have you tried to cross product the normal with the first neigbhor edge direction? you can eventually do a quick propotype in ICE to see if that is matching.
Cheers. -A ----------------------------------------------- Ahmidou Lyazidi Director | TD | CG artist http://vimeo.com/ahmidou/videos http://www.cappuccino-films.com 2013/12/6 Daniel Brassard <[email protected]> > Oops, should had read your last sentence, moving on. > > > On Thu, Dec 5, 2013 at 8:21 AM, Daniel Brassard <[email protected]>wrote: > >> Is a cross product between the normal and tangent vectors not giving you >> the bi-normal vector? >> >> >> >> On Wed, Dec 4, 2013 at 6:50 PM, Matt Lind <[email protected]>wrote: >> >>> Those calculations are for converting the normal in the normal map >>> between color and euler space. The normal stored in the normal map needs a >>> basis (ie: transform matrix) to act as a frame of reference so the renderer >>> knows how to orient the normals in the map to the topology . That basis is >>> derived from information in the Texture UV space, geometry normal, and >>> Tangents and BiNormals vertex color properties. >>> >>> >>> >>> I need the algorithms for the computation of the basis, and I need to >>> know how ultimapper compensates for the case when the binormals are not >>> present. For example, does ultimapper assume the basis will always be >>> orthogonal and do a cross product of the tangent and geometry normal to >>> generate the binormal? >>> >>> >>> >>> >>> >>> Matt >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> *From:* [email protected] [mailto: >>> [email protected]] *On Behalf Of *francisco criado >>> *Sent:* Wednesday, December 04, 2013 3:36 PM >>> *To:* [email protected] >>> *Subject:* Re: tangent/binormal space computation >>> >>> >>> >>> Hi Matt, >>> >>> will this help? >>> >>> >>> http://softimage.wiki.softimage.com/xsidocs/tangents_binormals_SettingtheDataTypeforTangentsandBinormals.htm#Rga95703 >>> >>> >>> >>> Francisco. >>> >>> >>> >>> 2013/12/4 Matt Lind <[email protected]> >>> >>> I need to write a variant of ultimapper to support our proprietary >>> workflows, but our content (tangent space normal maps) currently uses the >>> softimage standard. I need to know the algorithms Softimage uses so I can >>> make an accurate conversion to our proprietary standards. >>> >>> >>> >>> Specifically, I need to know: >>> >>> >>> >>> - how the vectors are computed in the Tangents and BiNormal vertex color >>> properties >>> >>> - how Ultimapper does a tangent space normal transfer when only a >>> Tangents vertex color property exists on the hi res mesh. >>> >>> (eg; what assumptions does it make / what calculations >>> does it do to compensate for lack of binormals?) >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> Matt >>> >>> >>> >> >> >
