Further explanation using radiosity

[G]

I read up on radiosity last night. in the viz4 book it made referrence to units scale. i use millimeteres in autocad, then in viz i have units set to millimeters too, will these units affect settings in radiosity dialogue box and ifso, what settings should be used in relation to millimeters. Any other tips you can give me on settings would be great. at the moment, if i use standard lights and no radiosity, the rendering looks fine, as soon as i use radiosity, the decals on the signage and the blue plastic panels gets washed out?

 

Thanksyou for your help and patients,

 

G

[ZepSOFD]

G,

 

As long as the units match from acad to viz/max and the right lighting standard is used(international, american) there really should not be any problems. If you mismatch the units and/or the lighting standard the radiosity engine will not be able to produce the proper results.

 

If you have materials that are washed out(assuming the light intensities are appropriate for the scene) try checking the exposure control to see if the brightness or contrast are set to high(these values vary depending on your scene). If lowering the brightness/contrast isn't enough, in your material, lower the RGB Level in the Output section of the bitmap, start with half and see how that goes. If you have materials that are based on diffuse color you may have to darken up the diffuse to acheive what you would deem as the appropriate color when rendered. Don't worry if the preview or your material looks dark in the material editor this is normal, radiosity is not taken into account when the preview is generated.

 

Use logarithmic for the exposure control, In my opinion it is as manual and simple as you can get, meaning if you change views or your camera changes position you won't receive unexpected results because of some interpretive value that you have no control where the samples are taken. If you change it, it will remain the same until you change it again.

 

Hope this is useful,

 

tom

 

[ May 07, 2003, 06:58 PM: Message edited by: ZepSOFD ]

[G]

Thanks for that.

can you explain to me what value of the Physical Scale should be set to if i am using photometric lights and my units are in millimeters?

 

Thanks

 

G

[ZepSOFD]

G,

 

Physical Scale controls three things: Self-illumination, Reflection brightness, and as a multiplier for Standard lights(non-ies lights). Starting points are debatable, some start low and some start high, if you are going to start low start with 9000 and go up, if high start with a value right around that of the brightest light in your scene and go down. From 9000 to the brightest light, pretty much the only thing that will be effected is the brightness of your reflections, although you may see some changes in the brightness of self-illuminated bitmaps.

 

Hope this helps,

tom

[G]

thanks for your help, i shall give it ago.

 

G