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Point Lights distance?

I am working on an EMS focused game. Something that has been eating at me is the lighting for the ambulance lightbar(s).. My prototype lightbar is just a blueprint I put together in the editor. I am using point lights as the actual lights. Each light on the bar, has a point light as a child. The lightbar is working pretty well and looks really nice (for a prototype) up close. The problem is that when i get a certain distance away from it (a rather short distance might I add), I can no longer see the point lights flashing, only the material on the "lights" changing. I can see the light on the ground from the point light, however up close the point light ITSELF is visible, which is what I want.

I've looked into LOD and haven't been able to fix it. To make this a bit easier to answer, How would I go about making a point light visible from extreme distances? Or if anyone has a better idea on what kind of light to use for a light bar I'll accept that too lol. Point lights make the most sense right now.

===== EDIT =====

That's a good thing to note Tim, thanks for pointing that out. Unfortunately that did not solve my issue. I've recorded a short clip so you can see what's happening


Product Version: UE 4.7
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asked May 13 '15 at 02:32 AM in Rendering

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2 answers: sort voted first

Hi BBrown,

To me this sounds like a bounds issue with the point light ignoring the bounds of the mesh it's casting a shadow against at a distance.

I've setup a simple rotating mesh and light BP and this is my result:

alt text

As you see in the image the point light ignores the mesh beyond certain distances. Is this what you're seeing as well?

If so, you'll just want to increase the bounds of your mesh that the light is being cast onto. You can go into the details panel for the meshes in your BP and find "Bounds Scale" to adjust this. The default value is 1.0. Adjust this until it's at the max distance you will need. I wouldn't go any higher than that because since the bounds are being increased this means that the mesh will be in the scene so long as it can be viewed at those distances. This can add potential performance issues.

Let me know if this was your issue. If not, can you post a video or images to demonstrate what you're seeing and I can take it from there.

Thank you!


pointlight.gif (506.5 kB)
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answered May 13 '15 at 01:41 PM

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Tim Hobson ♦♦ STAFF
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avatar image BBrown May 13 '15 at 07:41 PM

Please see the edit of the original post. I included a video link to show what is happening. Unfortunately your suggestion didn't work.

avatar image BBrown May 14 '15 at 03:30 PM
avatar image Tim Hobson ♦♦ STAFF May 14 '15 at 09:14 PM

Thanks for the video. I'll setup an example to test as soon as I'm able. It'll more than likely be early next week before I have the time though.

Thanks for your patience.

avatar image BBrown May 15 '15 at 04:33 AM

Great! thanks so much for helpin' out. Take your time, I understand you must be busy. I'm not goin' anywhere :P

avatar image BBrown May 20 '15 at 12:02 AM

Hey Tim, I don't mean to bug you. Just wanted to give a little bump and see how things are going. I'm REALLY stuck at this point. Everything I've tried has failed. I'm OCD when it comes to this haha so I've finally managed to force myself to work on other areas of the game until I hear back from you. I look forward to seeing what you come up with :)

avatar image Tim Hobson ♦♦ STAFF May 21 '15 at 02:34 PM

Unfortunately, I've not had the time to dig into this really this week. The 4.8 Preview releases and our custom licensee support has been taking a higher priority. I'll setup an example as soon as I'm able, it just takes a little more time that I have at the moment.

Thanks for your patience.

avatar image BBrown May 21 '15 at 06:52 PM

No problem, that is completely understandable :)

avatar image Tim Hobson ♦♦ STAFF May 27 '15 at 04:19 PM

Hey, I was able to look at this a little more this morning and set up an example that I could test.

It looks like there is a combination of things that could be going on here. Since I don't have access to your specific settings this may be guess work on a few things.

Ultimately, a lot of it comes down to the post process, the light attenuation radius, and light cone angle.

Initially I turned off the post process (disabled Bloom, lens flare, and set the auto exposure to min/max of 1.0). With this off I can see if it's a light distance issue or if there are other issue to factor in.

I set the light brightness to 7,500,000 and unchecked "use Inverse Squared falloff". Outer Cone Angle to 25. Attenuation Radius to 150.

While this may seem like a high value, the light is inside another mesh with a translucent material. From a far distance I could still see the light working so I knew this wouldn't be an a bounds issue for the light.

I then adjusted the post process Bloom and Lens Flare back to 1.0 each (default values).

Video Demonstration of my setup: https://www.dropbox.com/s/v5zcevgnfkay6z6/Lightbar.mp4?dl=0

Overall, adjusting the cone angle and the radius should give you better results for the further distances. This will directly affect how the post process reacts when closer to the lights though. It may take some tweaking to get things just right.

I hope this helps.


avatar image BBrown May 28 '15 at 01:06 AM

Yeah I'll give this a try and see how things turn out. It looks like this will be the best solution. Thanks so much for taking the time to help me with this :)

avatar image Tim Hobson ♦♦ STAFF May 28 '15 at 06:09 PM

No problem at all. :)

Let me know if anything comes up and I'll be happy to look into it more when I can.

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I had a similar issue and one of the Tim's points fixed it for me. My light was recessed in a cone I used for decoration. As I approached the light it would seem to shut off. Pulling the light farther out of the cone made it work at any distance. Hope this helps someone!

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answered Sep 16 '17 at 12:49 AM

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