廣季-Itsfoundthattoreducethedistortion,itisimportantfortheseamtopassthroughthevariousso-called“extrema"（极值点）- Although extrema can be foundaccurately,itis stilldifficulttoguidetheseamthroughtheseextrema2009.3.30Tsinghua University
– It’s found that to reduce the distortion, it is important for the seam to p g ass throu gh the various so-called “extrema”(极值点). – Althou gh extrema can be found accurately, it is still difficult to guide the seam through these extrema. the seam through these extrema. Tsinghua University 2009. 3.30
廣号Theobjective(目标)is to consider seam computation with givenextremalvertices(wecalledextrema(极值点）2009.3.30Tsinghua University
The objective(目标), is to consider seam computation with given is to consider seam computation with given extremal vertices (we called extrema(极值点)). Tsinghua University 2009. 3.30
廣琴2. Related WorkTo seek a good seam, we should follow twostrategies(策略）The seam should pass through all extremal verticesThe seam'slength shouldbeminimum(最小）2009.3.30Tsinghua University
2 Related Work 2. Related Work • To seek a good seam, we should follow two strategies(策略): – The seam should pass through all The seam should pass through all extremal vertices extremal vertices. – The seam’s length should be minimum( The seam’s length should be minimum(最小). Tsinghua University 2009. 3.30
廣翠-Forgivenextremalvertices,Tofindaminimumlengthseamconnecting all extremal vertices comesdowntothe Steiner Tree problem in Graph Theory. For a givenweighted graph,it's aNP-completeproblem-Twomain approximated algorithm for it are Minimumspanning tree (MST)method and GreedyalgorithmShefferandGuusethosetwomethodsforseamcomputingrespectively2009.3.30Tsinghua University
– For given extremal vertices, To find a minimum length seam connecting all extremal vertices comes down to seam connecting all extremal vertices comes down to the Steiner Tree problem in Graph Theory. For a given weighted graph, it weighted graph, it s’ a NP -complete problem. complete problem. – Two main approximated algorithm for it are Minimum spanning tree (MST) method and Greedy algorithm spanning tree (MST) method and Greedy algorithm. Sheffer and Gu use those two methods for seam computing respectively computing respectively. Tsinghua University 2009. 3.30
廣翠Guetal.“GeometryImage（几何图像）-Guetal.firstfindaninitial cutthatopensmeshM intoa disk.-Extremawasfoundbyutilizingtheshape-preservingfeatureofFloater'sparameterizationwhenanewextremalvertexisdetected,the shortestpathbetween the current seam and the new extremalvertex is added to the seam2009.3.30Tsinghua University
• Gu etal. “Geometry Image” (几何图像 ) – Gu et al first find an initial cut that opens mesh Gu et al. first find an initial cut that opens mesh M into a disk. – Extrema was found by utilizing the shape Extrema was found by utilizing the shape -preserving preserving feature of Floater's parameterization. – when a new extremal vertex is detected, the shortest path between the current seam and the new extremal vertex is added to the seam. Tsinghua University 2009. 3.30