+\anchor blsurf_attractor
+<h2>Advanced maps</h2>
+\n
+\image html blsurf_parameters_sizemap2.png
+\n
+More specific size maps can be defined on faces.
+
+<ul>
+<li> <i> Attractors </i> allow to define the size of the mesh elements on a face so that the mesh is the finest on the attractor shape and becomes coarser when getting far from this shape.
+<ul>
+<li> The selected attractor can be a Vertex, an Edge, a Wire or a Compound mixing several entities of those types.</li>
+<li> The attractor doesn't have to be a sub-shape of the shape to mesh.</li>
+<li> The size will grow exponentially (see formula below) but is bounded by gradation, \n so if you want the formula to be strictly respected, you should set the <i>gradation</i>
+to its maximum (2.5) in the <i>arguments</i> tab.
+</ul>
+\n
+<li> Furthermore you can choose to <i> keep the size constant </i> until a certain distance from a shape. This option can be combined or not with an <i>attractor</i> size map described above.
+<ul>
+<li> If the two options are combined the size will remain constant until the distant specified in "constant over" and grow then as prescribed by the attractor function.</li>
+<li> Else the growing is only controled by the standard arguments of BLSURF (gradation ...).</li>
+</ul>
+</ul>
+
+\image html blsurf_attractors2.png "Example of mesh created using attractors, the attractors here are the side edges and the size grow from the side of the surface towards the apex"
+\n
+\image html blsurf_const_size_near_shape2.png "Example of size map with constant size option, the size is kept constant on the left side of the surface until a certain distance"
+\n
+Remark : The validation of the hypothesis might take a few seconds if attractors are defined or the "constant size" option is used because a map of distances has to be built on the whole surface for each face where such an hypothesis has been defined.
+
+<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
+