Improve atmosphere

[pjcozzi]

CC @tfili

• Show atmosphere on the globe, not just the sky
• Maybe show atmosphere on objects

Reading (old to new)

• Rendering Outdoor Light Scattering in Real Time - old, but good intro material
• Accurate Atmospheric Scattering in GPU Gems 2 - what Cesium does now (sky only). Perhaps do ground atmosphere as a separate pass over the central body?
• Real-Time Rendering of Planets with Atmospheres - too big to stream?
• Precomputed Atmospheric Scattering
• An Approximation to the Chapman Grazing-Incidence Function for Atmospheric Scattering in GPU Pro 3

Lots of stuff on vterrain.org.

[hpinkos]

Side note: The moon currently obstructs the atmosphere

[hpinkos]

Also, the atmosphere doesn't render on some mobile devices. Reported on the forum: https://groups.google.com/forum/#!topic/cesium-dev/Z3KJnMCkSSc

[mramato]

#3141 has weblreport for my phone (which doesn't show atmosphere). My Nexus 9 tablet shows the atmosphere fine.

[jmgomezpoveda]

I have realised of the same issue as #1064 (comment) looking at the globe from afar. When the Moon is behind the Earth, the Moon is rendered below the Earth, but on top of the atmosphere.

[pjm4]

@jmgomezpoveda et al you can see this issue, where the moon appears in front of the atmosphere, but behind the earth, more pronounced when the size of the moon is increased with the following code snippet:

var radius = Cesium.Math.LUNAR_RADIUS * 10;
viewer.scene.moon = new Cesium.Moon({
    ellipsoid : new Cesium.Ellipsoid(radius, radius, radius)
});

[pjcozzi]

• Tutorial series on atmosphere

[pjcozzi]

• Hot off the press: Precomputed Atmospheric Scattering: a New Implementation - a new implementation of Eric Bruneton's Precomputed Atmospheric Scattering paper.

[pjcozzi]

• Follow up to the GPU Pro 3 chapter: Followup to Atmospheric Scattering—Part 1

[pjcozzi]

CC ground atmosphere, #6877

[ggetz]

Closing this after recent atmosphere improvements we've made. Going forward, we'll track specific enhancement ideas in new issues.