Validation of CG Models - An Introduction to Computer Graphics for Artists - page 136

Fig. 9.26 The videocassette model in this illustration is translated away from the origin

industry standard is to have the front of your object facing positive-Z and to have its
center or bottom center located on the global origin.
This error is not uncommon for inexperienced artists, but it can be very irritating,
especially for animators because their animation depends on a correct, untranslated
start position.

9.4.8 Self-penetration

If any part of your object penetrates itself such as an over-rotated wall, then it should be
adjusted (Fig. 9.27 ). There is an exception to this, and that is when penetration is done
for the purpose of optimization and it does not result in partial or fully coincident faces.

9.4.9 Separated Faces

If you separate a part of your model so that you can adjust its orientation without
distorting it, but forget to add it back to the original polyset, you will have separated
faces (Fig. 9.28 ) . This can lead to animation errors where some of your model is left
behind after a translation.

9.4.10 Spikes

Spikes usually occur when you move a single vertex while intending to move
another one. This is the result of careless selection. Artists should verify their selec-
tions before moving them, to prevent this kind of error. A Spike is a vertex that has
been pulled away from the main body of the model, without detaching it (Fig. 9.29 ).