Advanced Computer Graphics
• Assignment 3 - Lightfield Viewer

Due: April 10

Code

• I used the starter code from assignment 2 to build the viewer. At initialization two framebuffers and two renderbuffers are allocated for the algorithm. At each frame, the uv plane is rendered to one of the renderbuffers and the st plane to the other. These renderbuffers are read down to memory and combined. The values in memory are now a set of 4D values indicating the intersections of the camera rays and the two planes. These values are passed to a LightSlab class that samples the lightfield depending on the interpolation scheme desired. These sampled values are aggregated and then drawn to the screen via glDrawPixels(). Here is a picture of the working system:

2. Interpolation and Mulitple Slabs

• I chose to implement the interpolation of the lightfield as my first extension. I modified the LightSlab sample method to allow bilinear interpolation in uv and st and quadralinear interpolation in uvst. The results are shown below:



No Interpolation




Bilinear Interpolation in UV plane




Bilinear Interpolation in ST plane




Quadralinear Interpolation in UVST hypercube



• Notice that the spatial resolution improves if I interpolate in ST, but the reflections on the model are still aliased. If I interpolate in UV I get better resolution of the model, but the reflections are disjoint. The quadralinear interpolation combines the two methods to produce the best pictures.
• The next extension I made was to allow multiple slab lightfields. To do this, I simply load in multiple light slab files, draw the appropriate uv and st planes, extract the relative samples, and aggregate the results. Here is a set of images that shows the multiple slab implementation:

• Some useful controls are:
  • 'f' changes to lightfield mode to render the lightfield at the current location... the camera can still be moved although it can be slow and so you can switch back to polygon mode for ease
  • 'e' allows you to explore the images that comprise the lightfield
  • 'x' will allow you to switch between exploring the (s,t) and (u,v) planes in the explore mode
  • 'w', 'a', 's', 'd' are the up, left, down, right controls to adjust the explored (s,t) plane
  • 'u', 'h', 'j', 'k' are the up, left, down, right controls to adjust the explored (u,v) plane
  • 'l' switches the interpolation (lerp) mode... default is uv bilerp, then st bilerp, then uvst quadlerp, then no lerp
  • 'q' quits
  • 'z' saves a png image called image.png, but it is upside down and clipped... didn't have enough motivation to attempt to fix this