Optimizing 3D crates

During the third week of our 3D computer graphics course the task given to the students was to optimize and look for errors on the 3D crates created the week before. We were assigned to first optimize one crate from two other students during class and later optimize our third crate at home. The two students who worked on one of my crates each were Rebecka Nyström (http://islandgamelog.wordpress.com) and Camilla von Paykull (http://c4mi.blogspot.se).

Cartoony

The student working on my cartoony crate was Rebecka and the before and after screenshots are presented below.

                      Before                                                                        After

The one error found in my cartoony crate was that it had 30 overlapping faces on each bottom corner of the crate, which are highlighted in green. This must have happened when I used the extrusion tool to create more of an interesting shape on the top of the crate’s four legs. When I extruded the shapes more edges, vertices and faces were created. This is the reason why the model has so many overlapping faces because a face was created on top of an already existing face.

One simple way to fix this is by just selecting the overlapping polygon and moving it away from the other face ever so slightly. Although this method is simple, it wouldn’t be the most optimal solution if you are doing 3D models for games. Faces that won’t be seen to the player will still be rendered. This is unnecessary because needless faces will be rendered and its uneconomical as well if you are on a strict poly budget, like most games are. You might think that this is just one model and it won’t make a big difference, but most games use their models over and over again to save time and money and that’s when this method would become a problem.

The other way to do this is by stitching available vertices together and editing the wireframe a bit, which was the method Rebecka chose. She has deleted the edges and vertices that didn’t really do anything for the shape (marked with red) and later connected the available edges with its vertices together (marked in blue). This method was the better choice because now the extruded shapes are stitched to the main shape and the overlapping faces were discarded.

Sci-fi

My sci-fi crate was optimized by Camilla and below you can see the before and after screenshots.

          Before                                                                       After

The major problem with this crate was that the extruded parts on the bottom and on the top weren’t stitched correctly. New vertices that basically did nothing for the shape were created at each side where I had used the extrusion tool (marked in blue). To solve this Camilla just basically connected the loose vertices together with edges without creating any new n-gons. Every vertex in a 3D model should do something otherwise its simply useless.

The minor problem with this crate was that it had 2 overlapping vertices (marked with a red dot) that created several overlapping faces. By just welding the vertices together she solved the issue with overlapping faces at the same time.

Post-apocalyptic

The post-apocalyptic crate was later optimized by me after class. Once again both before and after shots are presented below.

               Before                                                                     After

The problem this model had was that the face orientations on some of the shapes (marked with red arrows) decorating the main box were off. This happened because when I wanted to decorate my crate with more broken and twisted shapes I mirrored an already existing shape instead of making new an object from scratch. I fixed this by selecting the shapes with the face orientation problem and flipped its polygons.

There were also quite a lot of overlapping vertices within this crate. This must have occurred when I made an inset and later beveled. If I’m not pleased with the bevel I created then I undo and redo until I believe it’s where I want it to be. For some reason, the undoing and redoing causes 3Dsmax to leave vertices behind. I don’t know if it’s a common problem for 3Dsmax or if it’s just in my version. This is certainly not the first time this has happened. I solved it by welding the vertices 2 at a time until there was no overlapping.

Conclusion

When working with 3D models you do have to be mindful of the edge flow and wireframe the model is going to have, and especially when using tools like extrude. Tools like that create new vertices, edges and faces that sometimes do nothing for your shape so you do have to be aware of how to stich it properly afterwards to avoid later rendering problems. Every vertex has to do something and that is what I will keep in mind for my future 3D modelling work.