<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On 08/09/2007, at 5:24 AM, Alfredo de Greef wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">(btw, about the HDR aliasing problem, as I mentioned</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">to broken some time ago, the way I dealt with that in</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">yafray is simply by clamping/tone mapping *before*</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">anti-aliasing, not afterwards. Of course, as broken</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">then remarked, I forgot about the compositor. If the</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">compositor had full access to all samples that would</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">solve that problem, but the data would then probably</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">be quite unmanagable, at least in its current form)</DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV>But then I also had an idea too, that you could clamp/tone map before AA by default, but also provide the un-clamped (or just the overbright values) as a render pass. So in situations where you need the HDR colours, they are available to use, and in situations where you don't, you don't need to incur any memory overhead. If I recall correctly, the RPF format provides this as one of its render pass slots[1] so it's probably done in other apps too.<BR><BLOCKQUOTE type="cite"></BLOCKQUOTE></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Another idea is to a) clamp the pixels before AA, but then b) go back over the final AAed image, and for each pixel that is clipped at 1.0,1.0,1.0, fill in the original HDR values. This would mean that the transition from light to dark is within 0.0-1.0 but you still get the overbright values to do stuff with later, like blurring for example. Check this comp to see a bit of an example of what I mean here: <A href="http://mke3.net/rt/aa_hdr.blend.zip">http://mke3.net/rt/aa_hdr.blend.zip</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Of course there's lots of clever people on the case to solve it, but the rendering to 4k idea would scare me a bit if I was working with it.. Rendering to 4K means a lot of memory used, if only just for the render buffers. At work (on Windows of course which isn't too good at this) I've had huge problems rendering 5k+ images for print with multiple render layers/passes, if only just because of the amount of memory that needs to be allocated at the start and comp stage of the render, when using lots of passes/layers. I wouldn't be looking forward to comping 4k images either, it's slow enough right now at HD... Doing the render 4k/scale down method also seems inefficient - in effect, it's like having full oversampling switched on for every pixel in the frame, whether it needs it or not, no?</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>cheers</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Matt</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>[1] <FONT class="Apple-style-span" face="Helvetica"><A href="http://www.fxguide.com/fxtips-114.html">http://www.fxguide.com/fxtips-114.html</A></FONT></DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Lucida Grande; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Lucida Grande; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Lucida Grande; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV>------------------------------------------</DIV><DIV>Matt Ebb . matt@mke3.net . <A href="http://mke3.net">http://mke3.net</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN></SPAN></SPAN> </DIV><BR></BODY></HTML>