Game Development Reference
In-Depth Information
Vector displacement
Conventional displacement
Figure 16.1.
Conventional displacement (black) in comparison with vector displacement
(gray).
16.2 Overview: Vector Displacement
Unlike conventional displacement maps, a VDM stores distance data as well as
di-
rectional
data(see
Figure16.1
)
.Basedonthepixel-colorvalueofthemapimage,
a VDM stores the height, or distance, a vertex will be displaced and the direc-
tion of the vertex displacement [Autodesk 10]. This allows for complex geometric
structures, such as overhangs and undercuts, to be stored in a 2D image format.
16.2.1 Mudbox and Vector Displacement
Vector displacement mapping in
Mudbox
provides a very powerful toolkit that al-
lows displacement data to be stored as a 32-bit (per channel) floating-point color
image and captures all of the detail from a mesh without any loss in quality from
the original sculpted detail. The maps accurately record complex sculpted fea-
tures that undercut, overhang, or occlude other detail on a model. Provided
that the UV-coordinates are laid out eciently, 32-bit displacement maps can
record 4,294,967,295 unique height data as floating-point values.
Mudbox
stores the
XYZ-coordinate data in the RGB values of the image, where X=red, Y=blue,and
Z=green. The maps are extracted in 32-bit (per channel) floating-point TIFF or
OpenEXR format, or as a Ptex file (with the Autodesk Mudbox 2011 Subscription
Advantage Pack).
Map creation and extraction in Mudbox.
Allowing for the storage of geometric
data in an image format, VDMs are easily and quickly created in Mudbox. Sculpted
details are extracted to a map by recording the directional and distance data (as a
color value) between user-specified subdivision levels from a source and target mesh
(i.e., between the top-level subdivision resolution and the base mesh). Similar to
the process of extracting conventional displacement, VDMs can be extracted in
resolutions of up to 8K. The subdivision map extraction process (recording the dis-
