UEFN Cubemap Generator
Turn six screenshots of your level into a cubemap for the Sky Light. UEFN has no Scene Capture Cube, so this does the same job without opening Unreal Engine. Your images are not uploaded anywhere.
Front
Right
Back
Left
Up
Down
Six screenshots, one spot
Stand still, take Front, then turn right for Right, Back and Left. Face Front again and look straight up, then straight down.
Position each image
Drag an image to move it inside its frame. Scroll or use the slider to zoom. Whatever is outside the frame is cropped.
Preview
Drag to look around
Your cubemap appears here once you add a screenshot
Lights
Adds a light source brighter than white. Click a bright window, doorway or lamp to turn it into a real light, or any other spot to paint a glow there.
Brings the six sides to the same brightness. Use it when some screenshots came out lighter or darker.
Also evens out the tint between sides. Leave at 0% to keep each screenshot's own colours.
Evens out brightness and colour across each edge and keeps the image sharp. Higher values reach further into each side.
Softens the whole cubemap for ambient light. Use 0% to keep the screenshots sharp.
File size
Add at least one side to download. Images stay on your computer.
How to use it
From screenshots to a lit level in four steps.
- 1
Take six screenshots
In UEFN, move the viewport camera to the spot the light should come from and hide the editor icons. Take one screenshot facing Front, then turn right 90° for Right, Back and Left. Face Front again and take one looking straight up and one straight down. For sides that line up exactly, set the viewport Field of View to 121 for 16:9 screenshots; the tool shows the value for other shapes. Or shoot through a Cine Camera with the settings below.
- 2
Drop them in
Put each screenshot in the slot with the matching side. Any size and any aspect ratio works. Drag an image to position it in its square frame and zoom if you need to. What is outside the frame is cropped.
- 3
Blend and download
Check the result in the preview. Match brightness evens out screenshots with different exposure, Match colour evens out their tint, Seam blend smooths the edges while keeping the image sharp, and Blur softens everything for ambient light. Add light puts a light source brighter than white into the cubemap: click a bright window, doorway or lamp in the preview to turn it into a real light, or any other spot to paint a glow, then set its intensity, size, softness and colour. Then download the .hdr file.
- 4
Use it in the Sky Light
Import the .hdr file into your UEFN project, where it becomes a Texture Cube. On the Sky Light, set Source Type to SLS Specified Cubemap and pick the texture in Cubemap. Use Intensity for brightness and Source Cubemap Angle to turn it.
Camera settings for exact edges
Place a Cine Camera Actor and take the six screenshots through it. In its Details panel, set the two values marked below and leave every other value as it is.
| Setting | Value |
|---|---|
| Set these two values | |
| Current Focal LengthThe default is 35.0. The new value is half the Sensor Height, so each screenshot is exactly 90° tall. | 6.6825 |
| Current ApertureThe default is 2.8. The new value keeps everything in focus. | 22.0 |
| Leave as is · Filmback | |
| Filmback | 16:9 Digital Film |
| Sensor Width | 23.76 mm |
| Sensor Height | 13.365 mm |
| Sensor Horizontal Offset | 0.0 mm |
| Sensor Vertical Offset | 0.0 mm |
| Sensor Aspect Ratio | 1.777778 |
| Leave as is · Lens Settings | |
| Lens Settings | Universal Zoom |
| Min Focal Length | 4.0 mm |
| Max Focal Length | 1000.0 mm |
| Min FStop | 1.2 |
| Max FStop | 22.0 |
| Diaphragm Blade Count | 7 |
| Leave as is · Focus | |
| Focus Settings | Default |
| Current Focus Distance | 100000.0 |
Leave the images where they land
The tool crops the centre square of each screenshot, and with these settings that square is exactly one side of the cube. Do not drag or zoom.
Rotate, do not move
Keep the camera in the same place for all six shots. Use yaw 0, 90, 180 and 270 for Front, Right, Back and Left, then pitch 90 up and 90 down from the Front rotation.
Another filmback
Set Current Focal Length to the Sensor Height divided by 2.
Black bars at the top and bottom
Set Sensor Width to the same value as Sensor Height. The picture becomes square and the bars move to the sides, where they are cropped.
About the cubemap generator
A Sky Light can take its light from a cubemap instead of the sky. In Unreal Engine you would capture that cubemap with a Scene Capture Cube, which UEFN does not have. This tool builds the cubemap from ordinary screenshots instead.
It is made for fake ambient light. The cubemap carries the colours around the camera: sky colour from above, ground colour from below, and the tones of the walls or landscape on each side. The sides do not need to line up perfectly, because the blur blends them together. For a sharp cubemap, capture at the Field of View the tool suggests and use the matching and seam sliders instead of blur.
Tips for a cleaner result: keep the camera in the same spot for all six shots, hide editor icons and the grid, and keep the exposure the same between shots so no side comes out brighter than the others.
Screenshots store colour but not real brightness, so set how strong the light is with the Sky Light's Intensity. If a side looks turned in the preview, use the rotate button on that image.
The file is built on your device as a Radiance .hdr long-lat image. Gelos Games is not affiliated with Epic Games.