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Thread: Billboard objects with transparency - one map?

  1. #1
    May the sauce be with you starbase1's Avatar
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    Billboard objects with transparency - one map?

    Hi All,
    I'm wondering if I'm missing something here...

    I'm about to make a big bunch of renders with a transparency channel for use in billboard objects. i.e. a simple oblong polygon, with a transparency channel.

    Is there a way of picking up the transparency from the 32 bit PNG? Without using a separate transparency map?

    Cheers,
    Nick
    Specialist subjects: Unflown space projects, and the space program of the Soviet Union.

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  2. #2
    Super Member Kryslin's Avatar
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    It should work as is. However, to be safe, and to avoid increasing your render times because of Ray Recursion increases, I'd use a clip map, transparency map, and your texture map. Yeah, I realize that increases your overhead a bit. But, you won't have to up your ray recursion levels too much because of the transparency, because any hit on the clip map isn't counted as a ray hit.
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  3. #3
    Registered User motiondigital's Avatar
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    Hi starbase1

    Create a uv map of your billboard (See image_01.jpg)

    Create 2 surfaces on your billboard a) a Transparent surface (See image_02.jpg) b) a non-transparent surface (See image_03.jpg)

    For the non-transparent surface:
    In node editor plug your textures colour using your uv map into the colour channel (See image_04.JPG)

    For the transparent surface:
    In node editor plug your textures alpha using your uv map into the refraction index channel (See image_05.JPG)

    If you are doing branding, (Same geometry - different packaging designs - use an image sequence and number the images as follows: image.001.png, image.002.png, image.003.png etc (See image_06.JPG)

    if there are 20 images in the sequence set your animation to 20 frames load first image of a sequence into the image editor (See image_07.JPG)

    See end result (See image_08.JPG)

    Click image for larger version. 

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  4. #4
    Registered User motiondigital's Avatar
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    Image correction: image 3 shows the label selection (The previous image I uploaded show label and window as being selected) Hope this helps

    Click image for larger version. 

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  5. #5
    Curmudgeon in Training Ma3rk's Avatar
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    If ya happen to have OD Tools ...

    https://vimeo.com/275159712

    but this is with images already w/ alpha. So, just use this as a guide for your renders.
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  6. #6
    wow didn't know i had that, thanks for reminder, on a Mac embedded alphas never work, usual workflow is is to instance the image in the Image Editor, set the instance to 'alpha only' and use that for clip map, that approach might work for you

  7. #7
    Super Member XswampyX's Avatar
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    As Kryslin said you want to use the clip input else you will end up with black bits all over your render.

    Something like...

    Click image for larger version. 

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  8. #8
    Curmudgeon in Training Ma3rk's Avatar
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    Quote Originally Posted by gerry_g View Post
    wow didn't know i had that, thanks for reminder, on a Mac embedded alphas never work, usual workflow is is to instance the image in the Image Editor, set the instance to 'alpha only' and use that for clip map, that approach might work for you
    I've had hit & miss luck with pngs' & their alphas as well. Just assumed it was how a particular piece of software implemented some aspect of the standard. I've done what you do as well as just break out a separate file as the alf.

    Still a little miffed at Affinity Photo for not fixing whatever it is that won't allow SuperPNG plug-in to load.
    Earth can't be flat otherwise cats would have pushed everything off the edge!

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  9. #9
    May the sauce be with you starbase1's Avatar
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    Wow! Thanks for all the responses.

    I think I'll go with cloning an image and setting one to alpha only. A quick test shows I can replace one of the images, and the clone changes too.

    I'm happy with increasing trace depth, as:

    a) Its a simple scene
    b) Let the computer do more work, not me...

    Nick
    Specialist subjects: Unflown space projects, and the space program of the Soviet Union.

    My main Web site

  10. #10
    Eat your peas. Greenlaw's Avatar
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    Yes, clip map...it's much faster. I use this for instanced cards and objects all the time.

    The only 'drawback' is that a clip map is single-bit so it doesn't have AA or allow for transparent gradients. However, that doesn't mean the edges won't get anti-aliasing in render (it will,) and if you really need semi-transparency in the image, you can combine actual transparency in shading along with the clip map to get some of the benefits of both methods.

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