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how can i reflect the sky


matt_vinoir
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with exterior scenes. the background image alone won't reflect in glass. I heard about skydomes but don'r know what they are. I put a massive spher over the model and flipped the normals. I had to not use radiosity on the sphere as it crahed but imagine is blechs it out too. It sort of works. THe sky is very dark though. I use self illuminate but i feel i'm going aboutthisin a funny way. Whats the best and simplist way to do this?

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i've got the same problem. i'm using the IES system to light my exterior. the image is an interior room looking out.

 

do i use the skydome as my skylight?

 

how do i light the skydome to reflect back

at the model?

 

if the skydome is my skylight, do i need to turn off the skylight in the IES system?

 

advice is appreciated

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not using viz 4 for radiosity, i wonder if it's similar to the method used in Cinema4D?

 

i use a skyobject or skydome with a nice strong sky map on it and make it not visible to the camera. in this state it doesn't render because it's invisible to the camera, but it does still effect the radiosity, so image based lighting from it can be used. i then just use a normal environmental image for the backround which doesn't effect radiosity.

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VIZ4 uses the diffuse color for the reflectance of a material. Usually for clear glass the diffuse, ambient, reflect color swatches are set to black. Black is transparent... Adjust the reflect color swatch until you get the right reflection of the environment map.

 

Chico

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Hi all,

 

To be honest I'm more a max3.1-man than viz4-oriented, because I could not get exteriors right in viz. Interiors are fine, but exteriors are hell: the sky always seems blown out, my multiple skydomes just don't seem to work. The results are catastrophical and don't seem logically at all...

 

So my only tip is not to use viz4 for exteriors...

 

rgds

 

nisus

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  • 2 weeks later...

Matt,

 

I am in the process of doing a side-job in VIZ 4, and after seeing your post I decided it was time for me to get a skydome nailed down. I have one placed and it seems to work well. It is my first truly sucessful attempt (that wasn't by accident)

 

The skydome does need to be lit by its own exclusive omni. Simply exclude all other objects from the light source to not invade your scene.

 

And dont worry about having to turn off radiosity for the dome because it is required. ...unless of course you want the entire scene washed over with blue from the sky. Turn off radiosity for the grass as well or it will do the same.

 

Let me know if it helps - and if you have another question.

 

Good luck,

Spongebob

Detroit, MI

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hi matt

 

i guess you've already done that, but if you didn't - after processing radiosity in VIZ4 you must adjust the environment setup correctly : a quick rule of the thumb is to check in daylight and exterior, AND set Physical Scale to the value of your strongest light.

 

Physical scale is used for all reflection/ refraction calculations (and the calc of the non-physical lights), so it needs to be set up correctly - for instance, for bright sunlight it could go up to 80,000lx (as bright as the sun).

 

If it still doesn't show (and it should have been), either try to light up the skydome only, OR use diffuse map in self-illumination spot.

Also, I guess you wouldn't need to use the skydome, as it should also reflect the background image (please make sure you've checked "Process Background and Environment Maps" also).

 

Good luck ;)

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Thanks for your help guys, it was the physical scale, just had to wack it really high to match the daylight.

 

Spongebob, one question about the skydome, can you get a skydome of part sky part land? My vr's are an obvious example of where a standard bitmap doen't work too well, thanks

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