From: "Byron Nash" Received: from mail-qk0-f175.google.com ([209.85.220.175] verified) by media-motion.tv (CommuniGate Pro SMTP 6.1.0) with ESMTPS id 6454569 for AE-List@media-motion.tv; Wed, 23 May 2018 18:58:10 +0200 Received: by mail-qk0-f175.google.com with SMTP id k86-v6so2420991qkh.13 for ; Wed, 23 May 2018 10:04:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=sGoYRr6RLjSdzP1MMnwFDpuFnQghgMJFRWmEdFWVOqU=; b=LFmxN2yvhuTWYtdFdqTnX4HNni99ul9Ep8VbisXAuUblTLp9mkg8KeB5sghSJwOEmG FH7t+glOlT6C4xvg/TXT0SnqwmKngRBpBrTt7XLIyYB4ygNwMCKDyL0iNmXT5LNsNvGe SCK+LXDIwBIzwd5KtN896YUlaAJKMV62oZyRM/q/eN4u6Ay04KuMdpQFhqYsjuTv1XqF SGXwgMSx7v8YWiIv+RAf6bpEpjjNws3wYB4kYsVJWZLzKbtKBf8L/9jIL/2T4tmzWaRv 3FNnEENw/OYO6hCBqaD8+uv1kGV8oLxGtxFspeiq4QDvlPC4MpY1aljXgbfqGTMlIlqF GKvw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=sGoYRr6RLjSdzP1MMnwFDpuFnQghgMJFRWmEdFWVOqU=; b=jr5bc7/8jr9eGrGGpiSFcmeZj1FicEfvTZnWYJF0pXdU0YFZ0zObkpFZ8gtx0MKFdi RKxmqzHci5Ql1blUsZf7y68v8C+6GofGDhGbJJWwfdK7PoikuakQbYJ2Nctwhj/w4K7f w6ITtgMA8/el9K6fgwnigKOwqXUZAk5B5TXbFvKVR6YpSkB/tPZjyA2OAtGVGjsb2Akf 8bZlmYiqWNu6NIbjRI8YR1MJ55lfFhM4L+ZOZt+D871nqnU5+pU9iv+L9rz28mwK+10c IIIMra6qMPeecTwoRAWA+OScMAWygr9P7mEgMjW45oqIuLDrXqAl9qczyfAphc99d2yf ZERA== X-Gm-Message-State: ALKqPwdObAofJMS52Suo3DamByLOTx/SQ8O6v8xuG5Ay00BSGbeZ8Ws9 A690CPfxGzhmSjVYZZz3aYY3DGJSLP11iEfeCOg= X-Google-Smtp-Source: ADUXVKLs1X6yiAxWKcqRdKmfIB/1C0KzYLhezhBa4g7IWp44NxzrRQwj23YF/HltbGsbEatdb2+3ZOIc1hC3+DkQDok= X-Received: by 2002:a37:2a8e:: with SMTP id q14-v6mr2891641qkq.380.1527095095070; Wed, 23 May 2018 10:04:55 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: Date: Wed, 23 May 2018 13:04:43 -0400 Message-ID: Subject: Re: [AE] Inverse Square Law for glows To: After Effects Mail List Content-Type: multipart/alternative; boundary="000000000000ae13f2056ce28864" --000000000000ae13f2056ce28864 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Love it. Thanks Brendan. In my case I had an expression that looked at the layer below it and multiplied it by 0.9 or something for each extra layer. Don't have it in front of me but it came out well which is all that matters. I do enjoy knowing the real math involved even if it goes over my head. I think it helps in creating more predictable and accurate VFX when you at least make some effort to reproduce it as it is in nature. On Wed, May 23, 2018 at 6:14 AM Chris Zwar wrote: > That=E2=80=99s awesome :-) You make it sound so obvious... > > > On 23 May 2018, at 12:23 pm, Brendan Bolles > wrote: > > > > On Apr 19, 2018, at 10:41 PM, Chris Zwar wrote: > > > >> Sure it looks good but I don=E2=80=99t think it=E2=80=99s 100% mathema= tically perfect. > > > > > > I'm a little late to this thread, but... > > > > I don't think glow is inverse square, the apparent brightness of an > object as it moves away from you in space is. If glow were simply invers= e > square, you could simulate the falloff by applying Levels with gamma 0.5 = to > your 0.0-1.0 linear falloff. > > > > Actual glow in the real world is a function of how many bounces the > light does in the lens/air before getting to the film/CCD through a > non-direct path. Depending on the circumstances, only a fraction of the > light gets scattered in a certain direction, and then only a fraction of > that is scattered back to the camera. Sounds more like a logarithmic > falloff than inverse square. > > > > Not having a logarithmic falloff plug-in, the multiple blurs thing work= s > pretty well for me. In line with the logarithmic thing, I usually do some > sort of expression for glow radius like: > > > > glowRadiusStart * Math.pow(glowStep, glowLayerIndex) > > > > This gets big quickly, but that's the idea! > > > > And of course, to physically simulate glow you'd want a linear float > color space with Add mode for each layer and the glowing object to be way > over 1.0. Then because air/glass is pretty transparent I usually set the > Transparency of each layer to 1% or so. > > > > Bonus points if you then bring the whole thing down a smidge (Levels > output white 0.96 or something) because the glows added extra energy but > the sum total of post-glow energy should be the same as the pre-glow. > > > > > > Brendan > > > > > > +---End of message---+ > > To unsubscribe send any message to > > > +---End of message---+ > To unsubscribe send any message to > --000000000000ae13f2056ce28864 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Love it. Thanks Brendan. In my case I had an expression th= at looked at the layer below it and multiplied it by 0.9 or something for e= ach extra layer. Don't have it in front of me but it came out well whic= h is all that matters. I do enjoy knowing the real math involved even if it= goes over my head. I think it helps in creating more predictable and accur= ate VFX when you at least make some effort to reproduce it as it is in natu= re.=C2=A0

