Celestia Forums

I have two ideas to help Celestia emulate reality.

1) As an object gets farther from a light sources, it gets dimmer. This already happens in double systems, so I don't see why it can't be done in single systems. Therefore we don't have objects 0.9 light years from Sol all happy and shining bright, lol.

2) Have the position of the terminator relative to the distance of the light sources.


The yellow line across the planet is where Celestia draws the terminator.
The red line is where the terminator should be.

And here's a pic of flying over the planet, and seeing it as very dark, while the sun shines brightly just above the horizon.

Good idea! I hadn't thought of that...

Hungry4info wrote:I have two ideas to help Celestia emulate reality.

1) As an object gets farther from a light sources, it gets dimmer. This already happens in double systems, so I don't see why it can't be done in single systems. Therefore we don't have objects 0.9 light years from Sol all happy and shining bright, lol.

This issue has been discussed at length before. The human eye operates very well with a wide range of light intensities. While the brightness of sunlight at Pluto is only 1/1000 of what it is at Earth, this is still about as bright as the inside of a house lit by ordinary indoor lighting. Thus, we'd be able to see Pluto quite well, and what Celestia shows isn't unrealistic. You're right that there shouldn't be much to see at 0.9 light years, but since all of the solar system objects we know about are well lit, I don't think we urgently need a fix.

2) Have the position of the terminator relative to the distance of the light sources.

Now this is something that I would like to fix in the near future. As you noticed, Celestia treats all light sources as points. Some simple modifications to Celestia's surface shaders (atmospheres are considerably trickier) could approximate area light sources.

--Chris

chris wrote:The human eye operates very well with a wide range of light intensities. While the brightness of sunlight at Pluto is only 1/1000 of what it is at Earth, this is still about as bright as the inside of a house lit by ordinary indoor lighting. Thus, we'd be able to see Pluto quite well, and what Celestia shows isn't unrealistic.

Ah, I didn't know about that. Thank you.

One would want to strive for an (optional) interface that responds to changing dynamic ranges more or less in the same manner the human eye and brain does. As far as I've understood this is in the workings.

So umm... now that much time has passed. I ask, is now a good time to address this situation?

Hungry4info wrote:So umm... now that much time has passed. I ask, is now a good time to address this situation?

Not until after 1.5.0 is done . . .

Dirkpitt has worked on modifying Celestia for high dynamic range rendering; his code can automatically adjust the 'exposure' to approximate the human eye's response to changing light levels.

As for modifying the position of the terminator based on light source distance, no work has begun. It's a task that requires a lot of 3D graphics know-how and a lot of adjustments to Celestia's shaders, so I don't think it will be undertaken for some time.

--Chris