Good morning,
I have a question regarding increasing the bloom of emissive lights, and visibility of light shafts of point light functions in volumetric fog.
Currently the bloom effect of emissive lights seems to be limited by distance. As I move away from the lights, the bloom intensity and effect radius decreases significantly. I have tried changing some settings in the post process volume, and the volumetric fog, but I have not been able to figure out how to maintain the size and intensity of the bloom as I move away from the light source. Specifically, I have been changing scattering distribution in volumetric fog, and bloom intensity and threshhold in the post process volume. Increasing bloom intensity helps a lot, but unfortunately it also increases the bloom from directional lights, which I do not want.
I’m having a similar issue with the point light function. As I move away, the light shafts from the point light are culled.
Do you have any suggestions for how I can get bloom to maintain its appearance, and enable light shafts for point lights at large distances? We are not using Lumen.
Thank you,
Sean Robinson
Hello,
Thank you for reaching out.
I’ve been assigned this issue, and we will be looking into the bloom and light shaft behavior you are describing.
We were unable to reproduce the behavior as described.
Can you please send us a minimal test project that demonstrates this, and include screenshots of the issue?
The guide for test projects:
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Good morning,
Here is a sample project containing fog with a point light and an emissive sphere.
For the point light notice that the light shafts are visible close up, but they disappear after the camere is beyond a certain distance.
For the emissive sphere, the light scattering and bloom in the fog is visible at large distances, but it is not very large. I want to increase the size and intensity of this effect without increasing the emissivity. I am working with real lights whose emmisivity values shouldn’t be changed. I also do not want to increase the fog density just to improve these lighting effects. Is there another way to increase the size and intensity of the bloom and light scattering in fog?
Thank you,
Sean Robinson
Hello,
For the point light, it is important to understand how the fog is rendered. Volumetric Fog uses a voxel system in screen space to store light contribution to fog in-scattering. These voxels are stored in a 3D texture, which is limited in size. The point light ceases to affect the fog when it goes outside of this volume.
You can extend the distance that this volume extends away from the camera in the Exponential Height Fog Actor. In the Details Panel, look for Volumetric Fog → View Distance.
Keep in mind that making this area larger will come with a performance impact. You may also need to adjust the value of the CVar “r.VolumetricFog.GridSizeZ”, which controls how many voxels are used in the Z direction (away from the camera). This does not change the distance, only how finely that distance is sliced.
For the emissive sphere, the glow effect you are seeing is entirely bloom, and is not related to Volumetric Fog. This means the effect is directly proportional to the number of bright pixels on screen, and their brightness. More dense fog will diminish this brightness, particularly as distance increases.
You can adjust the bloom intensity in the Post Process Volume, under Bloom → Intensity.
Please let us know if this helps.