Michael: Bump Mapping is a technique that makes a surface appear uneven in some manner: bumpy, wrinkled, wavy etc. The basic idea is that instead of changing the color components in the illumination equation, we modify the surface normal by accessing a texture. The geometric normal of the surface remains the same; we merely modify the normal used in the lighting equation. This operation has no physical equivalent. We perform changes on the surface normal, but the surface itself remains smooth in the geometric sense.
There are two basic methods of modifying the normal with a bump map. One bump texturing technique uses two signed values b(u) and b(v) at each point. These two values correspond to the amount along the u and v image axes by which to vary the normal. These texture values, which typically are bilinearly interpolated, are used to scale two vectors that are perpendicular to the normal. These two vectors are added to the normal to change its direction. These two values essentially represent how steep the surface is and which way it faces its point. The second method uses a height field to modify the surface normal's direction. Each monochrome texture value represents a height, so white is a high area and black a low one (or the opposite). The heightf ield is used to derive u and v signed values similar to rhose used in the first method. --Rahul >From: "Michael P. McCutcheon" <[EMAIL PROTECTED]> >Reply-To: Discussion list for Java 3D API <[EMAIL PROTECTED]> >To: [EMAIL PROTECTED] >Subject: [JAVA3D] OT: What is bump mapping? What is cube mapping? >Date: Mon, 1 Oct 2001 18:27:15 -0700 > >What are these conecpts and what do they allow the programmer to do? > >Does Java3D support either of these concepts? > >Mike > _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
