Shadow weirdness?

[Monkeyfarm]

Any idea what causes this and how to not have it happen? Note red circles.
http://www2.zbrushcentral.com/zbc_uploads/user_image-1042415222scb.jpg

[Muvlo]

Pixols store both Z and depth info. But when you add a new object to the canvas, whatever was already there is overwritten. The areas where your shadow disappeared are a leg which is covered by the other leg and an arm, which is covered by the torso.

Perhaps you could create another layer and just add those parts to create the shadow. Or draw the shadow in yourself.

[EDIT]
LOL, looks like I answered the question to a completely different kind of problem! :o Good thing Aurick is here!! :)

[aurick]

Sorry, Muvlo. This one got you. ;)

The problem has to do with the number of rays. When you have ZMode active in the Shadow palette, you get the most accurate possible shadows. BUT with only 1 ray selected, ZBrush doesn't have very many options available to it for creating shadows and these types of artifacts occur.

If you increase the number of rays, the holes will disappear. You will also most likely want to decrease the Aperture as you increase the Ray count so that you keep clearly visible shadows (a high number of rays with a high aperture will cause the shadow to pretty much disappear because the ray edges are too soft).

Use 1 ray when you're setting up your lighting so that you can make adjustments without having to wait for long renders. You don't care much about artifacts when doing setup lighting -- all you care about is that you get things layed out right. Once the setup is the way that you want it, increase your rays and decrease your aperture to suit your needs.

The bottom line: the more rays you have, the more accurate your shadows will become -- at the price of longer renders.

[Jaycephus]

Aurick, thanks for the tip!

:qu: Do you have a rough number for the minimum rays and the ideal aperature setting for a high-quality, realistic shadow? Thanks,