8

Using Units 3
Usi ng Units
Units are the key to connecting the
three-dimensional world of 3ds Max with
the physical world. You define the units you want
to use from the
Units Setup dialog (page 3–891) .
Changing Di splay Units
When you change display un its, 3ds Max
displays measurements in the new unit for your
convenience. All dimensions are displayed in
the new unit. Essential ly, you’re using a n ew
"measuring stick." No object is changed in this
process. As in the phys ical world, objects in the
scene maintain their absolute size, regardless of
how you measure them.
Type-In Entry
When you enter any dimension, 3ds Max always
assumes the number you enter is expressed in
the current units. You can also enter a series of
numbers: 3ds Max then converts their sum into
the current unit. Here are some examples that
assume the current units are in centimeters:
• Whenyouenteradimensionof1’(oneUS
foot), it converts to 30.48cm.
• If you enter a series of numbers such as 14 286
175 (separated by spaces), the ser ies is totaled
to 475.0cm.
• If you enter 1’ 1 (one US foot and 1 centimeter),
this is converted and summed into 31.48cm.
When you use US Standard as the display unit
scale, you can select either feet or inches as the
default for type-in entry. If you select feet and
enter 12, the result is 12’ 0". However, if you enter
1’ 2, the s oftware identifies t he second dig it as
inches, producing 1’ 2" as the result.
In any unit system, you can enter fractional
amounts. For example, assume you’re working in
US Standard with feet as the default:
• If you enter 18/3, the result is 6’0".
• If you enter 18/3", the result is 0’6".
• Youcanspecifyunitsinadifferentsystem,and
they are converted on the fly. F or example, if
you enter 18/3cm, the result is 0’2.362".
Understa nding the Sy stem U nit
3dsMaxkeepstrackofallmeasurementsinits
own internal system unit. No matter what kind
of display units you use, measurements are stored
in this absolute unit for storage and computation.
The default system unit is defined as 1.000 inch.
Aslongasthesystemunitisleftatoneinch,you
can freely share models and change units on the fly
with no effect on the underlying geometry. Except
in rare circumstances, you never need to change
this default scale. This means you c an merge a
model created with any standard unit into your
scene at t rue scale.
You c an change the system unit s etting on the
System Unit Setup dialog, available from the
Units Setup dialog (page 3–891) . Changing the
system unit is recommended only if your scene
hasverysmall(lessthanoneinch)orverylarge
dimensions. See
System Unit Setup Dialog (page
3–893)
for more information.
If you do need to change the system unit, change
it
before you create or import geometry. Do not
changethesystemunitinanexistingscene.