geometric modelling Flashcards
(30 cards)
What is WebGL?
A JavaScript API for rendering 3D graphics in web browsers, based on OpenGL ES.
What is OpenGL?
A cross-platform graphics API for rendering 2D and 3D vector graphics.
What is Three.js used for?
To simplify WebGL development by providing a higher-level interface to build 3D scenes.
What are the core components of a Three.js scene?
Scene, camera, renderer, geometry, material, mesh, and animation loop.
What geometric primitives are available in WebGL?
GL_POINTS, GL_LINES, GL_TRIANGLES, GL_TRIANGLE_STRIP, etc.
What is a triangle mesh?
A collection of triangles defined by vertices that together form a 3D surface.
Why are triangle meshes commonly used?
They are simple, efficient, and well-supported by hardware for rendering.
What is the PLY file format used for?
Storing 3D data including vertices and face definitions, often from scanned models.
How are triangles defined in PLY?
Each face is listed with indices referencing three vertices.
What is the OBJ file format used for?
A simple 3D geometry definition format using vertices and face indices.
How does OBJ indexing differ from PLY?
OBJ starts indexing at 1; PLY starts at 0.
What is the Face-Vertex mesh structure?
A basic structure with a list of faces and vertices; easy for rendering but poor for editing.
What is the Face-Edge-Vertex structure?
A full mesh representation where each element links to adjacent faces, edges, and vertices.
What is a disadvantage of Face-Edge-Vertex structure?
It consumes more memory and can be complex to manage.
Why is local adjacency important in mesh structures?
To support operations like editing, simulation, and mesh traversal efficiently.
What is the purpose of 3D scanning?
To capture the geometry of real-world objects and convert it into digital mesh form.
Name devices used for 3D scanning.
Kinect, iPhone FaceID, LiDAR sensors, Structure Sensor.
What is the Phong lighting model?
A lighting model with ambient, diffuse, and specular components for simulating realistic shading.
What is ambient light in the Phong model?
A base light that simulates indirect environmental illumination.
What is diffuse reflection in the Phong model?
Light that reflects evenly from a surface depending on angle to light source.
What is specular reflection in the Phong model?
Bright highlights caused by reflections visible to the viewer, sharpest on smooth surfaces.
What does the Phong model not account for?
Inter-reflections, shadows, or global illumination.
What is ray tracing?
A rendering technique that simulates light paths for realistic effects like reflection, shadows, and refraction.
What is the downside of ray tracing?
It is computationally expensive and slower than rasterization.
