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Many different quality measures have been defined for graph drawings, in an attempt to find objective means of evaluating their aesthetics and usability. In addition to guiding the choice between different layout methods for the same graph, some layout methods attempt to directly optimize these measures.

Many different quality measures have been defined for graph drawings, in an attempt to find objective means of evaluating their aesthetics and usability. In addition to guiding the choice between different layout methods for the same graph, some layout methods attempt to directly optimize these measures.

[[File:4node-digraph-embed.svg|upright=0.5|thumb|

[[File:4node-digraph-embed.svg|upright=0.5|thumb|

*The [[Area (graph drawing)|area]] of a drawing is the size of its smallest [[bounding box]], relative to the closest distance between any two vertices. Drawings with smaller area are generally preferable to those with larger area, because they allow the features of the drawing to be shown at greater size and therefore more legibly. The [[aspect ratio]] of the bounding box may also be important.

*The [[Area (graph drawing)|area]] of a drawing is the size of its smallest [[bounding box]], relative to the closest distance between any two vertices. Drawings with smaller area are generally preferable to those with larger area, because they allow the features of the drawing to be shown at greater size and therefore more legibly. The [[aspect ratio]] of the bounding box may also be important.

一个图形的面积是它的最小'''<font color="#ff8000">边界盒 Bounding Box</font>'''的大小，相对于任意两个顶点之间的最近距离。面积小的画通常比面积大的画更可取，因为它们可以让图画的特征以更大的尺寸显示，因此更清晰。边界框的纵横比也很重要。

一个图形的面积是它的最小'''<font color="#ff8000">边界盒 Bounding Box</font>'''的大小，相对于任意两个顶点之间的最近距离。面积小的画通常比面积大的画更可取，因为它们可以让图画的特征以更大的尺寸显示，因此更清晰。边框的纵横比也很重要。

*Symmetry display is the problem of finding [[Graph automorphism|symmetry group]]s within a given graph, and finding a drawing that displays as much of the symmetry as possible. Some layout methods automatically lead to symmetric drawings; alternatively, some drawing methods start by finding symmetries in the input graph and using them to construct a drawing.<ref>{{harvtxt|Di Battista|Eades|Tamassia|Tollis|1994}}, p. 16.</ref>

*Symmetry display is the problem of finding [[Graph automorphism|symmetry group]]s within a given graph, and finding a drawing that displays as much of the symmetry as possible. Some layout methods automatically lead to symmetric drawings; alternatively, some drawing methods start by finding symmetries in the input graph and using them to construct a drawing.<ref>{{harvtxt|Di Battista|Eades|Tamassia|Tollis|1994}}, p. 16.</ref>

*[[Angular resolution (graph drawing)|Angular resolution]] is a measure of the sharpest angles in a graph drawing. If a graph has vertices with high [[degree (graph theory)|degree]] then it necessarily will have small angular resolution, but the angular resolution can be bounded below by a function of the degree.<ref name="ps09">{{harvtxt|Pach|Sharir|2009}}.</ref>

*[[Angular resolution (graph drawing)|Angular resolution]] is a measure of the sharpest angles in a graph drawing. If a graph has vertices with high [[degree (graph theory)|degree]] then it necessarily will have small angular resolution, but the angular resolution can be bounded below by a function of the degree.<ref name="ps09">{{harvtxt|Pach|Sharir|2009}}.</ref>

'''<font color="#ff8000">角度分辨率 Angular Resolution</font>'''是图形绘制中最小的锐角的度量。如果一个图的顶点高度高，那么它的角分辨率就会很小，但是角分辨率可以由角的函数来限定。

'''<font color="#ff8000">角度分辨率 Angular Resolution</font>'''是图形绘制中最小的锐角的度数。如果一个图的顶点高度高，那么它的角分辨率就很小，但是角分辨率可以由角的函数来限定。

*The [[slope number]] of a graph is the minimum number of distinct edge slopes needed in a drawing with straight line segment edges (allowing crossings). [[Cubic graph]]s have slope number at most four, but graphs of degree five may have unbounded slope number; it remains open whether the slope number of degree-4 graphs is bounded.<ref name="ps09"/>

*The [[slope number]] of a graph is the minimum number of distinct edge slopes needed in a drawing with straight line segment edges (allowing crossings). [[Cubic graph]]s have slope number at most four, but graphs of degree five may have unbounded slope number; it remains open whether the slope number of degree-4 graphs is bounded.<ref name="ps09"/>