Question regarding normalmap using zbrush and maya

RE3456

Hi guys I have couple questions regarding normal mapping, please help me out. I build this low poly model to test out normal mapping, first I build the model in maya, lay out the UVs and imported it into zbrush. I added some details using zbrush and I used zmapper to generate a normal map for me. I then bring the normal map into maya, applied it to the model and this is the result I have, as you can see there is a really noticeable seam along border edge of the UVs, also the normal on the right arm of the character seems to be inverted, it was suppose to look the same as the left arm.



Another question is about rendering in maya, I'm not really familiar with metal ray render but I heard so many good things about JS_Normalmap mental ray shader for rendering normal map so I decided to DL it and give it a try and here is a picture of the result I have. Seems like I have some really weird shading going on with the render, did I missed to adjust some options inside metal ray? or is there a better way to render normal map objects in maya?


Any help would be greatly appreciated.



Thank you

MoP

It looks like it's currently rendering the normal-map with the Y-axis inverted, so try inverting the Green channel of your normal-map in Photoshop (so white becomes black and vice-versa).

That should fix the weird shading, but with regards to seams, I'm not sure - that may be something to do with the way ZBrush outputs normal-maps, but I haven't got enough experience in that area to say for sure.

rooster

I found a couple seems from my zbrush normals that didnt show in zmapper actually, there was some option that made them appear though.. cant remember off the top of my head. There was also a slight inverting glitch in one leg, but I just copied the normals over from the other. I'd love to hear an explanation. I haven't RTFM yet though

Jay Evans

ya, I ran into this seam problem recently myself. When doing normal maps in zbrush the old way it never happens. Since i started using Zmapper I ran into it. It must be just a Zmapper option somewhere that I haven't found yet. Of course i could read the 100+ page zmapper doc.. but where is the fun in that:p I know zmapper has various presets you can load for differnt types of normal map outputs. You may want to look into that.

RE3456

thanks for the help guys, what really annoys me is that when in the zmapper preview the seam is not as noticeable as when I brought map into maya so if I want to test out the options in zmapper I have to actually generate the map first and then bring it into maya to see the result. Anyway I will keep seek answer for this one, if I figure anything out I will post here asap

rooster

one of those expert options in zmapper will show you the seams, er its towards the right area of the options box, in the second last extra options thingy. I think

RE3456

thanks rooster, though I couldn't quite figure out which option you are talking about, still trying to figure out how to get rid of the seams, already play around with some of the options but so far no luck

rooster

I'll look it up when I get home, sorry to be so vague. Still, it doesn't really help with fixing em

RE3456

I still couldn't figure this one, really really need help.

PaK

One of our art diorectors noticed this. download the crytek polybump viewer and see if your problems persist *but first* you try inverting your green channel as per the suggestion above; and see if that fixes your problem.

Our AD discovered that maya doesnt handle normal map seams very well and draws problems where other renderers draw none.

I'm no maya expert so...I cant be sure. I hope that helps.

-R

Jeff Parrott

It's really only the second version that Maya's been able to view normal maps properly. Hopefully they'll work that out when it becomes Maxa at SIGGRAPH.

rooster

sorry for the late input, the button I mentioned that displays the seam problems is 'derive normal from tangent x binormal' I haven't read up on this yet, but it might give you a starting point to research