Celestia Forums

The Sun appears too big when rendered. This is most noticeable with total solar eclipses. With these eclipses, the sun peeks out from behind the moon when it should be completely hidden.

The sample eclipse shown below is the total solar eclipse that was visible from Hawaii in July, 1991. I chose this eclipse to demonstrate the problem because it was a total solar eclipse with a very long duration.

Hawaii Eclipse (Celestia URL)

Your problem is generated by two issues. One is the flare texture, which I do not use as you can see in the first picture below. The other is solar glow. If you change your field of view you will see that the moon actually covers the photosphere.

The second shot shows what I see with my flare texture. I created it to give a bit of a limb darkening effect, even though it's not that effective. It can me downloaded here:
http://clanmoran.net/celestia/images/flare.jpg

The third shot shows the default vs. my flare texture on the Sun.

I think the problem is the blurry edge that Celestia uses to render the sun and stars. buggs_moran demonstrates this in his images. The actual ball of the sun is hidden by the moon (as it is in my screenshot as well) but the fuzzy edge of the sun projects past the moon, giving the impression that the sun is too big.

A good fix for this would be to have the option to render this blurry edge. When this option is enabled the sun appears as it does now. When it is disabled the sun will have a sharp edge and eclipses will appear correctly.

bdm wrote:I think the problem is the blurry edge that Celestia uses to render the sun and stars. buggs_moran demonstrates this in his images. The actual ball of the sun is hidden by the moon (as it is in my screenshot as well) but the fuzzy edge of the sun projects past the moon, giving the impression that the sun is too big.

A good fix for this would be to have the option to render this blurry edge. When this option is enabled the sun appears as it does now. When it is disabled the sun will have a sharp edge and eclipses will appear correctly.

That "fuzzy edge" is actually the atmosphere. Disable the display atmospheres option, and you'll see what i mean.

PlutonianEmpire wrote:

bdm wrote:I think the problem is the blurry edge that Celestia uses to render the sun and stars. buggs_moran demonstrates this in his images. The actual ball of the sun is hidden by the moon (as it is in my screenshot as well) but the fuzzy edge of the sun projects past the moon, giving the impression that the sun is too big.

A good fix for this would be to have the option to render this blurry edge. When this option is enabled the sun appears as it does now. When it is disabled the sun will have a sharp edge and eclipses will appear correctly.

That "fuzzy edge" is actually the atmosphere. Disable the display atmospheres option, and you'll see what i mean.

It disables the fuzzy edge on the SUn all right. However, it also disables the Earth's atmosphere which gives a black sky. I think we need an option to disable star atmospheres and planet atmospheres separately.

Buggs:

Nice flare texture.

Is the G star jpg texture you use for the Sun one that you created? It looks different from the default. Is it also available for download?

Frank

fsgregs wrote:Buggs:

Nice flare texture.

Is the G star jpg texture you use for the Sun one that you created? It looks different from the default. Is it also available for download?

Frank

Sorry Frank, I missed this post. It is the default texture, gstar.jpg, as far as I know. I think it's the flare.jpg that changes it...

Hum I wonder if Chris working on the atmosphere will fix this. Instead of emulating the glare with a texture add an atmosphere to the star.