Holes in model

Look at this:
http://bildr.no/thumb/129645.jpeg

Why does these black, or dark spots appear? This is actually a flat area, but it seems like something has gone wrong. How do I fix it? I think it appeared after I used Subsurf. It has happened many times.

Maybe this have been answered before, but I didn’t find anything.

Not sure how to explain it, but it has to do with normals (google it for more info).

Selecting all and hitting ctrl-n will fix those dark areas. Depending on the area and the way its “built”, doing this may just create those dark areas in other areas as well.

Thanks! That’s great!

Normals have to do with texturing. Every face has an outside and an inside. It’s invisible from one side whereas the texture is supposed to go on the other side. At times things can get screwey. If you want a clear view of which faces are inversed, you can view your model in UVfaceselect, then back to edit mode, select the faces in question and flipnormals using the “W” dropdownmenu. Same thing Housearrest said, just that now you know what you’re doing.

if you have a compound object ( an object with different parts that intersect each other ) you need to position the parts so they are not interesecting before doing ctrl N ( recalculate normals outside ), then return them to the correct positions.