# Computer Graphics Part 7 (Texture mapping)

 Explain the general need and idea of texture mapping adding details to an object using high resolution polygon meshes is costly and not suitable for real time applicationstexture mapping improves surfaec appearance by mapping images onto the surface principles of texture mapping (4) for each triangle in the model/mesh esatblisha  corresponding regino in the texture imageimage has much higher resolution than meshduring rasterization, color the surface by that of textureUV coordinates: 2D coordinates of texture map List three common texture coordinate mappings orthogonalcylindricalspherical why does this problem occur? Uniform steps on the image plane does not correspond to uniform steps in the original 3D sceneaffine texture mapping does not take into account the depth information about a polygon's vertices How do can you solve the affine texture mapping problem? OR: two triangles per sqaure Why does aliasing happen? Sampling frequency is too low w.r.t the signal frequency (e.g. pixel size is too large ccompared to original scene) state the Nyquist limit Why does stochastic sampling show better results than regular sample patterns? Irregular/stochastic sampling makes high frequencies in the image appear as noise rather than aliaseshumans are more sensitive to aliases than noiseJittering (random sampling with n subregions) Explain the Accumulation Buffer What is a texel? pixel of the texture explain the problem with texture aliasing. How can you fix it? one texel covers more than one pixel in the polygon/surface/object or texture minifaction, too many texels for one pixel solution1 - bilinear interpolation, mapping pixel center to uv coordinates and computing pixel color by interpolating the surrounding texel values solution2 - mipmapping explain the steps of bilinear interpolation with regard to texture antialiasing (3 steps) 1. get pixel centre and map into texture space2. get the texture color at that point and the surrounding texels in barycentric coordinates3. interpolate colors and map onto scene AuthorAnonymous ID217137 Card SetComputer Graphics Part 7 (Texture mapping) DescriptionUniversity of Edinburgh School of Informartics Copmuter Graphics (Level 10) Revision Cards created by Simon M. Updated2013-05-02T01:47:30Z Show Answers