Hi, in this video we’ll see how to set a
volume material to create a physical sky. First of all press Ctrl+J to open the
color management. Click on add color space and go to the LUT file name folder icon. Choose the slogm LUT given with the project and validate by pressing ok. Then set the LUT on your 3d view. In the project there are two one meter wide spheres. If we zoom out we can see that those two spheres are on another big sphere. Actually this big blue sphere has the diameter of the earth at real scale. In other words the sphere is 6,371 kilometers wide. There is another big sphere here in the back.
The Sun at real scale As you see it’s at 149 million kilometers from the earth. There is just one light in the scene. It’s a physical sphere light that matches perfectly the size of the Sun. It has a radius of 695.7 kilometers, but in fact the light is a thousand times bigger because it’s parented to a locator which has a scale value of 1000. OK let’s focus back to the earth and change the display mode to progressive rendering. Unhide this volume by pressing Shift+H. This volume surface will act as the atmosphere of the earth. The scale of this volume is slightly bigger than the earth. Let’s go back to the little spheres on the surface of the earth. The Sun is parented to an animated locator. When you scrub the timeline the Sun rotates around the earth. Select the picker tool and click the
middle mouse button on the volume to select the volume material. I textured the density multiply input of the material. The result of a constant color is
multiplied two times by 0.001 to have an extremely low value for the density. As we deal with a giant volume, we have to set an extremely low density value otherwise the light would be occluded. OK, first set the Sun at the zenith by
scrubbing the timeline to frame 150. Then edit the scattering color to define the overall color of the sky. Scrub down in the timeline to have the
Sun near the horizon. Edit the absorption and set a blue color. The volume will then absorb blue colors from the lights and you will be able to define a nice orange color like in a sunrise. Add some forward scattering for a more convincing effect. Switch to the image view and scrub the
timeline from frame 0 to frame 300 to have a full-day physical sky rendering. You can notice in the chrome sphere how
the forward scattering makes a nice sunset effect. Select the moon render image scrub the
timeline and see how the Sun rotation. affects the sky and the moon Here is a full render of the animation done
in this project. Have fun with the setup and see you next
time, bye !