View Full Version : bloom or corona error

07-01-2004, 05:07 AM
the bloom & corona effect is not showing up correctly when I render out to final. In the small version I rendered to for a concept, it looked correct. When I rendered a large version, the effects were not showing as much. The only difference between the 2 attached images is the camera dimensions and the pixel ratio.
-Small version is 320 x 240 pixel aspect ratio is 1.0.
-Larger is 720 x 486, pixel aspect ratio is 1.2.
Any ideas on why is looks so different in the larger version?

07-01-2004, 11:48 PM
So what have you learned of this? Image filters calculate based upon absolute size/ total pixels and don't factor in any resolution settings. So next time do your tweaking at full res...


07-02-2004, 03:03 AM
Yes I do remember reading that settings are based on an average render and you have to adjust the settings when rendering bigger n smaller!

07-02-2004, 03:31 AM
If you use the size multipliers in the Camera Properties window you can test at a lower resolution than your final render. So if you were to use your final render resolution, but a multiplier of 25%, you would see exactly what you would get in your final, but at a smaller size.


07-02-2004, 04:46 AM
Nope, I found that this in most cases doesn't work properly. Yes, it works fine for LW's own lens flares and glow, but not on filters. There seems to be a problem in how the buffers are scaled and hence quite often the results do not look as they should. Doesn't matter much since I find it useless to tweak anything at such low resolutions even with surfaces and other settings. There is always some pixels being interpolated and thus different from the large res and you can't really control quality.


07-06-2004, 01:50 AM
OK, I was doing some tests on this problem. I noticed that when I rendered the frame @ full size, when the bloom filter was processing (you can watch the progress 25%, 26%...you get the picture) it would go rather slow up to about 42%, then suddenly jump to 100% and be completed with the bloom instantly. It's almost like LW decided not to render out the remaining part of the bloom. I then did a limited region render of the full size frame...and LW decided to render out the bloom to full effect now? Any ideas?



07-06-2004, 02:55 AM

LWs bloom/corona only calculates pixels bright enough however, so jumps in the percentage display are normal.

I've started writing my own bloom filter a while ago, but haven't touched it for quite some time. If you're on a PC feel free to mess around with it...

Doesn't account for pixel aspect however...but i'm not even sure if LWs does.

07-06-2004, 03:53 AM
Thanks for the plug-in offer, but Mac user here.

Also, I no longer think it's the pixel aspect ratio that's causing the problem. That's why I posted my last message. The error only occurs when I render then entire frame, but if I render only a portion, the bloom renders correctly. It's almost as though LW is "running out of steam" to calculate the complete bloom effect for the entire frame. I may to load the scene on a G5, see if that somehow fixes it, we'll see.

*thanks again for the plug in offer, very generous of you!

07-06-2004, 09:32 PM
Corona is a Kinda quirky. It helps to think of it as if you're taking the image into Photoshop - it has almost nothing to do with Lightwave's 3D.

I don't know what settings you're using, but when you use Limited region, Corona still calculates the black areas outside the region, like all other post-process filters. It could be looking at relative pixel brightness, an average, which would be different than a full frame. If you do your test renders at full frame you should be able to find a setting that works.

07-07-2004, 04:55 AM
no I don't think it's that. I've isolated the problem from where I can see it, but now I'm waiting for newtek to get back with me. Lightwave is having problems in calculating the filter. It doesn't follow through with 100% of the filter. I can watch the % count up slowly when rendering a full frame, then around 42%, it suddenly jumps to 100%

07-07-2004, 11:58 AM
As mentioned before, the percentage can jump because Corona is telling you how far it's gotten through the image, not how much of the work is done. For example, if the top half of the image is black, the percentage will jump to 50% almost instantly. In your case, the limited region area is only 42% of the image, and Corona calculates the entire image with or without limited region - so when it gets to the black areas, it goes really fast.
It does the same thing on everybody's machine.

07-07-2004, 12:23 PM
Alright, let's forget about the whole % thingy.
Bottom line, Bloom works fine when I do a limited region rendering, of the full sized frame. But, when I then try to render the entire frame, it doesn't produce the same result as it did with a limited. So, what gives newtek!

I posted these earlier, but here they are again.



07-07-2004, 01:10 PM
Stupid question, but does the whole frame have Bloom at all, or does it look the same without the filter?

I just did a quick test, and it looked the same on limited region, except near the borders of course...on PC that is however.
But i don't believe you have that little RAM so that it aborts on full resolution or something...
(just out of curiosity, how long does it take for the bloom?)

meanwhile i'll rack my brains over how to improve my own plugin :)
Then Richard may have to do another compile job...