Weird Black "Shadows" On Rendered Image I'm getting these weird black shadows on my rendered image of this mailbox I'm making. Here's a link to the file and a link to YouTube so you can see what's going on.



I was able to mess with the normals and removed all doubles and this is what I was able to come up with. That will still not go away unless I change the texture to diffuse, and it's not a shadow: I've moved my lights and camera trying to see but it wasn't.

EDIT:

So did all that stuff and still no luck, It did make it look better but on the angle that I want for the pic there is still an area. I have found that if I rotate the camera there are certain areas where this "shadow" does not occur. I also checked to see if maybe the letters or the top of the mailbox was casting a shadow in some way, but that was not. I also moved my light sources around, took away the floor, and added more objects around to see if it would work. Well it still has that unsightly shadow, although it does look better I'm just surprised there is no way to get rid of that black shadow that I know of.

Here is a pic of my current progress



It's kind of hard to see in that pic but at the bottom right corner there is still a weird shadow. Also I found if I take off the top there is an unsightly shadow on the top of the main mailbox mesh. And this is after I deleted duplicates and checked my normals, etc.
A lot of your normals are facing inwards.  You probably can't see this because backface culling is disabled by default.  I always keep it activated so I can see these problems right away.  Here's what it looks like with Backface Culling enabled.



You can view the normals using the following setting.  

 

You can flip them with the following tool in Edit mode.



I also use remove doubles because there were many vertices that were overlapping which were not attached to each other.

The door is partially attached to the rest of the mail-box at the bottom which makes the polygon flow difficult to work with.  

Also, there is a shelf inside the model which is attached to the outer polygons, this may be intentional but has the same effect as interior faces: it causes rendering artifacts and was the biggest problem here.



Cycles cannot handle super low-poly models very well.  Basically triangles become very dark and visible at areas where the lights hit them at glancing angles.  Adding more geometry, lights and an HDR texture can help with this.  

I used inset on the top piece and some loop cuts along the rim.





The main box and the door have a Bevel Modifier attached and set to 'Angle'.

I applied the Solidify modifier on the door latch/hook thing and added inset and loop cuts to it as well as a sub-surface modifier to make the edges more crisp.





Here's the .blend http://www.pasteall.org/blend/34426