I created a lit particle system with very simple parameters: Default particle system> Added an unlit translucent particle with emissive > Added Light > Increased lifetime to 3 seconds > Decreased spawn rate multiplier to .25
The particles light the scene as expected (An amazing thing to watch, btw), however the specular reflections are significantly off.
I would expect the specular reflection to appear to move close to the camera/lower on the screen as the light source goes up into the air, however it stays directly underneath the lightsource (Or, projected horizontally)
In the screenshot, you can see this behavior. The lights on the right are displaying the expected specular behavior:
I think what’s happening here is that the particle light’s specular is being constrained by the light radius. The light radii have to be very small to be performant. You can make the radii bigger with the RadiiScale on the light module to test this. To visualize the radii you can set bPreviewLightRadius to enabled on the light module.
Usually what we do to get around this is to have two emitters, one has a large particle light radius with a very small count of lights, the other has a ton of lights with small radii. Then you still get some speculars showing up a good distance from the particles while having reasonable performance.
Unfortunately there are no tools to show you the performance impact of dynamic lights like these. It’s an important thing to have though.
Daniel,
I can’t agree with that assessment. Even if I pump up the radii in the particle system, it doesn’t place the specular at the reflected point on the ground plane, rather it places the specular directly beneath the particle. I have a demo scene and video showing it all more clearly, but this site isn’t allowing me to post any of it as it’s all over 512k 
I can email or post it another way if necessary.
–Tom
I setup a similar scene and got the same results with the particle speculars. This turned out to be a bug in the lighting shader which is now fixed and will be in the next beta. Thanks for reporting this and the detailed description!
I just wanted to note that this issue persists in the latest Beta (July).
Does it look the same as before for you or different but still wrong? I checked in the fix on 6/12 and the July Rocket build was made on 7/3, so that should have the fix. Can you open the log window when you have the editor and look for the line Version: at the top and past that here? I have
LogInit: Version: 1731698
It looks the same, I’m running 1711197, says it was added to my FTP on 7/2
I was able to duplicate it on that version you have Thomas, which is odd since it was made after the fix was put in. Looking into it, and will let you know what I find.
I’m at a loss. Here’s what I see. The speculars are reflected in a line like I would expect.
From asking around here, looks like the July build was branched before my fix, even though the cl says it was later. Guess you’ll have to wait one more build =(
Thanks for checking into it 
I’ll shelve the fireworks systems till then!
Hello,
Thank you very much for your submission. After reviewing your issue, I was able to reproduce it. I have added a report to our database and assigned the problem to a programmer. Please do not hesitate to let us know if you encounter any more issues.
-Alexander
