CSCI 420 Computer Graphics Assignment 1: Height Fields
CSCI 420: Homework 1
Height Fields Overview
Height fields may be found in many applications of computer graphics. They are used to represent terrain in video games and simulations, and also often utilized to represent data in three dimensions. This assignment asks you to create a height field based on the data from an image which the user specifies at the command line, and to allow the user to manipulate the height field in three dimensions by rotating, translating, or scaling it. After the completion of your program, you will use it to create an animation.
Motivation
This assignment is intended as a hands-on introduction to OpenGL and programming in three dimensions. The starter code we provide is minimal, giving only the functionality to read and write a JPEG image and handle mouse and keyboard input. You must write the code to create a window, handle camera transformations, perform rendering, and handle any other functionality you may desire. We
use GLUT, please refer to class materials and example codes for basic usages. For more information, we recommend to refer to OpenGL’s official website.
[https://www.opengl.org/] or [http://www.glprogramming.com/red/].
Background
A height field is a visual representation of a function which takes as input a two-dimensional point and returns a scalar value ("height") as output. In other words, a function f takes x and y coordinates and returns a z coordinate.
Rendering a height field over arbitrary coordinates is somewhat tricky--we will simplify the problem
by making our function piece-wise. Visually, the domain of our function is a two-dimensional grid of points, and a height value is defined at each point. We can render this data using only a point at each defined value, or use it to approximate a surface by connecting the points with triangles in 3D.
Your Implementation
You will be using image data from a grayscale JPEG file to create your height field, such that the two dimensions of the grid correspond to the two dimensions of the image and the height value is a function
of the image grayscale level. Since you will be working with grayscale image, the bytes per pixel (i.e. Pic->bpp) is always 1 and you don't have to worry about the case where bpp is 3 (i.e. RGB images) for now.
Starter code for Visual Studio, Linux, and Mac are appended. We provide a pic image library to handle image data structures (read-in, storage, and access, write-out...) . Please see the attachments. For VS2017 we have another image library, please look up the reference under ./Cimg-2.3.5/resources for image processing. If you got errors from CImg load() function, usually you’ll need to install ImageMagick and set the path properly, since CImg requires ImageMagick’s ‘convert’ program.
For Linux users, the pic image library which is used to read/write JPEG images. The makefile of the starter code assumes that the pic library locates one level above (i.e. if the starter code is in /home/tom/code/assign1, then the pic library should be in /home/tom/code/pic). You have to compile the pic library before the starter code. Make sure you have libjpeg before compiling pic.
The libjpeg can be obtained by "sudo apt-get install libjpeg62-dev". Here is a sample sequence of Ubuntu commands that get everything compiled:
> tar -xvf pic.tar.gz
> tar -xvf assign1_starterCode_linux.tar.gz > cd pic
> make
> cd ..
> cd assign1
> make
> ./assign1 spiral.jpg
For Mac OS X, before any coding, you must install command-line utilities (make, gcc, etc.). Also, install XCode from the Mac AppStore, then go to XCode, and use "Preferences/Download" to install the command line tools. The makefile of the starter code assumes that the pic library locates one level above
(i.e. if starter code == /Users/tom/code/assign1, then pic library should be in /Users/tom/code/pic).
Please compile the pic library before compiling the starter code. Here is a sample sequence of commands that get everything compiled:
> unzip pic_MacOS.zip
> unzip assign1_starterCode_macOS.zip > cd pic
> make
> cd ..
> cd assign1
> make
> ./assign1 spiral.jpg
Note: Under Mac OS X, if you get an error like this, you need to install Xquartz: xpic.c:21:47: error: X11/Xlib.h: No such file or directory
xpic.c:22:23: error: X11/Xutil.h: No such file or directory
xpic.c:23:42: error: X11/Xos.h: No such file or directory
Note that the starter code includes an "exit" function call in the middle of the main function. On MS Visual Studio, you will see a console window appear briefly and then close right after that. Regardless of what operating system and platform you use to solve the assignment, you need to remove the exit function call and replacewith proper OpenGL initialization.
Handle at least a 256x256 image for your height field at interactive frame rates (window size of 640x480).
• Be able to render the height field as points, lines ("wireframe for triangles"), and solid triangles.
Bind the functions with keys, and users can switch between the three.
• Render as a perspective view, utilizing GL's depth buffer for hidden surface removal.
• Use input from the mouse to spin the heightfield around using glRotate.
• Use input from the mouse to move the heightfield around using glTranslate.
• Use input from the mouse to change the dimensions of the heightfield using glScale
• Color the vertices using some smooth gradient.
• Be reasonably commented and written in an understandable manner--we will read your code.
• Be submitted along with screenshots that capture your height field for three required examples under ./MoreData: GrandTeton-256.jpg, OhioPyle-256.jpg, SantaMonicaMountains-256.jpg (need to see your whole landscapes). Name your screenshots as “GrandTeton-256-HF.jpg”, “OhioPyle-256-HF.jpg”, “SantaMonicaMountains-256-HF.jpg”
• Be submitted along with an about 20-30 seconds video clip for animation (see below Animation Requirements).
• Be submitted along with a README file documenting your program's features, describing any extra credit you have done, and anything else that you may want to bring to our attention.
(30 points) Animation Requirements:
After finishing your program, you are required to submit a video clip about 20-30 seconds to show the functions you implement, based on the requirements and extra credits. We have provided functionality to output a screenshot, included in the starter code, and assume you are using a window size of 640x480. For animation, compile these screenshots into a video and expect a frame rate of 15 frames per second using [ffmpeg], [QuickTime Pro], or [Windows Movie Maker] or other softwares.
Screen recording softwares, such as OBS, are acceptable to use. Please make your video clean and precisely describe what you want to express. Do not include irrelevant contents in your video. Think of it as an artifact.
There is a large amount of room for creativity in terms of how you choose to show your results in the animation. You can use our provided input images, or modify them with any software you wish, or use your own input images. You can also concatenate multiple small sequences into one to make your results look nicer. You can also add caption to assist watching. You may also use your animation to show off any extra features you chooseimplement. Your animation will receive credit based on its artistic content, whether pretty, funny,just interesting in some manner.
Previous example: https://www.youtube.com/watch?v=nf9dnhcD9ZE. This is just an example and doesn’t mean it’s the best video, and of course, you can present your results in a much different way.
