earth night side

[yoann]

hello

i've been testing terragen for a week now to create an earth view from space, the result is really good but i've got a little problem when it's come to map a nightlight map to the dark side of the planet. I've try to use functions to get the luminace of the planet and many other things but i must admit that i'm a bit lost^^'
hope somebody can help and sorry for my bad english

[TheBadger]

Would like to see a test render showing the extent of your success so far.
It is hard to say what you should do because There is no indication here that you are even close. For example, Are you seeing any effect? Are you almost where you want to be?

If you are really close with a straight render in may be just a case of needing to out put an .exr. I found in some of my tests with luminance that it only seemed like I was getting bad results, but when I out put an .exr and tone mapped, I saw the light was all there and looking good.

It may also be that you are close to where you want to be with settings for luminance, but now need to play with other parameters.

We could post links to other threads (or you could search the forum;)) Or you you could just post a render of your best results so far, along with the settings numbers, or even just post the .tgd. Or we can just keep guessing... Its fun either way. 

By the way, your english reads just fine so far.

[yoann]

hello Thebadger.

I have to ask if i can post some render.

i'll try to be more clear ^^

What i want to do is to blend my 2 texture (diffuse color and nightlight) on the planet mesh based on the brightness of the planet surface ( have my diffuse color map were on the brightess part of the earth and in the shadow part the map with th city light.)

i've try to map the nightlight texture to the luminance of the surface layer, the result is visually good but the nightlight map affect all the surface of the planet. The best solution would be to mask the night texture based on the light luminance? or maybe i'm simply missing something with the setting's ^^' (and i've spend hour's to look for an answer in this forum )

[Dune]

I understand what you want to accomplish: normal colors on the side lit by sun, and night lights on the dark size of the earth. If the sun comes from a straight angle you might be able to 'split' the earth in half with a huge simple shape, but I guess you're looking for a way that 'reads the light' and thus acts as a mask. Maybe a 'get emitted color' or 'luminance to scalar' might be the way, but I've never done something like that.
But if you combine both, the normal colors will hardly be visible on the dark side, I'd say, and the night light will not be as obvious on the lit side. That isn't good enough?

[Tetra84]

what if you rendered two scenes - one with daylight, and another with night and used photoshop to blend them?