• Working Within Rhino
• Converting IGES Files
• Converting NURBS to Meshes
• Importing DXF File Into Photopia
• Working with Lamp Models

Working Within Rhino

Q: How do I perform basic tasks in Rhino such as zooming and picking?

A: If you are not familiar with Rhino, then the best way to learn its basic functionality is to follow one of its tutorials. If however, you are not interested in learning how to draw in Rhino but simply want to know enough to perform simple tasks, view drawings or convert IGES files, then the following will help.

Zooming:

1. The default view in Rhino contains 4 viewports, 3 of the primary view directions and a perspective view. If you want only a single viewport, then you can simply double click on the name of any of the viewports in its upper left hand corner. This will make that view full screen. If you want to go back to the original 4 viewports, then select View -> Viewport Layout -> 4 Viewports from the main menu.
2. Select View -> Zoom and any of the various options from the main menu in order to change the view in any of the viewports. All of the zooming options are also accessible with buttons on the main toolbar.
3. Select View -> Rotate to orbit around the model in the perspective view. The orbit function is where you hold down the left mouse button within the perspective view and as you move the mouse up and down or side to side on the screen, your position around the model rotates. Note that this function can also quickly be accessed by simply holding down your right mouse button from within the perspective view and then moving your mouse. You can add dynamic zooming by holding down the Ctrl button while holding down your right mouse button. The zoom gets larger or smaller as you move your mouse up and down on the screen, respectively.
4. When no command is active, right clicking your mouse repeats the last command, including the zoom commands.
5. Press the Esc key to cancel any command or dialog.

Layers:

1. You can change the layers that are displayed in your model by selecting Edit -> Layers -> Edit Layers. from the main menu. Alternatively, you can click on the red, white and blue striped wedge icon on the main toolbar.

Picking Entities:

1. You can pick any surface or curve in the drawing by clicking on one of its edges with the mouse. If the edge you select is a boundary shared by 2 surfaces, then Rhino will pop-up a dialog that allows you to toggle or scroll through the alternatives while it highlights them in the CAD view. Pick the surface you desire within this pop-up dialog.
2. You can select multiple curves or surfaces (entities) by dragging window around them. Note that Rhino supports 2 variations of this, select by "window" and select by "crossing." If you start your window to the left of your geometry and then drag it to the right, then you are in select by "window" mode. The CAD entities must be entirely within the window in order to be selected. If you start your window to the right of your geometry and then drag it to the left, then you are in "crossing" mode. All CAD entities entirely within and those which cross the boundary of this window will be selected. You will be reminded with mode you are in by the linetype of the window boundary. When in "window" mode the window boundary is drawn as a solid line. When in "crossing" mode, the boundary is drawn as a dashed line.

Modifying the Geometry:

1. If you wish to edit any of the model components, then you will find an entire suite of options under the Transform main menu item. Simply select the surface you wish to modify by clicking on one of its boundary lines, and then select the tool you wish to use such as Transform -> Move, and then follow the prompts on the command line.
2. Click on the Osnap box at the bottom of the screen to enable the snap modes such as Endpoint or Midpoint.
3. Click on the Ortho box at the bottom of the screen to restrict the movement of screen dragging actions to either up and down or side to side. Holding down the Shift button while dragging is a quick way to turn this feature on temporarily.

Converting IGES Files

Q: How do I convert my IGES file to a DXF file with Rhino?

A: Rhino will read IGES files of solid or surface based models and convert them to NURBS surface based models. The NURBS surfaces can then be easily converted to polygon meshed based models for use in Photopia, but before they are converted make sure that the parts in the model that use different material finishes are separated onto different layers. This is important since materials are assigned by CAD layer inside Photopia and sometimes all parts are put onto a single layer in IGES files. In this case, you must define a new layer for each part with a different surface finish and then move the parts to their appropriate layer. The steps for this are listed below:

1. Define all of the new layers you will require by selecting Edit -> Layers -> Edit Layers. from the main menu.
2. Click the New button with the Edit Layers dialog.
3. Type in a name that will help you identify the part. We suggest you use the Photopia layer naming convention to make importing the model into Photopia quicker. The Photopia convention specifies that layers begin with either "REFL-," "TRAN-," or "REFR-" to denote them being for reflectors, transmissive surfaces or refractors, respectively. See Chapter 4 in the User's Guide for more details.
4. Give the new layer a unique color by clicking on the color patch for that layer.
5. To help ease the process of assigning the NURBS surfaces to their appropriate layer, we recommend you turn Off each new layer.
6. Once all required layers have been defined, then click OK on the Edit Layers dialog.
7. To change the layer of a particular surface, click on one of the boundary lines of that surface. If the boundary you select is shared by 2 surfaces, then Rhino will pop-up a dialog that allows you to toggle or scroll through the alternatives while it highlights them in the CAD view. Pick the surface you desire within this pop-up dialog.
8. Once the proper surface has been selected, then choose Edit -> Layers -> Change Object Layer from the main menu and select the layer you want from the dialog displayed.
9. If you turned all of the newly created layers off, then the surfaces will be removed from the display as you assign them to their layers. To finish writing out the DXF file see the FAQ on converting NURBS based surface models to polygon meshed based models.

