Glitch Pictures anyone?

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ultimatemau
Posts: 11
Joined: Wed Jan 08, 2014 9:48 am

Re: Glitch Pictures anyone?

Postby ultimatemau » Wed May 17, 2017 2:12 pm

jbikker wrote:Trying to implement 'Irregular grids'. Almost there. :)


Looking good! I might give this a try myself :). Are you looking at: http://www.kalojanov.com/data/irregular_grid.pdf ?

jbikker
Posts: 166
Joined: Mon Nov 28, 2011 8:18 am
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Re: Glitch Pictures anyone?

Postby jbikker » Wed May 17, 2017 2:40 pm

Correct. :)

ziu
Posts: 23
Joined: Sat Aug 17, 2013 8:46 pm

Re: Glitch Pictures anyone?

Postby ziu » Fri May 19, 2017 7:08 pm

ultimatemau wrote:Looking good! I might give this a try myself :). Are you looking at: http://www.kalojanov.com/data/irregular_grid.pdf ?

That is an interesting paper! While it does have some similarities to macro-regions it looks a lot more similar to this old algorithm that dynamically increases and decreases the size of each of the grid's voxels depending on the amount of rays entering it and the amount of primitives to be intersected inside the voxel (i.e. the load). The difference with the irregular grid paper above is there the SAH is pre-computed and the voxels are resized as a pre-processing step instead of being dynamically re-computed during rendering like in the old paper (that I link below):
http://graphicsinterface.org/wp-content ... 1986-9.pdf

It is a shame Nemoto & Omachi's (1986) paper was not linked in that article since it seems a lot more relevant than most of the things it references. There are also more recent references with macro-regions e.g. "Macro 64-regions for uniform grids on GPU" (2014), Eugene M. Taranta II, Sumanta N. Pattanaik. The proximity clouds references are kinda pointless. Although it is also a space skipping technique it's different.

Also: The data structure used in the "GPU Ray Tracing using Irregular Grids" paper (uniform grid/bounding volume hybrid) looks really similar to that proposed in the paper "Adaptive cell division for ray tracing" (1991), B. Pradhan, A. Mukhopadhyay. (see Fig. 3). or "A new algorithm of space tracing using a CSG model" (1987), Kadi Bouatouch, Mohamed Ouali Madani, Thierry Priol, Bruno Arnaldi. (see Figure 4). Link:
https://hal.inria.fr/inria-00075942/document

This data structure is also described in "The EXCELL Method for Efficient Geometric Access to Data" (1982), M. Tamminen. (see Figures 2, 5).


So this paper lacks essential references. Plus it has too many pointless BVH and kd-tree references. This part of the paper, the related work and the references, could use some improvement.

Their grid construction algorithm could also be faster. Looking at their 'emit_new_refs', for example, it uses a per primitive loop to generate the prim and cell ids, which will have poor workload distribution in scenes with dissimilar sized primitives. We solve that in our paper:
https://www.academia.edu/13928983/Effic ... hitectures

It is nice that the article comes with code and the algorithms are interesting (though not completely novel) also the results speak for themselves. The solution also has quite nice rendering performance!

It is nice to see people working on grids. They have been IMHO under explored in the present literature so this paper is very welcome!


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