by Mara Silva


MATH155B - Computer Graphics II
Final Project


The goal of this project was to modify the Ray Tracing software provided by Prof. Samuel Buss to include distributed ray tracing features.

The features I implemented are:

- AntiAliasing
- Depth of Field
- Soft Shadows

Also, take a look at:

- Final results

- My inspiration


1. Aliasing effects

2. Antialiasing applied


Looking at the details on the images 1 and 2 it possible to see the improvement on the image where antialiasing was applied.

Picture 1, where no antialiasing technique was applied, presents "jaggie" line. On the frame of the window some parts were not even drawn. Picture 2 presents smooth line.

Multiple eye-to-pixel rays were used to obtain the antialiasing effect. For each pixel, 16 subpixel positions were randomly chosen to be traced from the eye position.




The depth of field effect was obtained using jittered eye positions.

The images on the side, created during the testing phase of this project, are good examples of focal planes. On picture 3 the focal plane is on the bottle, so everything else looks blurry. On image 4 the focal plane is on the image reflected on the mirror, so the reflect image of the bottle is on focus even though the bottle isn't.

Picture 5 and 6 shows the pool scene with focus on the ball.

On picture 5 the eye position was jittered by a small amount, making everything be out of focus except the ball.

On picture 6 the eye position was jittered by a big amount, making the out of focus objects totally blurry.

3. The focal plane is on the bottle

4. The focal plane is on the image on the mirror

5. Eye position jittered a little

6. Eye position jittered a lot



7. Soft shadows casted on the wall


Sometimes an extended light source is desired instead of a point light source. For extended light sources the shadow cast is not sharp: there is a penumbra area around the full shadow area.

The soft shadows effect was accomplished by casting 16 shadow feelers evenly across the light source area and calculating the fraction of light from that source that was hitting the point.

Picture 7 is a clear example of soft shadows. There shadow casted on the right wall is not sharp. Instead, there is a penumbra.


8. Point light source

Pictures 8 and 9 show the difference of using a point light source and an extended light source.


Look at the shadows of the door frame cast on the ground:


Picture 8 has sharp shadows.


Picture 9 has soft shadows.
For the shadows of the door frame everything has a blurry look, because the frame is thin.
Looking at the shadows cast by the wall the separates the door its possible to see the penumbra area.


9. Extended light source



Below I present two rendering of the scene: the first one is using point light source; the second using extended light source.
Pick your favorite!


Single light source.

For a full screen image, click here.



Extended Light source.

For a full screen image, click here.




I found my inspiration at the pages of the Architectural Digest magazine, July 2002, page 141.

My scene is based on the indoor swimming pool at Lyons Demesne, an 18th-century great house in County Kildare, Ireland.

I choose this scene specially because it has abundance of shadows and reflections, two great features easily obtained by the use of ray tracing.

The other reason was that I think is a beautiful scene!



March 16, 2004