Converting NURBS to Meshes

Q: How do I convert my NURBS surface based model to a polygonal meshed based model for Photopia?

A: Rhino contains some very good facilities for creating meshed surface models (or polygon based surface models) from NURBS surfaces or solids. NURBS surfaces can be converted to meshes upon exporting them to DXF files or from within Rhino before the DXF export is started. The easiest method is to convert them at the time the DXF file is written. For greater flexibility on the detail of the mesh however, you can create the meshes for each NURBS surface from within Rhino prior to exporting the DXF file.

Converting NURBS Surfaces Upon Exporting to the DXF file:

1. To convert NURBS surfaces to meshes upon exporting to the DXF file, first select the entire model you wish to export. If the model includes Photopia lamps, then be sure to select from the Top view.
2. Select File -> Export Selected from the main menu.
3. Change the "Files of type" filter at the bottom of the dialog to "AutoCAD DXF," navigate to the proper folder, enter the filename and click the Save button.
4. Rhino will then display the AutoCAD Export Options dialog. You can accept the defaults.
5. From the Polygon Mesh Options dialog. Select the Detailed Controls. button. Skip to the Polygon Mesh Detailed Options section below.

Converting NURBS Surfaces Within the Drawing Editor:

1. To convert NURBS surfaces to a mesh based surface from within the Rhino drawing editor, click on the NURBS surface from which you wish to make a mesh.
2. From the Rhino main menu, select Tools -> Polygon Mesh -> From NURBS Object.
3. From the Polygon Mesh Options dialog. Select the Detailed Controls. button. Now skip to the Polygon Mesh Detailed Options section below. When finished with that section, return to the next step in this section.
4. Once the meshed surfaces are created, you can export them to a DXF file by following the steps listed in the first section. Note that we recommend you put all of the meshes onto unique layers to keep them separate from the original NURBS surfaces. When you create a mesh the NURBS surface still exists and unless you separate the 2 types of surfaces onto different layers they will simply be drawn on top of each other. It is important to separate the 2 when exporting to a DXF file since you need to select the particular surfaces you want to export to DXF. If you select both the mesh and the NURBS surface then you will get twice the number of surfaces you expected in Photopia.

Polygon Mesh Detailed Options:

1. Set the "Max Angle" and "Max Aspect Ratio" according to the detailed required for the particular part. We recommend a "Max Aspect Ratio" setting of 100. This is a setting which dictates how long and thin a triangle can become, the aspect ratio referring to the length of the triangle compared to its width. When set to lower levels, a mesh is created which unnecessarily subdivides long flat surfaces which in reality could be described accurately with a single rectangle.
2. The "Max Angle" setting refers to the maximum angular difference between the surface normals of adjacent surfaces. When using specular surfaces with relatively small light sources this setting should stay relatively small. We recommend a value of 10 degrees or less. If this value becomes too large, then you will see striations in your light pattern indicative of what the pattern would truly look like if the reflector were really faceted to that degree. If you want a quicker analysis knowing that the striations are not real, then you can set this value to 20 or more. Other general aspects in your light pattern will be accurate. It is common to make course models for early design iterations.
3. When the surfaces are black or have a material which scatters the light more, like white paint, hammertone, semi-specular, etc., then you can tolerate less accurate surface orientations and still get accurate analyses. The same holds true when larger light sources are used, such as those which have coated bulbs. In these cases you can increase the "Max Angle" to 20 or 30 degrees. Utilize the Preview button to see if the degree of accuracy introduces any obvious geometric problems.

Importing DXF File Into Photopia

Q: How do I import the DXF file created by Rhino into Photopia?

A: Follow the steps listed below:

1. Start by selected File -> Import Luminaire CAD File from the main menu in Photopia.
2. If you use the layer naming convention for Photopia, i.e. REFL-HOUSING, TRAN-LENS, then Photopia will automatically sense the layer types. If you do not use the Photopia layer naming convention, then you need to specify the layer type in the first import screen within Photopia. After all of the layer types have been specified, click Next at the bottom of the dialog.
3. The Activate Surfaces screen allows you to specify the surface orientations. Conveniently, the meshes that Rhino makes are such that all polygons of the mesh are oriented the same. Check to see that Photopia has rendered the reflective side of the surfaces in the same color as the layer in Rhino. Note that this is the color that is used on the part when viewed in wireframe mode. We recommend you orient the surfaces of only one layer at a time by clicking on the layer of interest in the list shown in the upper left hand part of the screen. Remember that you can gain full access to all CAD viewing controls by right clicking your mouse in the CAD view window. If the surfaces on a given layer are not rendered in the appropriate color on their reflective or "front" side, then select the "Reverse" Surface Orientation method, then click the "Select All Surfaces" button, then click the "Apply" button. This switches the orientation of all surfaces on the given layer. Once all surfaces have been properly oriented, click Next.
4. The last step is to add the lamp(s) to your model. Select the lamp you require from the list within Photopia and use the controls provided to add it and place and orient it. If you need more than one lamp, then add more lamps in the same manner. It is sometimes necessary to change the View Style of the CAD view to "wireframe" to see lamps within the luminaire. Click the Finish button when done.
5. You are then prompted to name and specify the location of the project. The default name and location match that of your CAD file. Note that the Photopia project is comprised of a series of files all sharing the same filename prefix.

