help on fresnel effect on glass

[jdomingo]

hi gurus

i noticed that my glass (see image please) has no fresnel effect, i am using the fast fresnel shader and the standard glass material on LW surface preset, any advice on how can i achieve this effect? thanks in advance

[silverlw]

Fresnel fx can be done with gradients, check the attached surface for good chrystal glas.
Br JS

[jure]

hi gurus

i noticed that my glass (see image please) has no fresnel effect, i am using the fast fresnel shader and the standard glass material on LW surface preset, any advice on how can i achieve this effect? thanks in advance

I belive fast fresnel is a shader right? Unfortunately shaders cannot be rendered with Kray. Use Fresnel in nodes instead it's more powerful too...

[jdomingo]

thanks for the SRF silverw, mmm i thought when using nodes with physky i wont get contact shadow or is it just for delta node? but will try it..thanks

[silverlw]

If you do a search on "contact shadows" in this forum you will get several pages where it is discussed and further explained.
I hope that helps. If you still cant get a hang of it, upload a simple scene where you have these problems so we can point out how to improve it.
/Silverlw

[jdomingo]

here is another one that frustrates me. im on texturing stage now and my test render is sooooooo slow for a test, please see image.
35 minute is too slow for me. i am guessing it's my reflective and transparent materials. before that i have not assign transparency and reflection yet and my test render is fast. any advice or tip about reflectivity and transparent materials? thanks

[jdomingo]

because of too much frustration i forgot to attached the image and settings. here you go

[silverlw]

For testrenders i think you have quite high settings.
Choose "General/render preset/Low for a start. Also turn off Antialiasing or atleast dont use fullscreen AA for tests.
Under finalgather tab, choose Minrays/maxrays 50/250.
What cpu are you using?

[jdomingo]

i have dell precision T7400, zeon e5420 2.5ghz, 4gb ram, quadro fx1700, 64bit windows xp.
if i use low setting for testing how can i gauge the setting for my final image? for sure i cant use the low setting if i want to render for final one, that is why i am using a little high setting even for my test. and these things the client doesnt understand. i show them a low setting with low AA, oh my, i heard so many unneccesary comments.
thanks for your reply

[jure]

here is another one that frustrates me. im on texturing stage now and my test render is sooooooo slow for a test, please see image.
35 minute is too slow for me. i am guessing it's my reflective and transparent materials. before that i have not assign transparency and reflection yet and my test render is fast. any advice or tip about reflectivity and transparent materials? thanks

Can you show your transparent/reflective surface settings? the render time is indeed unusually slow. I use fresnel node for my glass surfaces and it works fast and looks fine... I can send preset tomorrow if you want.

[jdomingo]

hi jure, thanks.
here is my glass setting, purely from LW surface preset. please tell me if i am right on this. if i am doing a low setting on test render, i wont get same result when i increase to higher resolution for final render using low setting right? i am thinking since its a low resolution example 800x600 or 640x480 even with a kray high setting will render fast. only when i make high res render then it will render slow. i dont know if i confuse you, pleaes enlighten me. thanks to both of you

[jure]

hi jure, thanks.
here is my glass setting, purely from LW surface preset.

This preset is no good. Maybe it looks good in some scenarios but it has no fresnel properties and why the heck is translucency used? Glass has transparency, reflection and refrection properties which are linked together with Fresnel equation. When using Kray you would generally want to mimic this physical properties of materials to obtain most realistic results.

I'm attaching my basic window glass preset. Try it and tell me if it works better for you.

please tell me if i am right on this. if i am doing a low setting on test render, i wont get same result when i increase to higher resolution for final render using low setting right? i am thinking since its a low resolution example 800x600 or 640x480 even with a kray high setting will render fast. only when i make high res render then it will render slow. i dont know if i confuse you, pleaes enlighten me. thanks to both of you

Yes that is true. The rendertime depends on the size of the final render and on the render settings. Use medium settings for start and change FG and AA settings for final/test renders.
For test I suggest FG min rays 100 max 400, pass 1 - other settings leave at default. Sampling tab Grid 2-3 FSAA ...
For final I suggest FG min rays 100 max 800, pass 2 - other settings leave at default. Sampling tab Grid 5-6 FSAA ...

[jdomingo]

thanks Jure, oh men arent you supposed to be having a holiday now? Jure where did you send your preset? thanks again.

happy holiday and more power to all involved in kray

[jure]

thanks Jure, oh men arent you supposed to be having a holiday now? Jure where did you send your preset? thanks again.

happy holiday and more power to all involved in kray

Ah sorry forgot to attach the preset. Here it is.

[silverlw]

Hi Jdomingo,
Also turn off doublesided property of the glass. If you use Jures glass preset im pretty sure you see a speed improvement.
Tell us how it goes.