The following information may be helpful to those using Inventor to create 3D models for Photopia:

Q: How can I import my Inventor CAD model into Photopia 2.0?

A: There are 2 options for importing models from Inventor into Photopia. The first option uses STL files that can be saved directly from Inventor and imported into Photopia. The second option uses SAT files and requires the use of AutoCAD to convert the files to DWG files. If you have AutoCAD, then the second option is generally preferred.

• 1. You can export stereo lithography files (STL) from Inventor part files. Inventor does not provide STL export from the assembly drawings. Therefore, you need to open each part file and export it to a uniquely named STL file. You can then import the entire range of STL files into Photopia in a single step using the Luminaire Import Wizard.
  • See the STL File Considerations section of Chapter 4 of the User’s Guide for additional information on working with STL files.
  • See the Luminaire Import Wizard section of Chapter 4 of the User’s Guide for a complete description of the import process.
  • When STL files are exported from individual part files, you need to aware of the individual part transformations (location and orientation) with respect to each other. You also need to be aware of where the light center is located within the luminaire. The individual STL files will have coordinates with respect to the local coordinate system used to create the part. You will need to know how each part coordinate system is related to the other parts so that the parts can be properly assembled within Photopia. Using a common origin and orientation for each part will make importing the model into Photopia much easier since the need for transforming the parts within Photopia will be avoided. When a common origin and orientation are not used, then you can find part rotation and translation data in the part “occurrence” data under the part properties in the assembly drawing.
• 2. If you have AutoCAD, then you can convert the Inventor model to a 3D DWG file by first exporting the assembly drawing from Inventor to an ACIS (SAT) file and then following these steps:
  • Import the SAT file into AutoCAD by choosing Insert / ACIS File from the menu.
  • Set the mesh resolution with the FACETRES system variable. The default value of 0.5 is very low and results in a course polygon mesh approximating the shape of your model. We recommend you set the value to a higher level to create a more accurate part shape. If you are using Photopia 1.5, then a value between 5 and 8 is recommended. If you are using Photopia 2.0, then use the maximum setting of 10.
  • Export the solids to a 3D Studio files using the 3DSOUT command or by selecting File / Export from main menu and setting 3D Studio as the file type. If you have AutoCAD 2007 or later, please follow these directions to enable the 3DSOUT commend. Keep the default settings on the 3D Studio File Export Options screen. Note: If the mesh contains too many vertices, then AutoCAD will not export the part. The 3DSOUT command will give an error message if this occurs. If you encounter this problem, then try one of the following options:

    a. Reduce the FACETRES variable to a lower value and try again. If the 3DSOUT command continues to fail or if the facet resolution is not acceptable at the level AutoCAD will support, then try the next option.

    b. Use the EXPLODE command on the solid to convert it to a set of regions and/or bodies. Then create several new layers and put a portion of the regions and bodies onto each of the new layers. Now try and export the set of regions and bodies from each layer individually using the 3DSOUT command. If it still fails, then reduce the amount of geometry on each layer until it succeeds.

  • Import the 3D Studio file into a new AutoCAD drawing using the 3DSIN command or by selecting Insert / 3D Studio from the main menu. Click the Add All button in the Available Objects section of the Import 3D Studio File Options screen and keep the rest of the settings at their default values.
  • Save the meshed parts to a .DWG file. The .DWG file can be imported into Photopia.
  • Using this method to convert an Inventor drawing into a meshed model for use in Photopia allows the relationship between the various parts in the assembly to be retained.
  • See Chapter 4 of the User’s Guide for additional information on importing DWG files using the Luminaire Import Wizard.
• Whether you use STL files or a DWG file for your Inventor model, you will need to specify the Photopia lamp model location(s) within your luminaire. This can be done either during the Luminaire Import Wizard or after the luminaire has been completely imported, using Photopia’s internal CAD system.
  • The Photopia lamps are all constructed so that their light center is at 0,0,0. Therefore, if you can setup your luminaire assembly so that 0,0,0 is at the lamp center then it will be very easy to locate the Photopia lamp model within your luminaire. If the luminaire uses multiple lamps, then putting 0,0,0 at the center of all lamp location is convenient.
  • If it is not convenient to locate 0,0,0 within your model at the lamp center, then we recommend you construct a small cone in your assembly so that the tip of the cone points to the lamp center(s). This way, when the lamp is imported into Photopia and its location is requested, you can use the Osnap to an Endpoint to pick the end of the cone. You can turn off the cone layer within Photopia once the lamps are placed so they will not affect the optical analysis.