Advanced concepts and clues for development

Until now, we have seen everything for creating great models and obtaining excellent rendered images. In this appendix we see how to create simple animations, how to prepare a model and export it, and also suggest how to progress in 3D.

Animation

AutoCAD has limited capabilities for creating animations, which are described here. With the next command, we may associate a camera and its target to points or paths and animate it.

The ANIPATH command

The ANIPATH command (no alias) allows simulating a walkthrough or a see-around. This command displays the Motion Path Animation dialog box where a camera can be associated to a point or a path, and the camera target can also be associated to a point or a path. Paths are linear objects, which were previously created.

This dialog box has the following areas and options, as displayed in the next screenshot:

• Camera: This command automatically creates a camera that can be associated to a point (fixed camera) or a path (moving camera). The button hides the box temporarily, allowing you to mark a point or to select a linear object. After selection, a box to introduce a name is displayed.

• Target: This camera target can also be a point or it follows a path, which is eventually the same as that of the camera's. The button allows you to select the path or a point.

• Animation Settings: Frame rate (FPS) defines how many frames per second is the animation velocity. Number of frames controls how many frames will have the animation. Duration (seconds) controls the animation duration. Modifying duration and the number of frames adjust accordingly. The Visual style list controls which visual style or render preset will be used in the animation. Format allows you to choose the animation type between AVI, MOV, MPG, or WMV. Resolution allows you to choose the resolution, the maximum being 1024 x 768. With Corner deceleration checked, the animation slows down on the corners. Reverse reverses the animation.

• When previewing show camera preview: With this option unchecked, the camera or target animates on the viewport, but no preview window having the camera view is displayed when pressing the Preview button.

• Preview...: This button displays an animation preview.

  

• OK: This button creates the animation. A File dialog box is displayed and then the animation process starts. Depending on model complexity, materials, lighting, animation resolution, and number of frames, the calculation may take a huge amount of time. Basically, the time taken is similar to the time of a single render with the same resolution times the number of frames.

  

Note

The ANIPATH command has several severe limitations: it is not possible to associate an existing camera to create the animation, it is not possible to control the camera's parameters, such as lens length or field of view, and it is not possible to control output quality, such as selecting an animation codec.

Connecting to other programs

Often we need to import or export our model to other programs, such as 3ds Max or Revit. As we are dealing with different types of files, some care must be taken.

Typical 3D import and export formats

It is quite simple to connect to AutoCAD. Besides the AutoCAD DWG file type that most CAD systems can export or import, the program accepts several 3D file types:

• SAT: These are the ACIS solid modeling files

• FBX: These are the 3D standard files that allow sharing 3D models between Autodesk software, such as Revit

• DGN: These are the Microstation files

• IGES and IGS: These are the standard neutral files

• STL: These files are only for exporting stereo lithography files, which are used for prototyping machines

Additionally, AutoCAD can import the following file types:

• 3DS: These are the old files of 3D Studio (MS-DOS versions)

• IPT and IAM: These are the Autodesk Inventor parts and also the assembly files

• MODEL, SESSION, EXP, DLV3, CATPART, and CATPRODUCT: These are the CATIA files

• IJ: These are the JT solid modeling files

• X_B, X_T: These are both Parasolid binary and Parasolid text files

• PRT, ASM, G, and NEW: These are the Pro/Engineer files

• 3DM: These are the Rhino files

• PRT, SLDPRT, ASM, and SLDASM: These are the SolidWorks files

• STE, STP, and STEP: These are the STEP files

The IMPORT command (alias IMP) allows importing several file types. The EXPORT command (alias EXP) allows exporting the model or selected objects to several file types.

Exporting to 3ds Max

3ds Max and 3ds Max Design are the 3D Autodesk software for creating high-quality images and animations. Many users prefer to model in AutoCAD and then export to 3ds Max for applying materials, lights, defining animations, and render. Many others want to import a 2D drawing and create the 3D model on top of it.

The best file formats to communicate with 3ds Max are DWG and FBX.

There are some basic precautions that must be taken when working on an AutoCAD model if this is going to be imported to 3ds Max:

• The model must not have lost objects far away. The ZOOM extents before saving is always a good advice.

• It is also wise to purge the drawing for not taking useless information.

• The model must be placed near the origin of the world coordinate system. When opening in 3ds Max, this program places the model that is related to the world coordinate system, which is independent of the current UCS when saving the model in AutoCAD. If objects are too far from the origin, we will have huge problems in Max.

• It is completely forbidden to have overlapping objects.

• The AutoCAD model should have a good layer distribution, as the normal method in Max is to import each layer's objects as one Max object (as editable spline or editable mesh). As applying materials in Max is normally done by an object. Also if layer distribution contemplates this, it will be much easier to apply materials in Max.

Exporting to Revit

Revit is a 3D Autodesk software suite encompassing the following three programs:

• Architecture: This is used to project 3D architecture models

• MEP: This is used to project mechanical, electrical, and plumbing

• Structure: This is used to project building structural elements

It is possible to import 3D models in Revit and convert them into Revit objects, such as mass elements.

The best file formats to communicate with Revit are DWG and SAT.

We present some tips to prepare AutoCAD models:

• One layer must be given to each material (in Revit, materials are applied to layers, identified by object styles).

• Units must be consistent.

• An AutoCAD object's properties, such as color and linetype, must be ByLayer, so these can be modified in Revit. If objects have explicit colors or linetypes, it is not possible to modify them.

• AUDIT and PURGE should be performed before saving or exporting to SAT.

Clues for development

To be an excellent 3D modeler in AutoCAD, it is important to know all commands and concepts well, but the most important is practice, practice, and practice.

Here are some final advices for development:

• Before starting in 3D, the model must be understood well.

• All model dimensions must be known or easily decided (if we are creating something new). We may consider creating some volumes just to decide general dimensions.

• Where to start a 3D model must be planned well. Frequently a wrong start represents hours or days of lost work.

• Output is also important as it may influence the modeling. For instance, if it is for rendering, it may not need important details in far parts of the model; when creating models for prototyping in stereo lithography, the model must be a single mesh and cheaper to produce if hollowed.

• If the project includes 3D blocks, such as furniture or equipments, an Internet search may be performed, or the manufacturer may be contacted. These blocks, if found with a different file format, may be converted or imported.

• All materials must be selected to know at least that all parts have different materials. Distinct layers must be applied to all parts with different materials.

• Projects must be saved frequently in specific and organized folders. Some backups or files that are currently in use must be maintained so that the current model file can be recovered if it gets corrupted.

• Complex models should not be avoided. It's with challenging models that we progress and learn how to extract the maximum from AutoCAD.

• External references (xrefs) may be considered in order to split complex models.

• Free time can be used to create complex models; we may launch challenges to ourselves.

• The AutoCAD workspace can be customized. Instead of relying on the ribbon, a more efficient and fast way to work is configuring shortcuts or creating specific toolbars.

• The Internet, namely forums and blogs, are great sources of information and must be consulted regularly. We learn a lot with others' questions and comments; we may also ask for advice or support.