Soft lights through window

Hi! I use UE4 since few weeks, but lighting for me is really really hard piece of cake which I can’t handle even with documentation which is basic and only useful on beginning - I could even pay for some advanced lightings e-books/videos. I don’t say that documentation is bad (it’s great!), I learned there a lof and without this I couldn’t do anything.

So I trying to make a basic scene (don’t have this scene on current PC so I can’t show you what I mean, sorry) and I want to spread out my lights which came through window - in other words, I want to blur my shadows somehow. Basic setup with Directional Light (focused on windows) + Sky light + Atmospheric Fog gives hard shadows which is boring. Here is nice example which I found right now:

Someone have any idea how to achieve something like this?

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That is indirect light coming through the window so there are a couple of ways to imitate that. You can use a white plane directed at the window(outside the building) and an intense spotlight pointed at the plane to get the bounced lighting, or use a stationary skylight which isnt sufficient for interiors most of the time…or you can use a combination of both.

Well, thanks for answer but maybe is other way to do that? I saw a lot of great works on Polycount last time, for example this:[ue4]

I don’t think OP used your method to achieve this result. He have interior and exteriors and placing white plane mesh in front of window and spot light directed on this plane doesn’t make sense.

Well, you only get softshadows like that from indirect lighting, so windows where the sun isn’t directly shining in, that’s what’s going on in that polycount thread, the lighting is just light from outside bleeding in through the window, and that’s what’s happening with the reference image. You can still use a white plane and spot light to add more like or alter the results you are getting, and just hide the mesh, there’s a great example of that with the content examples on the market place from Koola.

I understand now … a little. I spent this day trying to solve this problem, but without good result. I have made what you say, white plane outside the building, directional light which was directed in different direction than windows is placed and spotlight directed to white plane with different intensity just to test it, and it doesn’t work proper (it depends on intensity light value which I choose, but any of this works at least good). Light bounce doesn’t work for me in this case. Floor is dark (not black, but dark) and I ending usualy with basic lighting which looks bad.

Another thing which I trying to solve is that if I place white plane outside the building and window hole, I will close holes where Directional Light comes into the room. Seriously, I don’t know how this method could work in this case, when I have interior + exterior scene.

This is what I get. Plane is white but it change color to black somehow after bake, spotlight is directed to plane (intensity 6)

Still working on it, but before I will back to learning UE4 i have question about grayed out (not active) options in UE editor.

In this topic i found similar problem.


So I want to use Light Source Angle and incrase value of this, but i can’t do anything even if I change from stationary to static.

Here is an example for you.

This is how you need to set up the plane and spot light;

And this is the result you get inside;

This is a larger environment than a room with a normal sized window but you get the idea. You can increase the spotlight’s intensity and indirect lighting intensity to increase the amount of light that bounces through the windows. Let us know if you have changed any lightmass settings in World Settings as well since they also affect the outcome.

I really appreciate your help, really, but this method doesn’t work for me :frowning:

Maybe I’m dumb, but I made the same thing you do several time. One of example is few comments back in this thread.
Several tests:

  • Spotlight light intensity to 5000 and Indirect Light Intensity 5.0 - scene goes clear white with some shadows on edges of geoemtry
  • Spotlight light intensity to 2000 and Indirect Light Intensity 5.0 - scene goes gray, but there is still no big differences to previous one
  • Spotlight light intensity to 200 and Indirect Light Intensity 5.0 - nope, still looks bad (screen is bellow)

Some other facts:

  • lightmap is ok (lightmap density is green)
  • don’t have any UV errors after baking

Everything looks similar to example which I show earlier.

Can you create a blank project with no starter content, and then setup this same scene in it please? And then upload the project to dropbox or whatever you use so that we can take a look. If it’s ok with you of course.

Finally I made something which looks … not great, but good.
Under DirectionalLight -> Lightmass there is an greyed out option (Light Source Angle) which is set default to 1. I couldn’t change value of this because it’s not active even if directional light is set to static (probably bug, can’t tell), but by accident by pressing RMB on number area I realize that I can paste something. I wrote 20 in notepad (well, because it was open :slight_smile: ), then copied and paste there - it works. Here is result after 12h of battle ;< :

Still need to understand plane method because in this case DirectionalLight is directed on window. Tomorrow I will send link to scene.

I decided to go back to this thread just to tell that this method (with plane bouncing light) not working for me and I don’t know exactly why. Quite everything is set to default.

I don’t understand few things:

  • Why my scene after proper set scene up is so bright, more than in example made by Jacky?
  • Spot light power set to 5000 is large value?

This happen on every new scene which I create.

Here is my scene:

You need to run Test_scene map file to check this scene.

In the previous post you were trying a spotlight hitting the window but now are talking about the directional light having more of an effect.

It seems in the most recent post you are showing the directional light shining directly through the window with soft shadows which is a different effect altogether.

To isolate the issue, I would turn off the directional light while testing this. Only use one spotlight that is directed at the window pane. Double check the number of bounces you have enabled in the world settings under lightmass.

Also try setting the spotlight to static as well if you have not already.

So i checked the project and here are the problems:

  • You didnt have a lightmass importance volume covering the building.
  • In World Settings indirect lighting smoothness was set to 7, which smooths out all the shadows.
  • The spotlight’s indirect lighting intensity was set to 5, which was a lot when you combine that with 7 indirect lighting smoothness.

Also i dont suggest importing the building like you did in that project. It is safer to bring the building wall by wall, each wall being a closed mesh. This way you wont have any strange issues in the long run if you happen to use dynamic lighting at some point.

I’m going to upload the project in a while and update this post. Then you can download it and compare every parameter with the old one to see how to achieve the same effect.


Here is the link; Dropbox - Test_Project_2.rar - Simplify your life

And here are two screenshots with the directional light on and off, spotlight on in both.

But what to make when I go outside building? I will see a white plane :slight_smile:

In this situation, is a correct way just to add spotlight at window in direction to look in room ? Like in picture?

And I have destructible window.

I test this - and this is good.

You should be able to set the plane to be hidden in game and it will still affect the static lighting rebuild. There is also a setting called ‘cast hidden shadow’ that can be used for similar situations with dynamic lighting but I do not think you will need it for a static bounce light card since technically you aren’t relying on any dynamic shadowing.

But for now, everything works great without white plane :smiley:

What is difference between light bounc from white plane and direct light like on my picture?

The only difference is visual style. Its up to you.

You might want to use a tool specifically made for this. You put it beside windows when you want soft light coming through from exterior light.