[sldev] GSoC - mesostructures

[Darien Caldwell]

Ah, now that you point it out, the differences are quite plain. Always
good to have a trained eye.  Thanks for the details, and very nice
work. :)


On 7/12/08, Ravish Mehra <ravish.mehra07 at gmail.com> wrote:
> hello guys,
> my name is Ravish and i am currently implementing this mesostructure
> rendering library under google summer of code.
>
> i know i write long answers :) , so bear with me. regarding the visual
> difference between the three techniques -
> 1)  sphere tracing uses a 3D texture known as distance map for finding the
> ray-mesostructure intersection and the quality achieved by this technique is
> highly dependent on the resolution of this distance map. currently its
> 128x128x32. since its a 3D texture we cannot go to very high resolutions.
> hence the images will be at that resolution and certain aliasing effects are
> visible. i have marked such areas in attached image with yellow circles.
>
> 2) Relief mapping's rendering quality on the other hand, depends more on the
> number of iterations we do ( linear + binary steps ). if we do enough
> iterations, it gives amazing results. as can be seen that the aliasing
> effects present in sphere tracing are not present in relief mapping ( height
> field ). but if we do less number of iterations, we may get certain
> artifacts due to incorrect intersections(see attached figure of relief
> mapping). also since it uses a 2D texture we can go to very high
> resolutions.
>
> 3) Pyramidal displacement mapping also tries to give the same quality as
> relief mapping, but it doesnot require as large number of iterations as
> relief mapping. here also we can go to very high resolutions as we are using
> 2D textures.
>
> even the performance(fps) given by the 3 techiques is hugely different. i
> will soon upload a comparison table for comparing their performances.
>
> ravish
>
>
> On Sat, Jul 12, 2008 at 6:26 AM, Darien Caldwell <darien.caldwell at gmail.com>
> wrote:
>
>> Looking at the original Wiki link, I see there are examples of Relief
>> Mapping, Sphere Tracing, and Pyramidal Mapping.  However looking
>> closely, I can't see any visual differences.  What is the main
>> difference between the 3 styles of mapping?
>>
>> On 7/11/08, Lawson English <lenglish5 at cox.net> wrote:
>> > Karl Stiefvater wrote:
>> >>> Again, I may be missing something - but this is how I originally
>> >>> expected sculpts to work when they were initially described.
>> >>
>> >> heh... i think maybe you have too high of expectations.  :)
>> >>
>> >> this technology is still EXTREMELY young and experimental.  remember
>> >> that when pixar puts this level of detail in a movie - each shot takes
>> >> days of rendering time.  in a realtime engine - these things have
>> >> never before been possible.
>> >>
>> >> but you do raise an interesting idea: perhaps the best way to quickly
>> >> integrate mesostructure technology into our system is via the sculpt
>> >> map - the artist provides a high resolution sculpt map - which still
>> >> creates the standard low resolution mesh - but the details are
>> >> fleshed-out via mesostructures.....
>> >>
>> >> very interesting...
>> >
>> > Of course, sculpt maps only have one collion model right now, anyway.
>> > Torus? Sphere? Can't remember.
>> >
>> > Lawson
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