Using the CAD to ASAP TranslatorImporting CAD-exported files to ASAP
This technical publication describes how to use the CAD to ASAP Translator to import GTX, IGES, or STEP files in the Advanced Systems Analysis Program (ASAP®) from Breault Research Organization (BRO). Geometry can be created outside the working environment, and imported to ASAP. Computer-Aided Design (CAD) software creates and exports this geometry as a standard file.
ASAP supports CAD output file translation of these file types via its translator: GTX (*.gtx), IGES (*.igs), and STEP Part 42 (*.step, *.stp). The add-on CATIA Module for ASAP is required for translation of CATIA V5 (*.catpart, *.catproduct) files. See the ASAP Help topic, “Supported Files for Translation”.
TIP Although this technical publication specifically focuses on translating IGES files, it can be applied to importing the other supported CAD formats unless otherwise noted.
When ASAP users need to import geometry created by other software to the ASAP working environment, this can be performed in two steps:
1 Export the geometry from CAD to the Initial Graphics Exchange Specification (IGES), which
allows for standardized geometry exchange between various CAD software programs.
2 Open the IGES file in ASAP to start the IGES (or CAD) to ASAP Translator, which converts the file
format into ASAP file format (*.inr).
Topics discussed in the remainder of this technical publication include:
• “Export IGES File from CAD Software” on page 2
• “Example: Translating iges to INR” on page 3
• “Observe Modifications” on page 11
• “Translate IGES to INR” on page 12
• “Run INR and Visually Verify the Translation” on page 13
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EXPORT IGES FILE FROM CAD SOFTWAREIn this document, demonstration emphasis is placed on SolidWorks® CAD software. However, most CAD software packages can export IGES files.
ASAP objects can be placed in two categories: surface-based and edge-based objects. Surface-based objects have the advantage of rays that can trace quickly through them, because they are defined by equations. Most native-language objects in ASAP are surface based. Edge-base objects are defined by connected points, lines, curves, and edges, which increase ray-trace time because they are complex and not defined by equations. Most CAD-exported objects are edge based.
Descr ib ing sur faces• IGES offers some flexibility as to how surfaces are described. Most CAD systems give users
the ability to specify the process, via a user interface, during the export and after saving a file as IGES. B-Spline surfaces in a CAD system that are trimmed by other surfaces or edges can be described in IGES as either Bounded (143) or Trimmed (144). If an export option is available in the CAD software, use the Trimmed (141 or 144) option.
• If the CAD system is a solid modeler, set it to output the solids as separate surfaces, if possible.
Compar ison test ing for sur face a l terat ion ( IGES only)Perform the following test if there is any doubt about the integrity of the translation process:
• Translate the surface into ASAP.
• Export the surface from ASAP to a new IGES file by clicking System, Export to CAD. This step applies only to exporting IGES files. ASAP does not support exporting other file formats.
The exported IGES file is a representation of the ASAP INR geometry that was translated from the original IGES CAD file. The newly created IGES file can be read into the CAD system, and the new surface can be compared to the original surface.
NOTE A perfect “round trip” may not occur if the default options for ASAP and/or CAD are considerably altered.
Surface repai rIf the CAD software (other than SolidWorks) yields an IGES file that is incompatible with ASAP, use SolidWorks to facilitate compatibility.
• Open the CAD file in SolidWorks.
• Use the Repair Surface tool in SolidWorks to fix gaps and other irregularities. Follow the wizard prompts.
• The geometry can be exported from SolidWorks to a supported file that is suitable for the CAD to ASAP Translator. Click File, Save as [file type].
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F i les that conta in objects wi th l ike object propert iesAlthough not required, you may find it convenient to group surfaces with like object properties (such as coatings, media, color) into different files. For example, a lamp assembly may have all reflective components placed in a file named reflect.igs, while all lens components are placed in lens.igs. However, best practices for layering and CAD should allow for the translation of just one file.
EXAMPLE: TRANSLATING IGES TO INR The CAD to ASAP Translator converts supported files into ASAP INR files, and also allows the assignment of object properties and object names. The act of opening a CAD file in ASAP begins the translation, which flows sequentially to completion with some minor user inputs. The following example uses an IGES file, but the steps are similar for other supported CAD file formats.
Opening IGES f i les wi th ASAP• Click File, Open (type IGES or All types) in ASAP.
• Click the desired IGES file. The IGES Setup Parameters box is displayed.
IGES Setup Parameters• Default values for setup, as shown in Figure 1, are typically sufficient for most geometry. Click
Help for more information on any of the setup parameters. Details may change in an ASAP release, and ASAP Help is updated accordingly. A brief overview is given here:
Independent curves: Import curves that do not form surfaces.
Create Specific Surface-Based Objects: Detect edge-based objects and convert to surface-based equivalents.
Parametric Space Trimming: Use parametric trimming instead of model space trimming.
