Sean, I love the image of the Apennines and the Apollo 15 landing site!

Thanks for posting some new animations to enjoy. Might be something outside your workflow, though it might look neat to try and add in some opposition effect if you're looking in the direction opposite the sun. It's hard for me to find an example of this (from orbit) for the moon, so I'll substitute one from the Hyabusa 2 spacecraft instead:

http://www.hayabusa2.jaxa.jp/en/topics/201...TD1R1A_W1movie/

Thanks, I've noticed this quite a bit when working with ISS sequences.

Indeed it's important on the Earth as well, where at least the core of this effect might be modeled with a simple phase function. I like your last animation posted above with pretty convincing changing shadows at sunrise.

This is the heiligenschein effect which is caused by very tiny glass beads in the regolith. The glass beads are created by micrometeorite bombardment. The same of course is seen in Apollo orbital and EVA photos. The Hapke parameters could be reversed to create the heiligenschein effect, based in solar incidence angle versus emission angle.

I had thought heiligenschein was mainly associated with dewy grass on Earth - interesting that this also applies to glass beads on the moon.

I think a more general opposition surge phenemenon can happen with a greater variety of compositions, including dry grass on Earth or dry dust as well.

Yes the Hapke terms (related to the notion of bi-directional reflectance distribution function - BRDF, or anisotropic reflectance factor - ARF) would be a more complete treatment. A quick approach might be a simple ARF using phase angle only that could be a correction to be multiplied by the original image.

Dewy grass is the most obvious. Yet of course, other things also can create heiligenschein.

Sean's works are amazing to watch. If he does decide to try anything, I agree that a simple ARF method would be the way to go, as it should be more than good enough to simulate the lunar heiligenschein effect. I don't think that he needs to be precise about it either. Doing calculations for a simple sphere, ignoring the actual terrain, probably would suffice nicely.

Yet even slicker would be if Sean would add a global calibrated WAC color image overlay. The WAC filter numbers which best represent RGB are filters 7, 4 and 3 (listed in order of RGB). Following is a chart I made which shows the bandpasses of the WAC filters. As you can see, the blue filter #4 really is violet. I always end up having to perform a bit of a hue shift for blue when creating color WAC images in order to more accurately simulate what the human eye would see.

New release of LRO data for 3D imaging CGI Moon kit, surely to come in handy for all that free time i don't have

Too much data! Not enough time!

Thanks for the input guys... I'll be sure to reference on my next trip to the Moon.

Funny little mnemonic in the terminology: Heiligenschein is German for "holy shine" and it is noticeable when you see the shadow of your own head in dewy grass and your head's shadow appears to be surrounded with a glowing halo, hence the angelic association. Of course, in that circumstance, your head itself always blocks out what would be the most intense location of the effect.

I'm hoping for good skies this year when Uranus is in opposition to see if I can use this to get a picture of Uranus' rings – fingers crossed. I'm pretty sure in that case I don't have to worry about the shadow of my head, or the Earth.