Rasterisation Flashcards
(26 cards)
Rasterisation is the process of…
Converting vector points to raster images.
Rasterisation is the final step of…
The 3D pipeline.
A raster image is…
An image made up of pixels.
A JPEG file is a type of [raster/vector] graphic.
Raster
A BMP file is a type of [raster/vector] graphic.
Raster
A PDF file is a type of [raster/vector] graphic.
Vector
The framebuffer is a…
In-memory representation of the display, essentially a 2D array of pixels
Display devices read out the framebuffer [sequentially/separately].
Sequentially
The challenge of rasterisation lies in…
Putting the complex mathematical objects onto the framebuffer
In modern pipelines, once a geometric object has been rasterised into potential pixels, various attributes such as […] need to be interpolated over the object. (pick 2)
Colour, shading, lighting, illumination
The primary difference between Gouraud and Phong shading is that…
In Gouraud, colours are interpolated across each face, while in Phong, normals are interpolated across each face
Barycentric coordinates provide a way to express any point within a triangle as…
A weighted combination of the triangle’s vertices
When interpolating normal vectors across a surface, since interpolation doesn’t guarantee the production of a unit vector, we need to make sure that we…
Re-normalise the vector
Scanline interpolation is an alternative to barycentric interpolation, which…
Draws a horizontal line through the polygon (the pixel line), and interpolates values along both the line and its intersection points
Polygon filling involves…
Determining which pixels are in a polygon and setting their colours accordingly
The parity approach to determining if a point is inside or outside of a polygon involves…
Drawing a ray from the point to infinity, and if the number of intersections is odd, the point is inside, otherwise it is outside
The winding number approach to determining if a point is inside or outside of a polygon involves…
Walking around the polygon’s boundary and counting how many times we go around the point, if the number is non-zero, the point is inside
In order to fill polygons, one algorithm involves using scanline interpolation, where each row of pixels is a scanline, to…
Find all intersections of the scanline with the polygon edges, sort them by x-coordinate, then fill the segments between intersections
If the scanline intersection is an integer, we…
Fill the leftmost pixel, but leave the rightmost pixel blank
If the scanline intersection is a fraction, we…
Round down if it’s inside the polygon, up otherwise
If the scanline hits a horizontal edge, we…
Ignore the bottom horizontal edges
Line drawing is a part of rasterisation that involves…
Converting a mathematical line (edge) into a set of pixels that best approximate it
Bresenham’s circle algorithm draws circles by…
Choosing pixels whose centers are closest to the true circle
Native (DDA) Line Algorithm is inefficient due to the problem of… (HINT: caused by non-integer values)
Floating-point operations and rounding
