Maya MR question

Hi, first I'm self-taught maya and apologize if I stumble a bit with the terminology or if this is a stupid question.

I've been trying to bake sculpted prim textures with mental ray via the method shown in steps 1-5 here:
http://www.game-artist.net/forums/vbarticles.php?do=article&articleid=17

This will work to a point - it tends to leave black lines at certain areas - the seams/poles of the NURBS shape(which alone aren't that big of a problem to edit out), and (guessing here) in areas where I have control vertices too close to one another? Also I've had some textures come out entirely black... I've tried "edit NURBS" > "Reverse surface direction" assuming these ones were inside out but that hasn't helped.

Here is a picture of the "black lines" I'm experiencing:
http://www.putfile.com/pic.php?img=6786022

I've been manually removing the unwanted black seams and lines in photoshop, but am assuming there is a better way to do this...

Welcome to PITA Land, otherwise known as Mental Ray. Getting good results with MR can take a really long time.

If you can afford it, I'd recommend using Turtle. 99% of your problems would disappear instantly. And you'd hardly need to do any retouching in Photoshop at all. In fact, now that I think about it, I can only remember having to do any serious retouching once in the whole time I've been using Turtle, and that was on a bake of a very shiny, very oddly shaped surface, that really should have had far more isoparms in it than are allowable for sculpties.

Anyway, one thing I might suggest is altering your modeling technique a little to hide poles wherever possible. Remember, there's no reason that geometry has to be uniform. Go with what works best for the task at hand, not necessarily with what looks neatest in wireframe.

I notice, for example, you've got a pole on the side of the arm of your couch. What I would do is build the arm perpendicular to how you've got it, so the poles are on the top and bottom instead of on the sides. The bottom one will be automatically out of the way, and the top one can then be hidden underneath the back cushion. And speaking of the back cushion, its poles can be moved down to hide inside the arms. By making these simple changes, you'll never have to worry about the poles in Photoshop, or more importantly, in SL.

You still might end up with some "spider webbing" (I just made that term up, not sure what it's really called) from time to time, tracing fine streaks toward the poles, but those will be far less noticeable than a big black spots in the middle of your white surfaces (and easier to edit out in PS if you want to).

Another issue I see is you've got some visible shadow bleeding at the seams where objects meet, particularly on the center cushion. The bleeding appears to be more present on the right side of the cushion than on the left, suggesting that offestting the texture a little will probably help a bit. It's very common that textures need to be offest by .005 to align properly with the sculpt geometry. It's just a quirk of the implementation.

As for the dark lines framing the edges and corners of each object, I'd say you could stand to light your scene a bit better. Proper lighting can be very time consuming.

I'm not really an expert on the technique that author was going for though. I don't often work by compositing maps like that (although I probably should practice it more). I'd rather just build good shaders right in Maya to output a finished texture that doesn't require all that compositing and post processing. Maybe someone who does that stuff more than I do can chime in.

Much appreciated Chosen. I'll look into Turtle and work on moving the seams, thank you for the feedback.