16 bit Tiff in Maya to Mental Ray

#1

I appologize if this has been addressed already - but I’ve searched through the forum here and found nothing.

I’m using zBrush to create displacement maps as 16bit Tiff files which I’m importing into Maya. The tiff file loads fine when I place it in my displacement file location, but when I begin a render, MentalRay comes back with an error relating to the file. Why?

When I bring the 16bit tiff back into photoshop, drop the bit depth down to 8 and export it, I can render no problem. Again - I’m sorry if this has been addressed already.

  • LordAurasia
#2

Mentalray doesnt like compression in tiffs. Maybe try to resave the 16-bit tiff without lzw compression.

#3

Tried that … as well as all of the other tiff compression options in PhotoShop. I’ve done it with layers, without layers … the one I just tried is uncompressed tiff with no layers. It’s a 2048 by 2048 size tiff at 8.00 MB - that sounds right doesn’t it? Still no luck - Mental Ray crashes as soon as the render starts even though Maya reads the file and updates the little thumbnail … sigh

#4

Hmm. Have you tried saving it as a png?

If youre going for deeper bit-depths, you also might try using the openEXR format:

http://www.openexr.com/

#5

Seems like it liked the PNG solution. Thank you for helping me! I hate asking dumb questions - but I know that there are helpful people out there who will take the time to help us younger explorer’s out … despite our simplistic idiocy sometimes. :wink:

Thank you.

#6

Solution is simple dude. Convert the tiff image from greyscale into RGB. Zbrush outputs displacement maps as greyscale tiffs.

You can then open it up in photoshop,go to Mode or something and change to RGB and resave the tiff. Mental ray will read it fine then.

Regards,

Marlboro Man

#7

Marlboro-Man,
wouldn’t that rescale your 16 bit greyscale into an 8 bit mode? You’d be losing a whole ton of data then, wouldn’t you? 32 bit ‘color’ is 8 red, 8 green and 8 blue as well as 8 for alpha. But isn’t a 16 bit greyscale 256x256 (65,536) shades of grey? That would be what I would understand a 16 bit greyscale to be in the first place, so converting it to an 8 bit would be going from 65000 to 256 … I could be wrong, it wouldn’t be the first time, but enlighten me if I am.

#8

I figured out the problem. Mentalray isnt able to handle grayscale format tiffs, spitting out the error:

IMG  0.0  error  101003: //my.tif: file format subtype or version not supported

I guess you should be able to convert the grayscale to rgb, since grayscale mode simply means one 16-bit channel (grey) instead of three (red, green, blue). Saving as png does this under the hood by the way, it outputs a 48-bit image (3*16-bit, three channels). So if you convert to rgb in photoshop, you actually copy the 16-bit channel into three other 16-bit channels - quite pointless (three times the same information), but it should work without loss.

#9

What Malboro-Man says is save your image into an 16bit rgb file instead of
16bit grayscale file.
you will still retain your bit depth info since photoshop will convert
your grayscale texture into rgb ‘color space’ and each channel (r,g,b) will still be
16 bits instead of 8.
And dont forget to save your file with no compression.

Good luck with your project.

EDIT:

anyone knows a windows command line utillity that supports 16bit and compression?
imgcvt supports only 8 bit(and maybe 12) and imconvert(ImageMagik)
doesnt support LZW.

-
#10

imf_copy (in your maya/bin dir) handles exr with different kinds of compression like rle, zip, piz and whatsoever. Havent tested it with exr though.

#11

Floze, imf_copy and imf_disp doesnt support LZW compression which is what i am after.
try to imf_copy convert a LZW tif image to say an iff or map file with verbose on.
For everything else i`m cool, i have 3-4 command line converters
(imf_copy, Fcheck, imgcvt, ImageMagik)

Thanks though

.

#12

Ok…

Basically, all the technical stuff aside, converting the greyscale zbrush tiff into Rgb works flawlessly. If you test render you will see.

Do not use any form of compression on the tiff. Mental ray doesn’t like it too much. I’ll let someone do the explaining of the 16 bits and 32 bits … as I’m not very savvy at that. I just know what works and what doesn’t, simplistic mind eh ? hehehe

Regards,

Marlboro Man

#13

and as another tip, when you open the file in photoshop always make sure ‘color management’ is set to OFF or it will mess up your mid-level grey in the displacement.

that or you might end up with something like this:

doughboy.jpg720x480

haha…once a head now a doughboy!

#14

Have you tried irfanview? It has a powerful batch processor, and as far as I know you can use it via command line as well. It doesnt support the maya specific formats though (iff, .map, etc.)

http://www.irfanview.com/

#15

hey Nix21!

Man, that’s a great rendition of crusty the clown! nice stuff :slight_smile: LOL

Marlboro Man

#16

Ok - I’ve played with this a little more and found a couple solutions that worked based off of everyone’s feedback and help. I just wanted to post one last time to say thanks. I think the next problem I’m going to have to address will be more zBrush related than maya/mental ray. At any rate - thank you everyone.

#17

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