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Nuno Silva committed 3c83ab2

minor changes to the figures layput

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 \np A lot of work has been done in order to achieve better results with a lower computational time in illumination, although these are focused on individual lights. In order to deal with a larger amount of lights some techniques where developed.\\
 
 %resumo do WARD, G. 1994. Adaptive shadow testing for ray tracing. In Photorealis- tic Rendering in Computer Graphics (Proceedings of the Second Euro- graphics Workshop on Rendering), Springer-Verlag, New York, 11–20.
-Ward \cite{WardG94} presented an approach which trades accuracy (as opposed to storage) for speed. This method provides an increase of speed ranging from 20\% to 80\%. He also allows the user to control the reliability and the accuracy. This method is not based in testing sources for probability of visibility, but instead uses the probability of untested sources to estimate a contribution, thus allowing for smooth shading and no apparent compromise in accuracy.\\
-When testing, Ward realized that the more lights in a scene, the more the algorithm improves. This is because of more important lights being tested first, and less important being tested only if their visibility is considered important for the calculation.\\
+Ward \cite{WardG94} presented an approach which trades accuracy (as opposed to storage) for speed. This method provides an increase of speed ranging from 20\% to 80\%. He also allows the user to control the reliability and accuracy of the technique.% REVER MELHOR PARA FAZER + SENTIDO
+This method is not based in testing sources for probability of visibility, but instead uses the probability of untested sources to estimate a contribution, thus allowing for smooth shading and no apparent compromise in accuracy.\\
+When testing, Ward realized that the more lights there are in a scene, the more efficient the algorithm becomes. This is because of more important lights being tested first, and less important being tested only if their visibility is considered important for the calculation.\\
 Ward's algorithm avoids stochastic sampling, therefore reducing noise, in order to create a more pleasing and fast result.\\
 
 %Este paper ta na pasta de downloads.
 
 The implementation supports three types of point lights: omni, oriented, and directional, each having its own light tree. Ideally the light tree would group the point lights that have similar orientation and spacial proximity in order to improve the groups quality. The cluster error bounds (difference between the exact and approximate representations) is calculated by multiplying the upper bounds on the material, geometric and visibility terms. \\
 
+
 The reconstruction cuts technique attempts to further reduce computational costs when going down the light tree (to reduce the amount of error). Given a set of nearby samples (locations where lightcuts have already been calculated), if all of them agree that a node is occluded, it is discarded. If a node's illumination is very similar across those samples, then that node is cheaply interpolated using impostor lights. Otherwise the normal lightcuts algorithm goes on. There are a few exceptions, for example no interpolation is allowed inside glossy highlights as it could lead to visible artifacts. Interpolating or discarding nodes, especially if high up in the tree, provides great cost savings. By exploiting spatial coherence, reconstruction cuts can shade points using far fewer shadow rays than lightcuts, this allows the generation of much higher quality images, with anti-aliasing, at a much lower cost than with lightcuts alone. \\
 
 
 
 
 
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+%%%%%%%%%%%%%%%%%%%%%%%%%%
+\section{Metric Systems}
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 %%%%%%%%%%%%%%%%%%%%%%%%%%
 \section{Lightcut Results}
 %%%%%%%%%%%%%%%%%%%%%%%%%%
 \np
 The lightcuts implementation was tested in 5 scenes. All results use a 2\% error threshold and a maximum cut size of 1000 nodes. All images in this section have a resolution of 640x480 with one eye ray per pixel. \\
 
-\begin{figure}[h]
-	\centering
-		\includegraphics[width=0.50\textwidth]{kitchen.PNG}
-	\parbox{0.70\textwidth}{\caption{Kitchen scene with direct light from 72 area sources. }}
-	\label{fig:kitchen}
-\end{figure}
-
 In all tests there are no visual differences compared to the tests considering all lights (no clustering). The first scene (figure \ref{fig:kitchen}) contain several area lights that are approximated by a few point lights, in the second (figure \ref{fig:tableu_hdr}), the HDR environment map is approximated by a few thousand directional lights. The other scenes mix illumination sources and have a more complex geometry, the reconstruction cuts technique was used to reduce the aliasing without increasing the computation time too much. Reconstruction cuts allows to generate higher quality images, with anti-aliasing, at much lower cost than with lightcuts alone.  \\
 
-\begin{figure}[h]
-	\centering
-		\includegraphics[width=0.50\textwidth]{tableu_hdr.PNG}
-	\parbox{0.70\textwidth}{\caption{Tableau scene illuminated by an HDR environment map. In parentheses are averages over only pixels containing geometry.}}
-	\label{fig:tableu_hdr}
+
+\begin{figure}[ht]
+ \begin{minipage}[b]{0.5\linewidth}
+ \centering
+ \includegraphics[scale=0.8]{kitchen.PNG}
+ \parbox{0.9\textwidth}{\caption{Kitchen scene with direct light from 72 area sources. }}
+ \label{fig:kitchen}
+ \end{minipage}
+ \hspace{0.1cm}
+ \begin{minipage}[b]{0.5\linewidth}
+ \centering
+ \includegraphics[scale=0.8]{tableu_hdr.PNG}
+ \parbox{0.9\textwidth}{\caption{Tableau scene illuminated by an HDR environment map. In parentheses are averages over only pixels containing geometry.}}
+ \label{fig:tableu_hdr}
+ \end{minipage}
 \end{figure}
 
 
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%
-\begin{thebibliography}{}
+%\begin{thebibliography}{}
+%\bibliography{mybib}
+%\bibliographystyle{plain}
+%\end{thebibliography} 
+
+\bibliographystyle{abbrv}
 \bibliography{mybib}
-\bibliographystyle{plain}
-\end{thebibliography} 
-
-
 
 \end{document}

mybib

-@conference{WardG94,
-	Author = {Gregory J. Ward},
-	Booktitle = {Proceedings of the Second Eurographics Workshop on Rendering},
-	Date-Added = {2011-05-12 13:20:32 +0100},
-	Date-Modified = {2011-05-12 13:25:02 +0100},
-	Journal = {Photorealistic Rendering in Computer Graphics (Proceedings of the Second Eurographics Workshop on Rendering)},
-	Read = {1},
-	Title = {Adaptative Shadow Testing For Ray Tracing},
-	Year = {1994}}
+@conference{WardG94,
+	Author = {Gregory J. Ward},
+	Booktitle = {Proceedings of the Second Eurographics Workshop on Rendering},
+	Date-Added = {2011-05-12 13:20:32 +0100},
+	Date-Modified = {2011-05-12 13:25:02 +0100},
+	Journal = {Photorealistic Rendering in Computer Graphics (Proceedings of the Second Eurographics Workshop on Rendering)},
+	Read = {1},
+	Title = {Adaptative Shadow Testing For Ray Tracing},
+	Year = {1994}}
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