Filed under: HDR

HDR Reflectance and realtime bounced lighting

One thing i forgot to post (doh!) while working on the reflection setups in my engine for shadowracer was the reflectance tests i had done. I had typed an incorrect value and ended up with a super low res reflection - This and something Blindside had mentioned to me before about trying that as a trick got me into messing around with ambient color and reflectance under the diffuse layer, based on the realtime environment around the car itself. i attempted to layer the lighting setup in such a way to have a diffuse map + ambient surrounding reflectance + the realtime reflection and it looked really nice - but within certain parameters was not giving what i expected due to the nature of the reflection im using. After a lot of messing around and tweaking i reimplemented the layer for ambient reflectance but pre diffuse texture in the pipeline. This means i ran the low pass reflection on the white/blank slate car instead of the diffuse texture. This gave me even better underlying results for the reflectance and i already had an ambient texture attached to the map (a baked AO map) in the 4th slot. Multiplying adding and trying different combinations gave some cool results, so i tried using the abient map as a falloff of reflectance and fresnel and who knows what else i added for the testing phase, but a lot of really interesting results came about. Below is only one of the stages i had reached and i realised i hadnt shown any of this progress so i figured what the hell. The amount of time its taken to finish this small post in between the rest of the fun things that im working on (work side) and the fact that i had an image set already screencapped means you get one bunch of pictures. Enjoy! [caption id="" align="alignleft" width="840" caption="Reflectance of ambient scene lighting and surrounding objects"]
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[/caption] Some notes : the reflection and base shaders are based on my own work, but the original point i started at was BLindsides great DP realtime reflectance in irrliche engine. All shots realtime, +- 300 fps, 16x16 RTT per pass (2 passes per object) on a ATI thats not immense All images are overly exaggerated to demonstrate the effects here, a low level ambient reflectance works really well with any material, wood, metal, concrete etc etc. More sometime, i think!

Reflections finally

OK so i fixed the wrong orientation in the reflections while i had a spare bit of time. They definitely look a lot better now, theres ONE tiny little thing left to do. Theres seaming from this technique which is normal, but for some reason theres a wrong seam elsewhere. I know where, just will take some more time to fix. For now, some better images :
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Reflections, and some HDR

Thanks to SteelStyle who write a nice HDR Image format loader i was able to throw in a quick HDR lit environment map, which i can test with and adapt easily for use in the game. Some other cool things is i keep going round in circles with the reflection. First its upside down, but the right way round. Then its the right way but horizontally wrong etc. I only tried a couple brute force values but ill fix it whenever i get around to thinking on it again. For now, some more in game eye candy.
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