Working with Lamp Models

Q: Can I place Photopia lamp models into my optical model within Rhino?

A: Yes, but you need to be careful about how you work with the lamp models in Rhino. The Photopia lamp models contain a text entity that is critical to the import process in Photopia. Rhino interprets this text as a dimension entity and only displays it in the Top view of the CAD drawing. Therefore whenever you "transform" a lamp (this includes functions such as scale, move, rotate, copy, and everything else under the Transform menu item in Rhino) you must select the lamp(s) to transform in the Top view so as to include the text entity. Selecting the lamp(s) in any other view will not select the text entity. When your model is complete and you want to export it to a DXF or DWG file you must also select the entire model from the Top view. See the other FAQ's for Rhino for details on how to import and place lamp models into your optical model.

Q: How do I import a lamp model into Rhino?

A: Follow the steps listed below:

1. To determine the filename of the lamp model you require, review the list of current lamps in the Lamps.xls spreadsheet located in the \LTI\Photopia\Lib folder. This spreadsheet is always updated whenever you receive library updates. The filename prefix for each lamp is listed in the first column. The lamps are listed by type and then wattage.
2. Once you have determined the filename of the lamp model you require, select File -> Import/Merge. from the main menu.
3. Change the "Files of type" filter at the bottom of the dialog to "AutoCAD DXF."
4. Navigate to the \LTI\Photopia\Lib folder to search for your lamp model.
5. Once found, click on it and then click the Open button.
6. All lamps are scaled to inches by default. If you are working in inches, then you are done. If you are working in a different unit, then you need to scale the lamp model. To do this, continue with the remaining steps.
7. We recommend you first turn off all layers in your drawing that are not related to the lamp model. All lamp layers begin with "LAMP-." Then select your lamp from the Top view and choose Transform -> Scale -> Scale 3-D from the main menu.
8. Enter 0,0,0 for the Origin Point.
9. Enter the proper value for the Scale Factor (25.4 for mm).
10. Select View -> Zoom -> Extents from the main menu to reset your view according to the new lamp scale.
11. Click your mouse on some blank part of the CAD view to de-select the lamp model.

Q: How do I move a lamp model in Rhino?

A: Follow the steps listed below:

1. Select the lamp model from the Top view so as to include the text entity included in the model.
2. All lamps import centered around 0,0,0. This point generally defines the center of the luminous part of the lamp, thus the arc in HID's or the center of the length of the tubes in a CFL.
3. Select Transform -> Move from the main menu.
4. Enter 0,0,0 as the point to move from.
5. Enter the 3D coordinate of the point to which you wish to move the lamp.
6. Click your mouse on some blank part of the CAD view to de-select the lamp model.

Q: How do I change the orientation of the lamp model in Rhino, for example, from base-up to base-down?

A: Follow the steps listed below:

1. Select the lamp model from the Top view so as to include the text entity included in the model.
2. Select Transform -> Rotate from the main menu.
3. Enter the lamp location as the Center of Rotation. If the lamp has not been moved after importing it, then enter 0,0,0.
4. Enter the desired rotation angle noting that the effect on the lamp changes depending on which view is "active." The active view is the one in which your mouse is located and whose label is highlighted in blue. If you are changing a lamp from base-up to base-down, put your mouse in the Front view (assuming you are using Rhino's standard 4 view port screen configuration) and then enter a value of 180 degrees.
5. Click your mouse on some blank part of the CAD view to de-select the lamp model.

Q: How do I create an array of lamp models in Rhino?

A: Follow the steps listed below:

1. Select the lamp model from the Top view so as to include the text entity included in the model.
2. Select Transform -> Array and then either Rectangular or Polar from the main menu.
3. For a rectangular array, enter the number of objects for the X, Y and Z directions and then the spacing between objects for each of these directions. If you do not wish to array in a given direction, then leave the number of items at 1. For example, if you want a 4x3 array of lamps in the X-Y plane, then enter 4 in the X direction, 3 in the Y direction and 1 in the Z direction.
4. For a polar array, enter the center point of the array. Note that the view your mouse is within when the center point is defined sets the plane of the polar array. Thus, if you have your mouse in the Top view, then the polar array will be in the X-Y plane.
5. Next enter the number of elements in the array.
6. Next enter the angle to fill. This is the angle measured from the center point, between the first and last elements.
7. Click your mouse on some blank part of the CAD view to de-select the lamp model.