CS 184 - Computer Graphics

Notes
Lecture
Cheat Sheet

Here are Some Pictures

Author:
Terence Tong cs184-gt
Amy Mok cs184-ew

TO READER
We figure that it will make it better for you if we write a html
file. however, if you prefer text file, it is not hard to read this as
a text file either.
Here is a hard copy. If you want a online copy go to
www-inst.eecs.berkeley.edu/~cs184-gt/report/ANSWERS.shtml
Thanks

Question 1 
A description including source code of your procedural model. You
might want to include a diagram (diagram.jpg) if this makes things
easier to explain/understand. Note that this desciption will almost
certainly affect your grade. It is in your best interest to invest
more than a couple minutes making it clear and concise.


We want to make a sea shell like whirl. we test out our thought with
the following matlab code

rate = 0.05;
numPoints = 50;
theta = 0:0.05:numPoints * 0.05;
a = [0.4 0.5 0.625 0.75 0.875 1];
color = ['y', 'm', 'c', 'r', 'g', 'b', 'k'];
for i = 1:length(a)
    x = a(i) * exp(theta) .* cos(5 * theta);
    y = a(i) * exp(theta) .* sin(5 * theta);
    plot(x, y, color(mod(i, length(color))));
    hold on
end
The following show the plot in matlab



you can see we have a different line with a different a. In 3d, we
have different z with a different a.

We did our test code in matlab, but we did teh modeling in TCL.

We called out object "Da Sheeit", because we were really frustrated
with tcl (as we learn it)

The one on the left is the front side of "da shit
In the middle is the back side.
On the right is the our "shit" with "shit" texture.





Rendering 1 
An image called rendering1.jpg in jpeg format of your procedural model
displayed in SLIDE. On Windows NT "control"+"Print Scrn" copies the
active window to the clipboard. You can then open Microsoft Imagining
editor and select new image from selection to make an image file with
your window. Save this as a .jpg with less than 10% compression
(quality factor 90% or greater), as this will make the image
reproduction accurate enough to see clearly. This image should have
all the same light sources that your other rendering has (except the
area light source).



Rendering2 
A rendering of your scene by BMRT or Pixie. This should have the same
light sources as the above image, and should be from a similar (if not
exactly the same) viewpoint. Try to arrange it so that you can see as
many differences as possible between the two images above (but keep
them the same size in pixels, which should happen by default). This
will help with the next part of the assignment. You will need to
convert the output of bmrt (.tif) to a jpeg file, call it
rendering2.jpg (Microsoft Imaging editor will do this, again 10% or
less compression)



Question 2 
List at least 4 differences between the two renderings of your scene
described above. These differences should be due to rendering with
BMRT vs. SLIDE. For each difference, point out where in the image the
difference is shown and briefly what the difference is as well as what
caused it. One example might be something to do with antialiasing. If
you play with the -samples option described above you should be able
to produce nice antialiasing in your output. Again you will be
receiving credit for your answers, so it is worth sitting down for
more than a few minutes to write carefully.

1) In the slide output, you can see more 'texture-er' whereas in bmrt
it is a lot smoother

2) The shading in bmrt is a lot smoother and sharper where as in slide
it seems that the shade is everywhere

3) You can see the edge of the image in slide is 'jagged'. bmrt do a
better job in antialiasing than slide

4) There is more the specular reflection in bmrt. in the middle of the
image, you can see a clear highlight

Rendering 3 
Make a single rendering of your object showing shadows from all of the
following directional, spot, and area light sources at once. You
should be able to distinguish each type of light (you might try some
tricks with this such as adding some extra geometry to your scene or
using slightly different colored lights). Again, convert your .tif
file to a jpeg named rendering3.jpg, using less than 10% compression.



The files are whirl_arealight2.slf and whirl_arealight2.rib


Question 3 
Explain how the number of samples affects renderings with an area
light source. Describe what happens when the number of samples is too
small, and why. You should try to be concise and concentrate on the
best answer. You should definitely consult any references you can
find, including each other!

There are actually not much difference unless you look at it pixel by
pixel. you can see teh shading part is different. the one in with less
sampling points, you can see there are more noise in the region and
the one lwith more sampling points, you can see it is smoother.

here are some bitmaps. Jpeg is too low quality to show the differences 

rendering3lessPoints.bmp is one that render our object with 1 sampling
point
rendering3morePoints.bmp is one that render our object with 10000
sampling point.
if you pay very very care attention, you can see there is slight
difference in on the shaded edge of our object. It is more 'pixelly' in the
case of one with less points

It is not that obvious on our object, take a look at
torus_sampling.bmp. There are slighly more different than our object


Renderings 4 and 5 
For the last renderings place your procedural model (or models) inside
a room (you might think of it as an inside out box) with light grey
walls and a texture mapped wood floor (DO NOT use the wood texture
from our example, find your own!). The objective is to make something
like a scene in a museum. One idea I thought would be cool is instead
of having the area light sources on the ceiling as in my example,
recess them up some as if they were skylights. There are lots of other
interesting things you could do... Texture map the walls, make texture
mapped scenes out windows. Place area light sources on the walls
and/or ceiling to illuminate the scene. Then render without radiosity
and with radiosity. Your rendering should display color bleeding, and
other radiosity effects (you can read about these in your
textbook). Again, convert both output files to .jpg format. Name the
one without radiosity rendering4.jpg and the one with radiosity
rendering5.jpg


The one in the left in rendered with bmrt without radiosity
The one in the right in rendered with bmrt with radiosity

The files are whirl_room.slf and whirl_room.rib



Question 4 
Write a short description of the radiosity effects, how are they
different from just using area light sources in the same scene.

Make sure at least one renderable .rib file of your procedural model
(pick one without radiosity) is in the directory. Also, include at
least one .slf file. Pick appropriate file names.


There are BIG difference between the two. One main difference is the
brighness. notice the ceiling, the wall around the arealight. it is
light up! More 'boucing around' light are considered. It also take a
lot longer too!!!