Use Filename as Root Object: Use an object naming scheme that branches objects from the file-name.
Try Other Approximation to Spline Surfaces: Select so that the other approximation (even though it uses more CURVES) is closer to the original NURBS.
Use Accelerated Open GL: Select to use an optimized pixel format.
Use Model Accuracy: Import using the degree and product specified for the geometry in the file. No approximation of the underlying geometry is performed where possible to improve import ac-curacy and shape identity of the geometry; however, ray tracing may slow due to a more complex geometry.
Locate Duplicate Geometry: Reports detection of duplicate-surface geometry. Occasionally, CAD-created geometry is overlaid, and unnecessary duplicate geometry can cause ASAP wrong-side errors.
Geometry Conditioner: Enables the Geometry Conditioner (click Help for more information).
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Figure 1 IGES Setup Parameters - default settings
• Click OK. The IGES to ASAP Translator is displayed.
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IGES to ASAP TranslatorThe IGES to ASAP Translator lists the name, coating(s), and media for each object in column format. Object names may be modified here. Branched objects retain object name prefixes. See the topic, “Translator Window (GTX, IGES, or STEP Files)” in ASAP Help for information on this dialog box. See Figure 2.
Figure 2 IGES to ASAP Translator window
NOTE The low-resolution wireframe view of the geometry that is displayed on the lower portion of the dialog box is only for viewing. This view cannot be used to adjust the orientation of the file.
If you want to translate an IGES file immediately to an INR file without assigning object properties, press Enter. The INTERFACE assignment can be done post-translation in ASAP via standard methods. However, for convenience, you can modify object properties via the IGES to ASAP Translator, as described in subsequent sections.
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Edit , Modi fy• Click the root object name on the IGES to ASAP Translator, as shown previously in Figure 2,
to apply changes to all objects that branch from it.
• Click Edit, Modify to open the Modify Object dialog box. See Figure 3.
Figure 3 Modify Object dialog box
• Select an object branch on the menu under Name / Alias. Details associated with the Modify Object dialog box are explained next.
C o a t i n g
Object coatings are listed on the Coating menu (BARE, ABSORB, REFLECT, or TRANSMIT). A new coating may be created if it is not listed on the menu.
Create a new coating
• Click New Coating on the Modify Object dialog box to open the Coating dialog box, as shown in Figure 4.
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Figure 4 Coating dialog box, associated with Modify Object
• Type the coating name, and reflection and transmission values between zero and unity.
• Click OK.
Your new coating is now available on the Coating list on the Modify Object dialog box.
M e d i a
The Modify Object dialog box, under Properties, lists object media for Media 1 and Media 2. Two media should be assigned per object. Existing media names are listed on the menu, such as AIR or DEFAULT. New media may be created if they are not listed for either Media 1 or Media 2.
Create new media
• Click New Media on the Modify Object dialog box to open the Media dialog box. See Figure 5.
Figure 5 Media dialog box, associated with Modify Object
• Type the medium name and refractive index for the primary wavelength. Polychromatic and absorptive (complex) media can be defined later in ASAP.
• Click OK. Your new medium is now available for object modification on the menus for Media 1 or Media 2.
C o l o r
Color is assigned individually as DEFAULT for objects in a repetitive color sequence. To change the color for objects or branched objects, use the Color menu on the Modify Objects dialog box. Refer to Figure 3.
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F a c e t s
ASAP globally facets all objects automatically in the file. However, individual objects or their branched objects can be manually specified on the Modify Objects dialog box, under Intra-Edge and Inter-Edge, using the arrows. Refer to Figure 3.
S c a t t e r H a l f A n g l e
The option, Scatter Half Angle (degrees), assigns a Gaussian-shaped scatter pattern to the object. The value that is entered for the angle is the half-width at half-maximum angle in degrees of the pattern.
F r e s n e l A v e r a g e
Performs averaging with Fresnel S and P states.
S p l i t 1 A l l
Assigns objects a level 1 ray split characteristic at the interface.
A d v a n c e d
Click Advanced to display the section, Advanced Object Definition on the lower part of the Modify Object dialog box.
Recursive
Applies properties to all child objects so that they receive the same attributes as their parent ob-ject(s).Clear
Deletes attributes for the parent object, including all child objects. If some child objects are select-ed, only those child objects are cleared.
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The Modify Object dialog box now is complete. See Figure 6.
Figure 6 Completed example of the Modify Object dialog box, showing coating
• Click OK to close the Modify Object dialog box and return to the IGES to ASAP Translator.
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Edit , Mater ia lsClick Edit, Materials on the IGES to ASAP Translator to display the Materials dialog box, which is a method for reviewing, deleting, or modifying coatings or media. See Figure 7.
Figure 7 Materials dialog box
• Make any desired changes on the Materials dialog box, and click OK.
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Observe Modi f icat ionsModifications are displayed in the columns of the IGES to ASAP Translator. See Figure 8.
