From: "Brendan Bolles" Received: from nail.lmi.net ([66.117.140.18] verified) by media-motion.tv (CommuniGate Pro SMTP 6.1.0) with ESMTPS id 6454097 for AE-List@media-motion.tv; Wed, 23 May 2018 04:16:46 +0200 Received: from [10.25.0.53] (unknown [12.42.42.62]) by nail.lmi.net (Postfix) with ESMTPA id 738EDE4215 for ; Tue, 22 May 2018 19:23:29 -0700 (PDT) Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Apple Message framework v1085) Subject: Re: [AE] Inverse Square Law for glows In-Reply-To: Date: Tue, 22 May 2018 19:23:11 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: "After Effects Mail List" X-Mailer: Apple Mail (2.1085) On Apr 19, 2018, at 10:41 PM, Chris Zwar wrote: > Sure it looks good but I don=92t think it=92s 100% mathematically = 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 = inverse 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 works = 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