[deflix]

Im a bit stuck with this relatively simple problem. Im creating a clipped material with ior 1, and a black and white map in the transmittance and correspoding photo in reflectance 0. I dont think I've done anything wrong here, except the resuklting rendering looks semi-transparent all over.

Any ideas would appreciated as am trying to hit a deadline.

cheers

[deflix]

Im starting to suspect a bug with how maxwell handles clipmaps. Ive tried a few different blackandwhite images and have normal results - further tweaking in PShop has created this image (half normal half semi-transparent), which suggests a bug. Any further light on this would be great.

As you can see from the screenshot below the rendering and corresponding clipmap dont make sense. The material is applied to a plane.

[choo-chee]

I've noticed you use .jpg for clipmap? big mistake. it will not render good because the values are not 0,0,0 255,255,255 for the clipmap. use only TIF or TGA with absolute values.

[deflix]

Re-Saving the clipmap in a different format yields this result.....i.e. no improvement (this is a tif).

Is this suggested issue of file format unique to maxwell? I've never encountered this before and have always use jpeg or png for maps for over 10 years!

Can someone from NL please give me a pointer................!

[choo-chee]

check the map to see there are no numbers like RGB 254,255,255 or 1,0,1 etc.... I had the same problem. Re-saving without useing Photoshop fill for white areas at 255,255,255 and black areas 0,0,0 will not be good enough. You have to open the map, magic-wand select the white, fill it with F5 and "white" then inverse selection and fill F5 with "black", then save as TIF.

[deflix]

thanks for your help choo chee. Although it raises more questions and my level of frustration. Clipmaps should be capable of resolving all shades from white to black - when did you learn that the map must comprise only pure white and pure black?

Surely the relationship between black and white is a linear relationship between pure transparency and pure opacity.

I'm not sure I understand the problem.

seems like a bug to me.

[deflix]

Ok - so this is an important one to mention. Clipmaps in MAXWELL have to comprise only pure white or pure black. or they dont work properly. Why isnt this in the manual?!?

again thanks for your help choo chee. youve saved me alot of time.

[choo-chee]

no problem.... I did this for about 300 images for an animation sequence with Marlin's people in motion

[Bubbaloo]

Clip maps used in that way (in the transmittance slot) need to be 0 or 255. There is another way to do it; use a second layer and use a greyscale image to weight the transparency. This way is much more flexible. Invert the clip map on the other layer and that will be your visible layer. In this way, you can fade from fully transparent to fully opaque.

Also, with clip maps put in the transmittance slot, make sure that image filtering is turned off. This used to be a problem, but I think they might have fixed it. Not sure.

[deflix]

Clip maps used in that way (in the transmittance slot) need to be 0 or 255. There is another way to do it; use a second layer and use a greyscale image to weight the transparency. This way is much more flexible.

Thankyou too bubbaloo!

(nice rhyme)