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986 Appendix B: Troubleshooting 3ds Max
Problems Ca used by Unit S ettings
The unit settings of a model can often get you into
trouble. Understanding some of the common
problems can help you a void them.
This section addresses the two m ost common
problems that modelers encounter.
Problems and Resolutions
Objects Disappear When the Camera Gets Close
This situation can happen when you model
thingsonaverytinyscaleandthenhavetoget
very close to them in a Camera or Perspective
viewpor t. Architectural walkthrough animations
are notorious for this kind of behavior. You’ve got
acameramovingalongapathandatsomepointit
gets too close to a wall and you’re suddenly able to
see through to a room on the other side.
Note: This problem is quite common for designers
working with the metric system when you want
to use real world metric units and you change the
System Unit Scale to 1 unit=1 meter. You don’t
have to change the System Unit Scale to metric to
work in Metric units; just change the units.
There are two solutions that often fix this problem.
Turn on the manual viewport clipping:
You can turn on the manual v iewport clipping and
adjust it to see the entire object. Viewpor t clipping
has a Near and Far range setting , if a camera gets
closer to an object than the Near Clip value, you
w ill see through that object. Likewise, objects
that are located beyond the Far Clip value, will be
invisible to the camera.
1. Open the problematic scene and select the
camera.
2. In the Parameters rollout > C lipping Planes
group, turn on Clip Manually.
3. Adjust the Near or Far Clip value, or both.
When you can see the object again, your
clipping plane is set properly.
Scale t he entir e scene:
Ifitdoesn’tmatterwhatunitsyouworkin,scale
theentirescenesoobjectsarenotaffectedby
view por t clipping.
1. Open the problematic scene and select
everything.
2. On the toolbar, click Select And Uniform
Scale.
3. Enlarge the entire scene.
Not only do the objects in the scene get larger
but the distance between objects increases. So,
the larger you scale the scene, the further your
camera is located f rom the surrounding objects.
If you need to work in real world units, such as
inches or meters, you should set the scale of the
scene before you begin modeling by changing
theSystemUnitScalevaluefromthedefaultof1
unit=1 inch to something like 1 unit=0.1 inch or
even 0.01 inch.
IfyouchangetheSystemUnitScaleafteryouhave
begun modeling, you wi ll need to use the Rescale
World Units utilit y to rescale the scene.
Zooming and Panning Are Too Fast or Slow
If zooming and panning are too fast or too slow,
the most likely cause is the System Unit Scale.
3ds Max can exhibit round-off errors when dealing
with extremely large or small distances. These
round-off errors can also cause normals to be
flipped or strange v iewport clipping. 3ds Max
does not h ave the numerical resolution to zo om
infinitely from the some remote corner of the solar
system dow n to an ant on your doorstep.
If you’re going to change the System Unit Scale, you
should change it before beginning any modeling.
Ifyoudohavetosetitlater,it’sbesttorescale