GTT Tools, Their Features, And The Concepts They Help Teach

GTT tools, their features, and the concepts they help teach

Raster Module Selected relevant applications of raster graphics: Photography, Graphic Design, Web Design, Illustration, Digital Video, Medical Imaging, Fine Art, Media Studies

Tools and their Concepts To Teach Features Basic Pixel-setting Tool  All operations in a raster graphics program serve to alter pixel values.  Different “tools” in standard programs are really just different variations on simple pixel-setting/creating. (Using this tool you can make a “paintbrush,” “eraser,” “airbrush,” and more.)  The tools defined in raster graphics packages are based on decisions made by the applications designers/programmers and do not represent the way things have to be. (Using the GTT, students can make a wide variety of pixel-creation tools that have a look-and-feel quite different from those found in programs like Photoshop and Painter.) Mask size The size of the brush is defined by its height and width in pixels. Brush shape Brushes do not have to be round or square. You can define a brushes shape to be anything you like. Actual-size and 400% To design with individual image pixels, it helps to have a magnified view that present a preview single image pixel over many screen pixels. Paint and Numeric Numeric modes show how the computer represents the data being entered. Paint mode Entry modes helps make that data entry more enjoyable and productive for most human users. Alpha values When pixel colors are re-set, the new information can contain not only new colors, but also weighted contributions from different parts of the brush. (the brush mask permits varying levels of transparency, or alpha value.) Color Choice of color combined with alpha values to define “brush-like” pixel-changing tools. Composition methods In the physical world colors mix according to the properties of their media and (currently Over, pigmentation and the substrate and mixing method. On the computer, all mixing must Erase, and Under) be algorithmically defined. There is no “natural” way of mixing. Some methods mimic traditional materials mixing, and other are possible only on the computer. Choice of presets (currently Clear, Circle, Rectangle, Drop Shadow, and Airbrush) Explanatory text Introduces and reinforces the pixel-setting concepts above. Includes definition of “pixel.”

Filter Tool  All operations in a raster graphics program serve to alter pixel values.  Different “filters” in standard programs are really just different variations on simple pixel-processing algorithms. (Using this tool you can “blur,” “sharpen,” “find edge,” and more.)  The filters offered in raster graphics packages are based on decisions made by the applications designers/programmers and do not represent the way things have to be. (Using the GTT, students can make a wide variety of filters that have a look-and-feel different from those found in programs like Photoshop and Painter.) Filter kernel size The footprint of the filter kernel influences how “strong” a filter one can design (e.g., on e that blurs an image beyond recognition) and what type of effects are possible (subtle blurring is not possible with too small a filter kernel) Filter shape Different relative dimensions of the kernel produce different filtering effects. Actual-size and 400% To design with individual image pixels, it helps to have a magnified view that present a preview single image pixel over many screen pixels. Paint and Numeric Numeric modes show how the computer represents the data being entered. Paint mode Entry modes helps make that data entry more enjoyable and productive for most human users. Kernel weights Like alpha values, the different kernel weights determine to what extent the affected image areas will be altered. Choice of presets (currently Clear, Sharpen, Blur) Explanatory text Introduces and reinforces the filtering concepts above. Includes explanation of filtering. Mask size

Selection Tool  The area that will be acted upon by tools like the filter tool is determined before the action by selecting an area of the image.  The filters offered in raster graphics packages are based on decisions made by the applications designers/programmers and do not represent the way things have to be. (The GTT offers some different options to make this point clearer.) Rectangle Circular/Oval Freeform Paint-Out Demonstrates that selection can be creative too by offering an unusual selection tool not found in standard applications. De-Select

Inspection Tool All raster images are represented by arrays of pixels. An image on the computer screen is the visualization of data stored within the computer. To change the image, one must change the underlying data. The ways in which the data can be visualized and changed are determined by the type of data representation used.

View and edit raster data Each pixel is a location in the array that has associated with it Red, Green, Blue, and (R,G,B, and Alpha) Alpha values. 2D Geometric Module Selected relevant applications of 2D geometric graphics: Illustration, Graphic Design, Engineering, CAD/CAM, Fine Art, Web Design, Publishing Tools and their Concepts To Teach Features

Primitives Tool 2D primitives, 2D matrix transformations for rotation, scaling, and translation, layers in 2D draw-type programs, fills and outlines, patterns, and some concepts in typography. Create rectangle Create circle/oval Create triangle Scale (using handles) Rotate (using handles) Translate (click and drag)

Inspection Tool All 2D geometric forms are represented by mathematical descriptions of lines and An image on the computer curves and shapes. These forms can be operated upon mathematically to make screen is the visualization of them move (translate), get bigger and smaller (scale), and turn (rotate). data stored within the computer. To change the image, one must change the underlying data. The ways in which the data can be visualized and changed are determined by the type of data representation used.

3D Geometric Module Selected relevant applications of 3D geometric graphics: Films, animation, games, engineering, architecture, medicine, graphic design, illustration, industrial design, fine art.

Tools and their Concepts To Teach Features

Primitives Tool  Many complex forms can be created by combining simple 3D “primitives” such as the sphere, cuboid, and cylindrical ones offered here.  Primitives are also used to introduce basic 3D concepts such as the x,y, and z axes, and simple lighting and shading (also see Light Tool). Create cube Create sphere Create cylinder

Light Tool  Objects have no visible “color” until some kind of lighting is defined.  The final “color” of the object is a combination of the objects material color and the lights shone on it (as well as other material properties). Light color Light direction  The current lights are directional only. Changing the direction can invoke (numerical and slider different times of day and reveal different aspects of a scene. input)  Use of multiple lights and directions are usually necessary to properly light a scene.  Camera Tool  The effect of a scene can be manipulated by changing the camera position and other parameters.  The “virtual” camera used to visualize the underlying 3D data has many of the same “controls” as a real camera, for example, position, direction, rotation, and field of view. Pan and Zoom Rotate

Inspection Tool  The position, orientation, and scale of objects and groups of objects in a 3D An image on the computer scene are stored in a data structure called a scene graph. screen is the visualization  Using the Inspection Tool in the 3D Geometry Module, users can explore of data stored within the this conceptual framework with either numerical and slider based input. Users computer. To change the see a representation of each matrix as well as a diagrammatic view of the image, one must change graph structure. the underlying data. The  The concept and use of nodes and group nodes is explained and made ways in which the data can accessible with a GUI drag-and-drop interface. A transformation applied to a be visualized and changed group node acts on all the objects in the group. are determined by the type  The ordering of transformations matters. of data representation used. Matrix Workspace Add, edit, re-arrange and remove translation, rotation, and scaling matrices Create Group Nodes Work with scene graph

The same in all modules

Tools and their Concepts To Teach Features

Layer Tool Different types of data representation result in qualitatively different types of View and change layer order images, each with its pros and cons. Users must learn when to use which type of representation (usually by decided what piece of software to use).