Introduction
Simplygon was developed and released in 2007 with one single purpose, to simplify and optimize complex 3d meshes. Whether used to create LOD models for games or to crunch a heavy model for transporting over the Web, the original program succeeded in this goal and now a couple of years later, the developers at Donya Labs have recently released version 2.8 of the software.
The new version includes a number of improvements including support for the Collada format, a plug-in for 3ds Max, and the release of an versatile SDK that can be used to integrate the Simplygon technology into your favorite software tools.
The Simplygon GUI
Once licensed, Simplygon ships with a stand-alone application that can be used in lieu of a plug-in. The Simplygon program is incredibly easy to use. The interface includes buttons for loading and saving models, several standard buttons for changing the render view including vertices, normals, wireframe, shaded, textures with a checkerboard pattern and textured. You can also switch between the standard viewpoints such as Top, Bottom, Left, Right, Front, Back and Perspective.
The Simplygon application can load in meshes saved in either the Wavefront (OBJ) and the Collada (DAE) formats. This is a limited set of formats, but the SDK allows you to build support for any format you'd like.
The model can be manipulated in the view window using the left (rotate), right (zoom) and middle (pan) mouse buttons allowing you to focus in on specific areas of the mesh. The interface also features a split-screen mode that lets you see in real-time the mesh before and after being optimized (Figure 1).
Figure 1: When split-screen mode is turned on, you can see the results of the optimization in real-time.Decimation Mode
To the right of the view window are two panels that hold all the various optimization settings. The first of these is Decimation mode. This mode is the standard reduction mode. It allows you to specify the mesh reduction based on the pixel size of the object (which is great for LOD work), the total number of triangles in the mesh, or within a given distance value. There is also an option to prevent any intersections between nearby polygons during the reduction process.
Within the Repair section are options to weld all vertices within a given tolerance. There is also an option to eliminate any T-junctions, which happens when three edges meet at a single vertex. This can cause rendering problems if allowed. These repair options are helpful by themselves even if you don't want to reduce the polygon count of a model.
The Decimation panel also includes options to preserve the existing texture, UV coordinates, and object boundaries. The panel includes a slider that you can dial in the fidelity of these features between Low and High.
The Normal Recalculation option lets you specify an angle beyond which normals are not averaged.
After selecting the optimization settings, you can process the loaded mesh by clicking on the large S button located under the panels. Once processed, the total triangle count, object diameter and estimated pixel diameter are listed under the S button. You can also manipulate the mesh with the split-screen option enabled to compare the resulting optimization with the original mesh.
Figure 2 shows a high resolution mannequin mesh that was reduced from 52, 000 polygons to just over 1000 polygons in just over 10 seconds.
Figure 2: Not only is the quality of the reduction very good, but Simplygon also works incredibly fast.
Remeshing Mode
The second optimization mode is found in the second panel to the right of the view window and allows remeshing. This mode uses the existing mesh to create an entirely new mesh object. The remeshing process is based on a final Onscreen Size value, which is the maximum diagonal pixel size of the final remeshed object.
Since the remeshing process is based on the screen size, the Simplygon program realizes dramatic reductions by eliminating interior objects, filling holes and re-texturing the model using normal casting algorithms. Within the Remeshing panel are options to specify the quality, size and sampling of the recalculated texture map. You can also include the path to normal and occlusion maps if the original model uses one.
I had trouble testing the remeshing capabilities in the stand-alone application because it kept crashing on me.
SDK
The Simplygon stand-alone program is an example of what is possible with the included SDK. It ships with full source code and doesn't necessarily include all the features available in the SDK. The SDK includes a robust C++ API for Windows XP, Vista and Linux slam64. It also includes full documentation, samples and tutorials.
3ds Max Plug-in
Simplygon ships with a plug-in to 3ds Max. The plug-in utility allows reduction of multiple selected objects and it even supports skinning information. The plug-in works in Max 9, 2008, 2009 and 2010 in both 32- and 64-bit versions, as shown in Figure 3.
Figure 3: The 3ds Max plug-in lets you use the Simplygon technology directly in Max.
Summary
Simplygon is very good at what it does. It optimizes 3d mesh objects quickly and lets you see and manipulate the results in real-time, which is helpful if you want to check for problems before saving out the results. The stand-alone interface is simple, but gave me problems with regular crashes.
The 3ds max plug-in allows immediate benefit for existing workflows or you can use the SDK to integrate the technology into your pipeline if you use some other tool.
Simplygon version 2.8 is available for both 32- and 64-bit versions of Windows XP and Vista. It is also available for Linux slam64.
Kelly L. Murdock is the president of Tulip Multimedia, a design firm specializing in 3d graphics. He is the author of multiple computer books including the 3ds Max Bible and the Creative Suite Bible.
As for me, I use the technologies of the pseudo-3D, stitched from simple photos to a 3D rotating object. Yes, it could not be used for 3D graphics but it can be shown on your website or you can send the stitched object to your friends, as I do ;)
