Adding tutorials to the documentation.

documents/tutorials.dox

@@ -9,7 +9,7 @@ OSX's format.
 
 <h2>Fitting using the command line</h2>
 
-<h3>Rational interpolation</h3>
+<h3>1D Rational interpolation</h3>
 The \a data2brdf allows to perform a fitting procedure by converting a \ref
 data object into a brdf object (also named \ref function).
 
@@ -22,7 +22,7 @@ First, download the Kirby2 dataset in ALTA format: <a href="http://alta.gforge.i
 The result can be exported using the \a brdf2data commands.
 
 \verbatim
- $ ./build/data2gnuplot --input Kirby.brdf --output Kirby.dat --in-data ../data/1d/NIST/Kirby2/Kirby2.dat 
+ $ ./build/data2gnuplot --input Kirby.brdf --output Kirby.dat --in-data ../data/1d/NIST/Kirby2/Kirby2.dat
 \endverbatim
 
 The \a brdf2data allows you to export a function into a data file. If no data plugin is specified, the ALTA format is used which is gnuplot compliant. The position of evaluation for the function are taken from a specified data file (here the original Kirby2 file).
@@ -31,7 +31,7 @@ You should obtain gnuplot data files like the following image:
 
 \image html Kirby2.png
 
-To convert this brdf file to be used in another software (here matlab), 
+To convert this brdf file to be used in another software (here matlab),
 you will need the following command:
 \verbatim
  $ ./build/brdf2brdf --input Kirby.brdf --output Kirby.m --export matlab
@@ -44,6 +44,46 @@ distribution).
 
 <br />
 
+<h3>2D Rational interpolation of BRDFs</h3>
+
+In this example, we will show how to perform data conversion and vertical segments interpolation of the <em>gold-metallic-paint</em> material from the MERL database using the command line programs on an OSX platform. First download the binary file <a href="http:///">gold-met.binary</a> and copy it to the <em>$ALTA/data/3d/merl</em> directory.
+
+The first command we will execute will convert the three dimensional data in a 2D slice in the halfway vector parametrization:
+\verbatim
+ $ ./build/data2data --input ../data/3d/merl/gold-met.binary --in-data ./build/libdata_merl.dylib --output ../data/2d/merl/gold-met.exr --out-data ./build/lib
+\endverbatim
+
+The \a data_merl plugin permits to represent BRDF slices using HDR image files (.exr format). The output of this command should look like:
+
+\image html gold-met-merl.png "gold-metallic-paint slice"
+
+Then, we perform fitting of this 2D BRDF slice:
+\verbatim
+ $ ./build/data2brdf --input ../data/2d/merl/gold-met.exr --data ./build/libdata_brdf_slice.dylib --output gold-met.brdf --fitter ./build/librational_fitter_parallel.dylib --func ./build/librational_function_chebychev.dylib --min-np 60 -- np 100
+\endverbatim
+
+This outputs a BRDF file which cannot be displayed directly. To seen the result of our fitting, we can export this BRDF into the BRDF image slice format:
+\verbatim
+ $ ./build/brdf2data --input gold-met.brdf --output gold-met-rat.exr --data ./build/libdata_brdf_slice.dylib
+\endverbatim
+
+It is now possible to perform side by side comparison of the original data, and the interpolated rational function:
+
+<center>
+  <table  border="0" style='text-align:center'>
+  <tr>
+    <td>
+      \image html gold-met-merl.png "gold-metallic-paint slice"
+    </td>
+    <td>
+      \image html gold-met-rat.png "gold-metallic-paint slice fitting using R-BRDFs"
+    </td>
+  </tr>
+  </table>
+</center>
+
+<br />
+
 <h3>Non-linear fitting</h3>
 In this example, we use Google's <a href="http://code.google.com/p/ceres-solver/">CERES</a> nonlinear fitter to approximate the
 blue metallic paint from the <a href="http://www.merl.com/brdf/">MERL database</a> using a Lafortune lobe (Note that we do not provide the data in ALTA package, you will have to download it). The resulting BRDF is exported in a shader format compatible with BRDF Explorer.
@@ -58,7 +98,7 @@ This command line is rather long. To help you design complex command line in a m
 
 <h3>XML scripts</h3>
 
-Here is the script to perform the same fitting as the previous example. It 
+Here is the script to perform the same fitting as the previous example. It
 performs the fitting of the blue metallic paint from the MERL database using
 a Beckmann lobe (note there is no shadowing term, nor Fresnel term):
 
@@ -78,7 +118,7 @@ a Beckmann lobe (note there is no shadowing term, nor Fresnel term):
 		<function name="nonlinear_function_diffuse" />
 		<function name="nonlinear_function_beckmann">
 		</function>
- 		
+
 		<!-- Define the ftting procedure to use -->
 		<plugin type="fitter" name="nonlinear_fitter_ceres" />
 
@@ -86,7 +126,7 @@ a Beckmann lobe (note there is no shadowing term, nor Fresnel term):
 		<plugin type="data" name="data_merl" />
 
 		<!-- Parameter -->
-		<parameter name="export" value="explorer" /> 
+		<parameter name="export" value="explorer" />
 	</action>
 </alta>
 \endverbatim