CMSC 435/634: Introduction to Computer Graphics

Assignment 1
Simple Scene
Due February 14, 2012

Now with color coded updates, new....old.

The assignment

Use Pixie (a free Renderman compliant renderer) to model and render a still life representing your hobby. The scene should occupy a volume realistic to the items included. The items should be realistically proportioned relative to one another and any other context in the scene. At least one of your items should be not based on a sphere, cylinder, or other simple primitive. The items can be made of any material you choose, but should be made of different materials. Make them as realistic as possible. Your scene should be illuminated by specific lights (i.e. don't use a constant surface or ambient light source). Select a viewpoint that shows the scene from an oblique angle (i.e. not aligned with any of the coordinate axes).

Using Pixie

Read some tutorials available on the web on using Renderman and Pixie. You might try fundza (for various renderman topics) and Pixie Wiki (for a information on running the Pixie programs). You may also find chapters 1-3 of The Renderman Companion (in library or my office) and the Renderman Specification (linked off the course web page) to be useful. Pixie runs on a variety of platforms (including PCs running Linux, Windows, Mac OS X). Pixie is currently installed on gl, at /afs/

Your development cycle will go something like this:

source /afs/
       (or pixie-bash for bash users)
    edit hobby.cpp 
    make hobby.tif (here's a sample Makefile)
    display hobby.tif (you must be running in an X-terminal for this to work)
until done


Incremental development will probably result in the most efficient use of your time. For example, first try to get your program to draw a single simple object -- perhaps a surface to rest your items on. Once that's working to your satisfaction, add a simple object (maybe something based on a sphere) on top. Then add some more items (remember to make at least one using something other than a sphere). Now line up a good view and lighting. Once you've got the basic setup, keep refining to make it more realistic until you're satisfied or you run out of time (whichever comes first).

Some debugging tips

  1. If your image is blank, check the camera position and direction. It may be pointing away from your scene.
  2. If some primitives are missing, check their orientation (the order in which you have specified the vertices). Polygons are transparent when viewed from behind.
  3. If some primitives are still missing, check the lighting. Surfaces on which no light falls will be black, just like the default background.
  4. If you're having trouble keeping everything straight, give each item a different color until you've got them behaving properly. Then you can change the colors to whatever you want.


Eighty percent of the grade will be for turning in a working program which meets the minimum specifications (correct objects, view, and lighting). The remaining twenty percent will be for realism and creativity (interesting objects, advanced lighting, textures, etc.).

What to turn in

To turn in this assignment you will need to check in your project files to your class CVS repository. Refer to the class CVS instructions for submission details. An overview:
  1. Use cvs checkout to create your own working directory, cs435work. cs435work will contain subdirectories Proj1, Proj2, Proj3, Proj4, and Proj5, in which you will store your files for each project.
  2. Copy your project files to your Proj1 directory.
  3. Use cvs add to place the files that you need to submit under revision control. This includes the C++ program that generates your image, the image it creates, and the Makefile that controls compilation. When you commit, only files under revision control will be submitted!
  4. Use cvs commit to check in any modified files back into the repository.

Never work directly in the repository. You should never edit or write any files to the directory /afs/, and you should never copy any files from that directory. The files within that directory have names ending in ,v and contain internal CVS metadata.

You may modify the Makefile from the example Makefile, but we must be able to run your submission on the gl systems to grade it. Your comments should include information about which computer platform (HW and OS) you developed your program on. Additional comments may help your grade in cases where your program does not operate entirely correctly (since they can give me insight into what you were trying to do). In any case, your programs are expected to be robust and easy to understand. Your comments MUST include a description of help you received or a statement that no help (beyond the text and course staff) was received. If you do not include a statement about help, your project will be returned ungraded.

Working at home

If possible, don't. We test things out on the university computers and may or may not be able to help you if things don't work right for you at home. If you do work at home, your final submitted version must be able to run on the gl machines and must be electronically submitted there.

If you absolutely must work at home, here are some things you may try:

Image display at home
Instead of "display hobby.tif", copy hobby.tif to your home machine and display it there. TIFF image viewers exist for every platform out there (even windows). If you cannot find a working TIFF viewer, you can convert to another format on the gl machines:
    convert hobby.tif hobby.jpg
will convert from TIFF to JPEG. Convert keys off of the file extension and understands a huge number of image file formats. Two suggestions for free viewers that run on many platforms (including windows and linux) is GIMP (from and ImageMagick display (from GIMP is a full-featured image editor (and a great program) that happens to also be able to read and write many image formats. ImageMagick is a set of simpler tools for image display and conversion (including the convert program mentioned above).

You can download your own copy of Pixie. It seems to install simply and reliably (we've tried on linux and OSX), but we can't help you find problems if it doesn't (since they are likely to be related to your particular OS configuration).

Compile at home
The Makefile we provided may not help you here, except for general guidance. Simple RenderMan C files should be quite portable, but allow some time to back-port before submission if you have any #includes beyond ri.h. You will need to figure out from your RenderMan documentation how to compile a RenderMan C+ program to either produce RIB or render directly.