8
System Unit Setup Dialog 893
TheUSStandardsareasfollows:
• Fractional Inches
• D ecimal Inches
•FractionalFeet
• D ecimal Feet
• Feet w/ Fractional Inches
• Feet w/ Decimal Inches
For the last two items, you can specif y w hich unit
isassumedwhenyouenteravalueinanumeric
field and press ENTER without including a units
specifier, such as ’ for feet or " for inches.
For example, if Feet is the default, typing 5
followed by ENTER results in 5 feet. Typing 5"
followed by ENTER results in 0’5". If Inches is the
default, typing 5 followed by ENTER results in
0’5". Ty ping 5’ followed by ENTER results in 5 feet.
Custom—Fill in the fields to define a custom unit
of measurement.
Generic—This is the default option (one inch) and
is equal to the system unit used by the software.
Lighting Units group
The Lighting Units group lets you choose
whether light values are displayed in American or
International units.
System Unit Setup Dialog
Customize > Units Setup > Click System Unit Setup.
This dialog appears w hen you click System Unit
Setup in the
Units Setup dialog (page 3 –891)
.
Wa rn in g: You should only change the system unit value
before
importing or creating geometry. Do not chan ge
the system unit in an existing scene.
Because of the nature of digital floating-point
calculations, distances that are extremely large
or extremely small can cause round-off error.
Symptoms of round-off error include trouble
navigating (zooming and panning become too fast
or too slow), unwanted viewp ort clipping, and
unexpected flipping of normals. Here are some
general guidelines to avoid the se problems:
• Make sure your scene is roughly centered
around the origin (0,0,0).
Round-off error increases at large distances
from the origin.
• Makesurenosignificantdetailinthesceneis
smaller than one generic 3ds Max unit.
Note: The
Rescale World Units utility (page 2–49)
alters the scale of world units throughout the entire
scene, or selected objects.
Procedure
To change the system unit:
1.
Choose Customize menu > Units Setup.
2. Click System Unit Setup.
3. Change the System Unit Sca le va lue, and click
OK.
The system u nit is immediately reset. This
setting remains in effect until you change it.