Add a narrative intro explaining what PySurfer is

Author: mwaskom

doc/index.rst

@@ -14,6 +14,7 @@ More Information
 .. toctree::
     :maxdepth: 1
 
+    intro
     install
     examples/index.rst
     documentation/index.rst

doc/intro.rst

@@ -0,0 +1,37 @@
+.. _intro:
+
+What is PySurfer?
+=================
+
+PySurfer is a Python library and application for visualizing brain imaging
+data. It is specifically useful for plotting data on a three-dimensional mesh
+representing the cortical surface of the brain. If you have functional MRI,
+magnetoencephalography, or anatomical measurements from cortex, PySurfer can
+help you turn them into beautiful and reproducible graphics.
+
+PySurfer uses an explicit model of cortical geometry to generate
+highly-accurate images of neuroimaging data. This is preferable to other
+approaches that use simple 3D renderings of a brain volume because the
+underlying topology of the cortex is a two-dimensional sheet.  PySurfer can
+read cortical models that have been processed using Freesurfer_ to "inflate"
+the cortical folds and reveal activations that are buried within deep sulci.
+This presentation is much closer to how cortical areas are laid out, and it can
+help you understand and communicate your efforts to map functional or
+morphometric organization.
+
+PySurfer and its dependencies are written in Python and released with a liberal
+open source license. PySurfer can be combined with other tools from the nipy_
+ecosystem to manipulate and plot data in the same script or interactive
+session. The visualization is primarily controlled with a high-level API that
+allow you to draw a complex scene with just a few lines of code. This means
+that PySurfer is naturally scriptable. Once you have developed a basic
+visualization, it's easy to add a for-loop and generate the same image for
+every subject in your experiment. It also aids the reproducibility of graphics
+you create for conferences or papers, as each figure can be associated with a
+short script that shows exactly how the visualization was produced.
+
+To see a set of examples demonstrating some of PySurfer's capabilities, you can
+check out the :ref:`example gallery <examples>`.
+
+.. include:: links_names.txt
+

examples/README.rst

@@ -1,3 +1,5 @@
+.. _examples:
+
 PySurfer Example Gallery
 ========================
 

examples/index.rst

@@ -1,3 +1,5 @@
+.. _examples:
+
 This page offers a set of example scripts intended to demonstrate the
 functionality offered by PySurfer, from the most basic tasks to more complex 
 visualizations.