TIFF/TGA/PNG/ETC textures with alpha channels not working properly

[The Pixel Artist]

There seems to be an issue with TIFF (and I think PNG/TGA/ETC) images that have alpha mask channels and being use in the opacity slot not rendering correctly, either in the preview window or when rendered.  Seems like the alpha channels is being flipped, but inverting the texture does not help.

Example image attached.

[Ondra]

what if you set alpha source to None in the texture?

[The Pixel Artist]

Doesn't seem to make any difference unfortunately.  I've attached the actual texture (but all TIFF/alpha textures I've try do the same).

[Ondra]

it should work if you set the alpha source to none in both diffuse and opacity textures, not just diffuse

[The Pixel Artist]

I actually did try try that, but it makes the whole object almost ghost-like.  See image.

Typically, with vray/MR/etc, you can just use the can TIFF image, instanced in both the diffuse and opacity slots, setting the mono channel to alpha and the alpha source to "Image Alpha", using the Premulitplied Alpha option

[gracelorn]

I am not sure, but I think inserting the CoronaMapOutput map between the bitmap and the material opacity slot might help. It worked for me, at least.

[Nupsi]

I´ve had the exact same problem with TIFFs and did everything you´ve said, Keymaster. The only workaround I found so far was to create an extra b&w-image ;-) Using Alpha 5 btw.

BR
Nupsi

[Ondra]

crap. Looks like there is a bug in 3dsmax here, because "use alpha as output" is not working correctly for RGB values

[fmistry]

I am not sure if I am doing something wrong here, but I am using Corona Version Alpha 6 with Max Design 2014 SP5. In the material opacity color slot, I placed a PNG file with transparency of a tree leaf. For some reason it doesnt map it right over the diffuse slot. I have tried every combination of Mono channel outputs, RGB Channel Output and Alpha source and with and without the Premultiplied Alpha check box (also the same with a TIFF file with alpha channel and transparency). It does work if I have a simple black and white JPG map for opacity. Am I doing something wrong or is this something that needs to be fixed in Corona.

Otherwise, Corona - AWESOME!!!

Okay, I guess i didn't read all the posts in this thread, but there is a work around. In the opacity map slot, you would have to put a CoronaMapOutput material and then place the PNG file in there with RGB Channel Output set to Alpha as Gray. However, you would not be able to use and instance of the map in the Diffuse slot since it would not display colour.

Would appreciate any input on this if I am going about this all wrong.

Thank you

[Ludvik Koutny]

I am not sure if I am doing something wrong here, but I am using Corona Version Alpha 6 with Max Design 2014 SP5. In the material opacity color slot, I placed a PNG file with transparency of a tree leaf. For some reason it doesnt map it right over the diffuse slot. I have tried every combination of Mono channel outputs, RGB Channel Output and Alpha source and with and without the Premultiplied Alpha check box (also the same with a TIFF file with alpha channel and transparency). It does work if I have a simple black and white JPG map for opacity. Am I doing something wrong or is this something that needs to be fixed in Corona.

Otherwise, Corona - AWESOME!!!

Quite simple... try other renderer, for example mental ray (Arch&Design material is Mental Ray's equivalent of CoronaMTL) and try to plug it into cutout slot of A&D material... If it does the same, then it's not Corona bug, but 3ds Max bug... and Max has quite of them when it comes to handling of various bitmap formats :)

[fmistry]

Yup. I tried out V-Ray which is the renderer I have been using for years. I never ran into the issue before, but never the less tried it out again. I used the same PNG with transparency as an instance in both the diffuse and the opacity slot, Mono Channel Output set to Alpha and it works perfectly. So I don't think its a 3DS Max Design bug. :)

[Ludvik Koutny]

Yup. I tried out V-Ray which is the renderer I have been using for years. I never ran into the issue before, but never the less tried it out again. I used the same PNG with transparency as an instance in both the diffuse and the opacity slot, Mono Channel Output set to Alpha and it works perfectly. So I don't think its a 3DS Max Design bug. :)

Great... thanks for testing... if you could upload super simple scene with the issue ready to be reproduced, i am sure Keymaster will take a look at it :)

[retort]

Great... thanks for testing... if you could upload super simple scene with the issue ready to be reproduced, i am sure Keymaster will take a look at it :)

I just ran into this bug now. Looks like it can be resolved by adding a coronaoutput shader.

I've attached a scene highlighting the problem.

max2012, corona v6

[jacobhutson]

in version 7 this behaviour is still there (aka not working)
it just doesnt seem to pulling the alpha correctly from PNGs (havent tried tiff or other formats)

the corona map output fixes it but difficult to do in entourage heavy scenes with hundreds of people
went back to vray to confirm the behaviour at works how you think, image transparency generates alpha output
in corona it doesnt.

hope you guys can issue an update as it prevent us from using our entourage collections.

cheers

[higgledyhiggles]

I`ve also always had this issue with the alpha channel not working and ever since I`ve used the Corona Map Output as stated to fix it. Some bright spark mentioned it before in another thread I think, I presumed it was a feature or there was a reason for it and I wasn`t clever enough to understand.