Render as a surface added to point cloud 2D renderers (qgis#9050)

docs/user_manual/working_with_point_clouds/point_clouds.rst

@@ -239,6 +239,10 @@ If you do not know the attributes of the point cloud, the |basicStatistics|
 overview of which attributes are contained in the point cloud and in which
 ranges the values are located.
 
+For each renderer, you can improve the data display
+adjusting the :ref:`point symbol size <pointsymbol_size>`
+or enabling :ref:`surface triangulation <pointcloud_rendersurface>`.
+
 .. _figure_point_cloud_symbology_overview:
 
 .. figure:: img/point_cloud_symbology_overview.png
@@ -340,6 +344,13 @@ also configure:
 RGB Renderer
 ^^^^^^^^^^^^
 
+.. _figure_point_cloud_rgb:
+
+.. figure:: img/point_cloud_rgb.png
+   :align: center
+
+   The point cloud RGB renderer
+
 With the |multibandColor| :guilabel:`RGB` renderer, three selected attributes
 from the point cloud will be used as the red, green and blue component. If the
 attributes are named accordingly, QGIS selects them automatically and fetches
@@ -354,12 +365,13 @@ A :guilabel:`Contrast enhancement` method can be applied to the values:
   If you have problems with it, you should use the default setting
   :guilabel:`Stretch to MinMax`.
 
-.. _figure_point_cloud_rgb:
 
-.. figure:: img/point_cloud_rgb.png
+.. _figure_RGB_render_surface_example:
+
+.. figure:: img/RGB_render_surface_example.png
    :align: center
 
-   The point cloud RGB renderer
+   Example of RGB renderer (left) combined with surface triangulation option (right)
 
 
 .. _point_cloud_classification:
@@ -418,6 +430,13 @@ classes generated by QGIS:
    In the :guilabel:`Layers` panel, you can right-click over a class leaf entry of a layer
    to quickly configure visibility of the corresponding features.
 
+.. _figure_clasification_render_surface_example:
+
+.. figure:: img/clasification_render_surface_example.png
+   :align: center
+
+   Example of classification renderer (left) combined with surface triangulation option (right)
+
 .. _pointsymbol_size:
 
 Point Symbol
@@ -427,6 +446,29 @@ Under :guilabel:`Point Symbol`, the size and the unit (e.g. millimeters,
 pixels, inches) with which each data point is displayed can be set.
 Either :guilabel:`Circle` or :guilabel:`Square` can be selected as the style for the points.
 
+.. _pointcloud_rendersurface:
+
+Render as a surface (Triangulate)
+.................................
+
+Check |checkbox| :guilabel:`Render as surface (Triangulate)` to enable the triangulation
+of the point cloud layer in the 2D view. This option allows rendering triangles instead of points.
+Each point keeps its color for interpolation in the triangle.
+You can control the horizontal length of computed triangles:
+
+By checking the |checkbox| :guilabel:`Skip triangles longer than` option and setting up
+the threshold value, you can control the maximum lenght of a side of the triangles
+to consider in the horizontal plan. This can be particularly useful if you want to
+identify actual holes in the data. 
+
+.. _figure_shading_render_surface_example:
+
+.. figure:: img/shading_render_surface_example.png
+   :align: center
+
+   Rendering data as a surface with map shading (left) and with map shading, filtering large triangles (right)
+
+
 Layer Rendering
 ...............