Figure 8 Expanded view of the modified IGES to ASAP Translator
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Translate IGES to INR• Press Enter or click File, Finish to complete the final translation process to an INR file. See
Figure 9.
Figure 9 Example of a translated IGES file into an ASAP INR file
• Note media and coatings in the INR file. Also note object modifiers below the object. These labels reflect the completed settings of the Modify Object dialog box as displayed in Figure 6.
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Run INR and Visual ly Ver i fy the Translat ion• Run the INR file with the VUFACETS command. See Figure 10.
Figure 10 Results of VUFACETS command with FACETS 3.5 global default setting
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In this scenario, local Faceting was set on the EQUIV LENS objects. Isolating these objects in the Viewer shows the higher level Faceting. See Figure 11.
Figure 11 Faceting of EQUIV LENS, set at 5 7 in the Modify Object dialog box as displayed in Figure 6.
This completes the example for the IGES to ASAP Translator, which can be used for other CAD file translations.
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Appendix: Best Practices 15
Appendix: Best PracticesThis appendix describes best practices for CAD export of GTX, IGES, and STEP (Part 42) files for use in ASAP. CAD output files include GTX (*.GTX), IGES (*.igs), and STEP (*.stp, *.step) files.
1 GTX: ASAP GTX files are preferred for translation to ASAP INR format. If available in the CAD
software, select Save As ASAP (*.gtx). For SolidWorks, an add-in is required for GTX export.
To initially activate GTX export, select Tools, Add-ins and click SolidWorksASAPExport on the
dialog box. ASAP must be installed on the same computer to view this option.
2 IGES: Exporting IGES format
a In SolidWorks, click File, Save As, click IGES, Options, and click IGES, Options, IGES
solid/surface entities (type 144).
b If you are saving from another CAD program, try to select options with similar surface export
parameters.
3 STEP: Exporting STEP format
a In SolidWorks, click File, Save As, STEP AP214.
b If you are saving from another CAD program, try to select options with similar surface export
parameters.
4 Do not export construction geometry, such as user-created axes, non-surface-related points,
lines, or curves that do not make up surfaces.
5 Hide or delete redundant surfaces. Zoom to extents to verify entities do not exist outside your
regular viewing window.
6 With SolidWorks, construct part trees and branches with similar optical properties. Use layering
when possible. Layer items with similar optical properties.
7 Verify that the system’s starting point or vertex is on construction axes that are convenient to
ASAP. Set construction axes in CAD software to avoid further rotation and/or shift manipulation
with ASAP.
8 Convert meshes to polysurfaces. Merge surfaces when possible to reduce object quantities.
9 Verify that no open surfaces exist. Perform a shaded view of your system before export. Inspect
for and resolve any obvious surface anomalies.
10 SolidWorks has a file repair filter. If a different CAD software is used for the system construction
and export file anomalies exist, import the exported file to SolidWorks and re-export it as ASAP
GTX, IGES, or STEP.
A p p e n d i x : B e s t P r a c t i c e s
11 Other issues affecting IGES import may be corrected by deselecting Parametric Space
Trimming, or increasing accuracy settings on the CAD export options. The preferred method is
to select Parametric Trim Curves.
12 NURBS with weights of zero (0) may cause problems when exported to IGES. Setting the weight
to a small fraction, rather than to 0, may help.
13 When exporting IGES from CATIA, an option exists for exporting curves and surfaces, either
standard or utilizing BSplines. Select the BSpline option. The precise location for finding this
option is: Tools, Options, General, Compatibility. Select the IGES tab and select Curve and
surface type.
NOTE If you are using CATIA as your primary CAD program, you can significantly increase accuracy with the CATIA Module for ASAP. The CATIA Module allows ASAP CAD users to open native CATIA V5 files from within ASAP.
Table 1 Supported IGES entity types in ASAP INR files
Type Name
100 Circular Arc
102 Composite Curve
104 Conic Arc
106 Copious Data
106 Simple Closed Planar Curve, Form 63
108 Plane (bounded)
110 Line
112 Parametric Spline Curve
114 Parametric Spline Surface
116 Point
118 Ruled Surface
120 Surface of Revolution
122 Tabulated Cylinder
123 Direction
124 Transformation Matrix
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Appendix: Best Practices 17
126 Rational B-Spline Curve
128 Rational B-Spline Surface
132 Connect Point
140 Offset Surface
141 Boundary
142 Curve and Parametric Surface
143 Bounded Surface
144 Trimmed Parametric Surface
190 Plane Surface
192 Right Circular Cylinder
194 Right Circular Cone
196 Spherical Surface
198 Toroidal Surface
308 Subfigure Definition
314 Color Definition Entity
402 Group Associativity (Form )
406 Level Function, Form 3
406 Name Property, Form 15
408 Subfigure Singular Instance
412 Rectangular Array Subfigure Instance Entity
Table 1 Supported IGES entity types in ASAP INR files
