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adrian
05-22-2017, 02:08 AM
Hi I'm working on a massive scene so to save polygons I wanted to render out a line of trees separately so I could then apply the render to a billboard thus saving millions of polygons. As the trees are in the background that should've been fine.

So I rendered the trees on their own against a blue background, and then saved them from Layout in PNG32 format. I also saved the "Alpha" of the image in PNG32 format.

However as you can see in the image below the render is virtually useless because of all the blue in the image (if I use a different colour, there will be just as much colour spill with that colour). I applied the Alpha image as a clip-map but applying it as a transparency map has the same effect.

Is there a more optimal way of getting a decent clip map out of LW, or am I doing it wrong entirely? I'm using Xfrog trees which render beautifully with their own clip maps.

136833

luciano
05-22-2017, 02:15 AM
I Adrian, can you share only image and plane for clipping ...I would try


Hi I'm working on a massive scene so to save polygons I wanted to render out a line of trees separately so I could then apply the render to a billboard thus saving millions of polygons. As the trees are in the background that should've been fine.

So I rendered the trees on their own against a blue background, and then saved them from Layout in PNG32 format. I also saved the "Alpha" of the image in PNG32 format.

However as you can see in the image below the render is virtually useless because of all the blue in the image (if I use a different colour, there will be just as much colour spill with that colour). I applied the Alpha image as a clip-map but applying it as a transparency map has the same effect.

Is there a more optimal way of getting a decent clip map out of LW, or am I doing it wrong entirely? I'm using Xfrog trees which render beautifully with their own clip maps.

136833

adrian
05-22-2017, 04:35 AM
Sure, here is a .7z with the object and images. Thanks :-)

adk
05-22-2017, 04:50 AM
Instead of the usual Premultiply Alpha , have you tried ...
Render Globals>Output>Alpha Format = Unpremultipy Alpha ?

EDIT : Just checked out your scene after I posted. Seems your alpha is not correct. You could try tweaking it separately in the image editor in order to choke it appropriately or try what I suggested when you generate your image in the first place.

MonroePoteet
05-22-2017, 07:45 AM
If you can acquire the background plate / sequence for the final render, use that as the background for the tree line render rather than a solid color, or at least use a similar color as the final background will be. Since you're using an alpha channel rather than chromakey, there's no useful reason to have a bright-blue (or other keyable) background. As well, if you don't have the final background plate, you might set Ambient Lighting to 0% or the solid background color may bleed onto the surfaces of the leaves, bark, etc. Using the final background in the tree-line render will allow the most consistent lighting / rendering of the tree line.

mTp

adrian
05-22-2017, 08:39 AM
That's a good point- I'm using a Terragen4 created sky as the background plate so this could be the way to go. I'll also try the unpremultiply method suggested above to see if that gives better results.

adrian
05-22-2017, 12:21 PM
Using unpremultiply has made all the difference, no colour spillage that I can see at all, thanks a lot :-)