Shadows along edges of mesh in 3D View I have recently started using blender and one of the models I'm working on has dark shadows along edges. I started this model from scratch. I can't remember them being there when I first started the model, but I had trouble joining areas together and think I've pressed something I shouldn't have. However, there are so many options I'm not sure what I did.

Here is an image of what I mean


The one on the left has the shadow. As a test I started a new model, which is on the right in the image, and as you can see it doesn't have any shadows.

Also, occluded vertices partially show through the model. Occlusion doesn't work properly.


In orthogonal view small darkened triangles appear along the the edges. 


I don't really want to start the model again from scratch so any ideas on how to remove this shadow would be great. Thanks.
The issue you are calling "shadow along edges" is more generally known as z-fighting   (if you want to search for more info on the topic).

In our manual we document this problem:


  A large clipping range will allow you to see both near and far objects, but reduces the depth precision.


To resolve, in the view settings you need to reduce clipping range.


set the Clip Start as high as you can before near geometry disappears.
set the Clip End as low as you can before far geometry disappears.


The Camera has its own start/end settings so you may want to adjust that too.

Note that typically you won't need to tweak this value often, it just needs to match the scene scale you use

A range between 0.1 -> 100.0 is fine if more model has dimensions of ~0.5 -> ~50 blender-units.

Note that some graphics cards cards suffer from this problem more than others because they use a lower bit-depth for their z-buffer.