View Full Version : Random clusters of white pixels

03-14-2019, 02:14 AM
Using Lightwave 11.6.3 I completed three scenes of some letters flying into the scene, then cascading to the ground, then disappearing below ground level.

I thought I would recreate the three scenes using 2019.2. All was fine until I viewed the resulting .png files and noticed virtually all frames rendered had what seems to be totally random clusters of white pixels dotted over the frame area. I haven’t changed any of the default settings within the Render Properties dialogue box.

Can anyone let me know what I have done wrong and how to fix the problem (this didn’t happen using 11.6.3?)?

Kind regards


03-14-2019, 03:54 AM
Sounds like fireflies (specular hotspotting)... 2018/19 is a very different render engine, it's rare that anything just straight ported over from earlier versions will just work as expected without a bit of love.

Start with this lot...


03-14-2019, 07:47 AM
Hi RebelHill
Since my initial post I have been reading the online documentation and I seem to have found a fix? I have checked the “Despike” box within the Render Properties dialogue box and left the tolerance level as the default setting. The resulting .png files have no clusters of white pixels at all.

This is what the online documentation says:

Enable Despike
Despike examines buffers for anomalous spikes in their data while rendering and attempts to smooth them out.
Despike Tolerance - Defaults to 0.8, any brightness below 0.8 will be affected by neighboring samples. Do not use Despike unless you have actual bright spikes in the render you want to remove.

I have one concern however, that being the last sentence doesn’t say why you should not use the Despike option?

Have I always got to render a frame, check if there are no white pixels where they shouldn’t be, if I do find some then I will have to re-render the frame using the Despike function. Using this method could potentially double my time? The Despike method doesn’t add any render time compared to not using it?

03-14-2019, 08:15 AM
Well... I'm not sure how it is you can have any idea of what it is you're going to get from a render if you don't test render along the way while setting up a scene.

As for despike, it's certainly useful for cleaning up these things, but it's not a universal fix, nor without potential downsides... you really want to set your render up correctly in the first instance so as you minimise any errors or problems before resorting to the post render cleanup tools.