory as the .LP project file when opening that particular model/project. The user can leave the path of the .IES file, but complications will arise if the .LP project file is moved to a new directory or computer. If files are being moved between computers, all texture files and .IES files must also be moved. These are not stored in the .IES file.
Layers - In finalizing the luminaire model, it is important to consider layer naming. A good recommendation is to place the luminaire and all surfaces associated with it on one layer. This is important since the luminaire is placed on the current layer when imported from a block file. Therefore, it is best to create a layer, name it appropriately (the name of the luminaire or object works best), and make this new layer the "current" layer. Select the luminaire, right-click and choose "Assign to Current Layer". Next, select all surfaces, right-click and choose "Assign to Current Layer". The luminaire is now on one layer, usually the model name, and all other layers can be deleted. When the luminaire is loaded from a block file (see next step), the model-named layer can be set to the current layer and single instances of the luminaire will be placed on the appropriate layer.
Saving as a .BLK File - Finally, the completed model is ready to be saved to a block file. Select, or single-click the luminaire in the Luminaires Table, right-click and select save. The program will prompt the user for a file name; this is the name of the block or .blk file that will contain the luminaire. This naming is up to the discretion of the user. A good example may be 9000.blk. This block file could then contain the 9000 series luminaires: 9021, 9031, 9041, etc. Any luminaire in the block with the same name as the luminaire being saved will be overwritten (the user will be prompted by Lightscape for confirmation). However, there is no way to delete a luminaire or object from a .blk block file. If a user wanted to change the name of a luminaire in a .BLK file, the luminaire could be loaded, the name of the luminaire change, then saved again, but the .BLK file would now have two identical luminaires with different names. To successfully accomplish this task, a new .BLK file must be created and all luminaires contained in the old block file must be saved to the new file.
Updating a Model - Updating an existing luminaire model can be complicated. One problem can be the assignment of all surfaces on one layer, making surface selection difficult. Once single layer association is complete, the valuable layer structure is gone. One solution is to have two models of the same luminaire. One model would be the completed model that gets saved into a .BLK file. The other model would be a saved version of the early stages, better suited for editing. After required editing, the final steps can be completed and the model saved in to the .BLK file. Experience is usually required to determine a good time to save the model for future changes.
Created by
Chad Watters
Pennsylvania State University
Department of Architectural Engineering