Subsampling, anyone?

Posted on:September 29 2006

Yesterday evening I sat down for some minutes and improved the lightmap generator of irrEdit with subSampling. That's just a bit like the technique known as AntiAliasing. This is the result:
The lightmap texture on both pictures has the same size (256x256, for the whole level, not per face). On the right pictures I'm calculating 4 samples, on the left only one. The speed decrease is not 4 times as expected, but a lot less, I guess because of caching, nice. I added the option to choose between 1, 4, 9, 16 and 25 samples per texel. Will be in the next release.





Comments:


great !
hujan
Quote
2006-09-29 17:11:00


Why not apply a gaussian blur on the final texture?
Lonerunner
Quote
2006-09-29 17:32:00


@Lonerunner: because that would cause bleeding between sub-areas of the lightmap texture. Remember a lightmap is an atlas texture, with lots of non-continuous regions packed near to each other, a context-less gaussian blur would cause horrible errors.

@niko: Nice improvement :) I'm curious, hope you don't mind answering questions:

1) what kind of spatial arrangement did you use for your 4 taps? Regular grid or jittered?

2) I assume you're using texture gamma ramping to blow out the areas close to the lights (rather than HDR)?

Once you add some element of or approximation of global illumination it will look much better - perhaps just a secondary light bounce or an ambient occlusion pass. That way you won't need as many lights to avoid the typical over-dark areas caused by direct-only lighting.
steve
Quote
2006-09-29 18:04:00


2 *niko* : and what about releasing terrain scene node in irrEdit ? It would be the best improvement :)
Bazzilic
Quote
2006-09-29 19:46:00


@steve

ambient occlusion - oauuuu that is simple and soo COOL!
(maybe niko can play with that)
Lonerunner
Quote
2006-09-29 19:53:00


Can't wait to see it in action.
Polrod
Quote
2006-09-29 23:29:00


That's a very nice feature!
cmoibenlepro
Quote
2006-09-29 23:48:00


Very nice features! It would be very nice too to see also global illumination, and also other types of lights like "area" lights and sunlight.
Bulbazaur
Quote
2006-09-30 05:55:00


they are planned already. :) Spacial arrangement: Just an orthogonal grid, of 1², 2², 3², 4² or 5² points. And currently I'm not using any gamma ramping, just stupid clamping. But that's something I'd like to change as well soon.
Nice idea, I didn't think about doing skylight calculations in there at all yet. :)
niko
Quote
2006-09-30 07:38:00


sooo coool niko...totally loving irrlicht and irredit more and more..!
tunde
Quote
2006-09-30 20:43:00


This is really beautiful. The only thing more I could ask for in a lightmapper is radiosity, but I guess I should just write my own.
anonymous
Quote
2006-10-18 04:50:00


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