How do I add a ground horizon of a chosen color to the skysphere?

I would like to know how to modify the sky sphere to potentially fix the problem shown below:

When viewed from high above, you can definitely see the edge of the level (somewhat exaggerated here so it is clear what I am talking about). Is there a way to change the skysphere lower half (e.g. “where the ground would be”) to be a chosen color (in this case, the color of the ground)? I would like to make the part of the sky that appears bright pink to be the color of the ground.

I have found a way that works that yields the desired effect AND still lets you use the Unreal Skysphere. Just make what I call a “ground sphere” within it, with a transparent top half. I have made an “inverse sphere” in Blender that can work as a “ground sphere”. I have made this available to the public here: [SkySphere][1]
[1]: Free Skysphere - Google Drive

  1. Download and import the .fbx skysphere that I made in the link above into Unreal Engine (or create your own inverse sphere)
  2. Download the .png image at that link: GroundSphereWhite.png, and import it into Unreal Engine, or make your own such image (transparent top half, white bottom half).
  3. Make a material in Unreal Engine and edit it:

a. Make a material in Unreal Engine and edit it: Change the material settings to Masked

b. Change the lighting setting of the material to not lit

c. Drag the GroundSphereWhite imported image in to the blueprint

d. Multiply the image top pin by a color (const 3 vector)

e. Promote that color to a parameter, and name it color

f. Create a pin from the result of that into the emissive box
  1. Make a new instance of the material, and name it something appropriate for the level (e.g. M_Mars_Background_Ground)
  2. Drag the imported skysphere into your level, and apply your newly created material instance. You might need to rotate the sphere some to get it in the right position (not sure why this happened to me).
  3. Set the new skysphere’s setting to not cast shadows (uncheck the box - cast shadows)
  4. Adjust the color parameter of your instance material (e.g. M_Mars_Background_Ground) until it matches nicely with the ground of the level.

Now, hopefully you have a landscape that looks like it goes on and on, without being able to see the square edges of the level because it blends in with the new background! You may need to add something to block the reflection from the sun in the background if your ground is shiny, or make the ground not shiny (roughness = 1, and / or specular = 0).

Hope this helps! I might make a YouTube tutorial on it later, especially if someone here requests it.

An alternate way (which I used on Venus for Planetary Settlers) is to make very large planes, make a color that matches the ground color, and add 4 such planes on the outskirts of the level. This method seems to work better on levels that have significant amounts of fog. However, if there isn’t fog in the level, my main way, posted above seems to work better. I have used the other (accepted answer) “ground sphere” method to fix most of my levels in Planetary Settlers, which that update should be out by 7/1/2019.

In fact, I released the update now, this shows the before and after: Steam :: Planetary Settlers :: New Horizons Update

thank you alot