This is probably a silly question but none-the-less why do the Force Additive mode particles appear to be twice+ the size of non forced additive mode (ie no lights just alpha) in a same frame render? Don’t really know why I haven’t noticed this before, I would think that they would be the same.
Also why is there no Alpha render element? You have all the others ie diffuse/specular/emission/ect.
As discussed in another thread, when the Filtering is set to Bilinear, a single particle will occupy a 2x2 pixels square, and with Bicubic it will use 3x3 pixels. Normally, when the Density is low enough, most of these pixels will be barely filled. But if the Density is very high, then all 4 or 9 pixels can get filled with values greater than 1.0, producing very large-looking particles.
Force Additive mode of course produces no Alpha channel.
The reason there is no Alpha Render Element is that EVERY image written out by Krakatoa when Force Additive Mode is OFF will contain an Alpha channel anyway.
The main RGBA image will contain the Alpha, the Z-Depth will contain the Alpha (normally it will be non-anti-aliased, but if you enable the Filtering in the Render Element, even the Z-Depth will produce an Alpha matching the RGBA’s Alpha) and so on.
Of course, when rendering in Force Additive Mode, there will be no Alpha and also no Render Elements will be really output because there will be no way to know what particle is in front (since all particles’ values are basically summed together). All Render Elements will appear black and with no Alpha.
Here is a closeup of a single particle rendered with Nearest, Bilinear and Bicubic Filtering:
Here is the same particle rendered with Emission and very high Emission Strenght:
Ah, sorry, I wish I would have seen that other thread but anyway, great examples. Thanks for those. Such a quick setting (now that I understand it better) I had been rendering over and reducing to compensate, with no lights its certainly doesn’t take much longer to render larger, this is much better.
As for the alpha, RGBA has a way heavier per frame footprint sometimes double or triple the memory size, if you just need an alpha, that’s all. It just seemed natural to have an alpha RE since you have most others. No big deal by any means, I was just curious.
These screenshots are from an upcoming documentation page that will be discussing the particle rendering and Filter modes in more detail. It is expected to appear on Monday.