On Wed, May = 23, 2018 at 6:14 AM Chris Zwar <AE-List@media-motion.tv> wrote:
That=E2=80=99s awesome :-)=C2=A0 You make it sound so obvious...

> On 23 May 2018, at 12:23 pm, Brendan Bolles <AE-List@media-motion.tv> wrot= e:
>
> On Apr 19, 2018, at 10:41 PM, Chris Zwar wrote:
>
>> Sure it looks good but I don=E2=80=99t think it=E2=80=99s 100% mat= hematically perfect.
>
>
> I'm a little late to this thread, but...
>
> I don't think glow is inverse square, the apparent brightness of a= n object as it moves away from you in space is.=C2=A0 If glow were simply i= nverse square, you could simulate the falloff by applying Levels with gamma= 0.5 to your 0.0-1.0 linear falloff.
>
> Actual glow in the real world is a function of how many bounces the li= ght does in the lens/air before getting to the film/CCD through a non-direc= t path.=C2=A0 Depending on the circumstances, only a fraction of the light = gets scattered in a certain direction, and then only a fraction of that is = scattered back to the camera.=C2=A0 Sounds more like a logarithmic falloff = than inverse square.
>
> Not having a logarithmic falloff plug-in, the multiple blurs thing wor= ks pretty well for me. In line with the logarithmic thing, I usually do som= e sort of expression for glow radius like:
>
> glowRadiusStart * Math.pow(glowStep, glowLayerIndex)
>
> This gets big quickly, but that's the idea!
>
> And of course, to physically simulate glow you'd want a linear flo= at color space with Add mode for each layer and the glowing object to be wa= y over 1.0.=C2=A0 Then because air/glass is pretty transparent I usually se= t the Transparency of each layer to 1% or so.
>
> Bonus points if you then bring the whole thing down a smidge (Levels o= utput white 0.96 or something) because the glows added extra energy but the= sum total of post-glow energy should be the same as the pre-glow.
>
>
> Brendan
>
>
> +---End of message---+
> To unsubscribe send any message to <ae-list-off@media-motion.tv>


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