Lecture 7: Intro to Geometry, Splines, and Bezier Curves (11)

akhilvemuri

I also often see both point clouds and polygon meshes used in combination with other tools and techniques, such as rigging, shading, and lighting, to create the final images and animations that are in movies and games. In fact, it seems that even mapping and texturing require the use of 3D geometry. Though subtle, I believe that these representations can be used all throughout common graphics techniques, besides just simulation and animation.

mooreyeel

In 2D you can represent any polygon as a mesh of triangles. Is here an issue with that in 3D? is it more complicated, or is it something like convert each polygon on the surface to a triangle and then like integrate it to get the solid shape or something.

joeyzhao123

I thought that most modern graphics with 3d models used triangles still on the mesh, particularly in games. There is an interesting explanation of it here. https://stackoverflow.com/questions/6100528/why-do-3d-engines-primarily-use-triangles-to-draw-surfaces#:~:text=It%20takes%20a%20lot%20of,every%20frame%20that%20gets%20rendered.

JustinHuey1

I know that in lecture we talked about why we use triangles to create polygon meshes. If we were trying to represent shapes that were created from these other polygons like the circles and cubes here, would it still be better to use triangles to create them or just by their shape be better?

Staffjamesfong1

@JustinHuey1 That's a good question. Other polygons are possible, but triangles are typically the best for fast rendering because there are fewer edge-cases (literally) for the code to deal with. For example, the points of a triangle will always be on the same plane, so it is clear how to fill in the points within the triangle in 3D space. The same is not true for the other polygons!

I also often see both point clouds and polygon meshes used in combination with other tools and techniques, such as rigging, shading, and lighting, to create the final images and animations that are in movies and games. In fact, it seems that even mapping and texturing require the use of 3D geometry. Though subtle, I believe that these representations can be used all throughout common graphics techniques, besides just simulation and animation.

In 2D you can represent any polygon as a mesh of triangles. Is here an issue with that in 3D? is it more complicated, or is it something like convert each polygon on the surface to a triangle and then like integrate it to get the solid shape or something.

I thought that most modern graphics with 3d models used triangles still on the mesh, particularly in games. There is an interesting explanation of it here. https://stackoverflow.com/questions/6100528/why-do-3d-engines-primarily-use-triangles-to-draw-surfaces#:~:text=It%20takes%20a%20lot%20of,every%20frame%20that%20gets%20rendered.

I know that in lecture we talked about why we use triangles to create polygon meshes. If we were trying to represent shapes that were created from these other polygons like the circles and cubes here, would it still be better to use triangles to create them or just by their shape be better?

@JustinHuey1 That's a good question. Other polygons are possible, but triangles are typically the best for fast rendering because there are fewer edge-cases (literally) for the code to deal with. For example, the points of a triangle will always be on the same plane, so it is clear how to fill in the points within the triangle in 3D space. The same is not true for the other polygons!