Earth Shadow problem


I’ve started to use blender a few months ago and some of the projects i’m doing involve rendering planets. The problem i have is that on every planet i made, the dark side of the planet is bigger than the day side. I’ve tried different kinds of lamps, lamps arrays , changed the shaders values, and nothing, always have the same problem.

So what i want to do is to get the terminator to pass trough the red dashed line insted on passing where it passes. Can anyone please give me some insight on how to solve this problem?

You could move the light maybe? Would move the shadow too…

//The M.h.p.e.

well, that would be enough for a still image, but since i’m planning on doing an animation of with the Earth rotating around itself and around the Sun, i’d rather not move the lamp if possible…

Anyway, thank you!

Hmm…well. All spheres in Blender behave that way. I recon the real life Earth
reacts the same way to light, but not sure…

//The M.h.p.e.

Hello Guys,

I have seen jorgehumberto’s problem yesterday, and we tried several kinds of lamps (area, hemi, lamp, sun, spot etc) and if i am not mistaken, the image above was produced with a Sun lamp (which i thought it would emit paralel rays, but i was informed that that is not the case, so this effect is to be expected…).

Try to increase the distance of the Sun Lamp and increase it’s intensity (to compensate, if needed)


Mess around with the Bias settings, they affect the extention of the terminator

(Actually, these suggestions were made by rcas :wink: )

The M.h.p.e.: 50% of the Earth is lit by the Sun (dayside), and the other 50% is in darkness (night)…If that was not the case, in an equinox the duration of the day wouldn’t be equal to the duration of night (each with 12 hours, give or take a minute)…You can see in the image above that both of Earth’s poles are in total darkness during a rotation of the Earth, and that cannot happen to both simultaneously ;)…

off-topic: The M.h.p.e., your “Starry Night” is awesome :smiley:


Bellboy: About the earth thing: Yea, you’re right. Man, what a brainfart I
had there… :slight_smile:
Guess, that in real life the line is blurred just like here, only that the distance
makes the area of “mid shadow” veeery tiny. So he just needs to move it a
couple of unimaginablelions away, and turn the strength waay up. :wink:

  • hmm… not sure if this problem can be solved that way. Toon shading maybe?

off-topic: Thanks, Bellboy! :slight_smile:
//The M.h.p.e.

Making an area light that is close to the same size as the planet should do what you want, although I thought the sun lamp would be parallel too.

Also, I assume you remember that the axis of the Earth is tilted and the vertical axis was just to illustrate the problem better right? :wink:

You might also need to adjust the softness to get an appropriate dusk effect on the temperate/polar regions.

Well, i tried to bump all the way up the intensity of the Sun lamp to 10, guess what? The terminator is where it should be…then in steps i diminished the intensity and what happens is that the darkness area of the terminator extends…

About the softness of the limit, that is realistic and thus a desired effect…except for the location of the terminator, everything’s fine in the picture above…(well almost :))

Another suggestion by rcas:

Use hemi light on the side of the actual side of Sun and use a Sun lamp on the other side (behind Earth) with negative turned on…

By the way, jorgehumberto knows that the Earth axis is tilted, don’t worry

As everything else in CG, fake as much as possible, it doesn’t need to be an accurate Sun light, if you can fake it really nice it will be as good as a physics simulation.

So, here’s a dummy file I did just with a sphere and Spot lights, nothing fancy, just enough to keep you guys busy :wink: .

Earth Light Simulation

– Rui –

Ok, jorgehumberto and me have been trying an idea we had…using the fact that a sun lamp with maximum intensity gives the desired terminator, so the trick was to make a sun lamp with “Only Shadow” turned on and intensity 10 to give the shadow on the Earth and a second sun lamp with “Ray Shadow” turned off and a lower intensity, to iluminate the Earth…

Anyway, many thanks for your replies, specially rcas for beeing extremely helpful :smiley:

well, after a little brain storm with bellboy, we found a solution:

A little better don’t you think? did as Bellboy told and just tweeked the shaders a little bit… also changed the earth texture…

now just have to add clouds and do some more tweeking and hope i can get the result i want

Anyway, thanks to all for your help.

btw: The M.h.p.e., Starry Night is great!!!