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Alpha Gloss & Reflectivity


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Hey, gents! 

Recently I've been working on yet another revision of the 3rd P.G's SPADs, to "fill in the historical blanks" that I missed with the last iteration. One thing that has been most irritating has been trying to perfectly replicate the unique appearance of the French dopes that were used to paint USAS SPAD XIIIs.

For a little context, French 5-colour dope had aluminium powder worked into the dope. A very thorough USAS report from 1918, about the mixing and application of these dopes, stated that "The surfaces are neither glossy nor dull but can be highly reflective", which is what I've been trying to emulate. 

After weeks of tweaking, re-tweaking, and generally slipping ever-further into madness, I was pretty gutted to find out that the unique effect...can't really be done in FC. Well, it can, but the way reflectivity works with the template, it makes the wings look like they're made of glass rather than fabric.

However, I did come up with a little chart to try and save any fellow skinners the nightmare that is trying to find the perfect shade of grey for your alpha channel! Hopefully some of the skin makers here will get some use out of it! 

gXHikbU.png

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One way to emulate the woven fabric might be to work with the normalmaps. However, as one who has done many real life dope and fabric jobs on full size aircraft, the weave usually isn't visible. That may have been different in early WW1 jobs with just minimum coats of clear nitrate dope but once you start using aluminum dope the weave gets filled.

EDIT: (I should have read your post more closely... you are not talking about the fabric weave... still, I wonder if playing with the textures of the normalmap might have an additional illusion in regards to reflectivity and gloss.)

As you have no doubt found (as I see from your graph), the difference in the gray percentage for slight gloss, high gloss and matt is very tricky and seems to vary throughout the surfaces of the planes. Have you tried grays (flat throughout) with no textures / shadows in the alpha?

Interested to hear of your findings. 

Edited by Vonrd
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  • 2 weeks later...
On 11/29/2020 at 7:32 PM, Vonrd said:

One way to emulate the woven fabric might be to work with the normalmaps. However, as one who has done many real life dope and fabric jobs on full size aircraft, the weave usually isn't visible. That may have been different in early WW1 jobs with just minimum coats of clear nitrate dope but once you start using aluminum dope the weave gets filled.

EDIT: (I should have read your post more closely... you are not talking about the fabric weave... still, I wonder if playing with the textures of the normalmap might have an additional illusion in regards to reflectivity and gloss.)

As you have no doubt found (as I see from your graph), the difference in the gray percentage for slight gloss, high gloss and matt is very tricky and seems to vary throughout the surfaces of the planes. Have you tried grays (flat throughout) with no textures / shadows in the alpha?

Interested to hear of your findings. 

I've not dabbled in normal maps much but I'll give it a go! 

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4 hours ago, DeFreest Larner said:

I've not dabbled in normal maps much but I'll give it a go! 

I haven't either except for a couple of ventures into trying to make mud spatters look more 3D... still in process.

I was thinking that maybe manipulating the "texture" (see the square between the rib bays, this is the normal map from the SPAD) might allow the illusion of the proper dope "sheen". Not sure if it needs to be more or less.

I know that you love a challenge 😏

I'd love to hear your findings if you do give it a shot. I'll do the same but I'm deep into revising our skins and don't have much spare time.

Normalmap.jpg

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On 12/8/2020 at 4:45 AM, Vonrd said:

I'll do the same but I'm deep into revising our skins and don't have much spare time.

Ain't it fun being the Paintmeister for a four-squadron group? If anyone can relate, it's me (also currently overhauling our XIIIs) 🤣

I'll definitely be delving into the Normal Maps for the XIII. 

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