Hard Surface Normal maps

monkeyboy_garth

Hey fellas, I'm making this dumpster for texturing practise but I'm stuck with getting the normals to bake properly. I'm getting these gradients across what should be flat surfaces on my dumpster. It's screwing up the lighting in the viewport.

Weird thing is that when I render it in max, it appears okay. Anyone know what I could be doing wrong?

bugo

it seems that your nmap have a inverted green channel, weird that your 3ds max render rendered it ok, that´s kinda impossible, so I believe that maybe your smoothing groups are all in 1, you should try to add some smoothgroups in a way your nmaps can garantee a good surfacing.

Eric Chadwick

Nope, you just need a better viewport shader. The default ones are all bad. If it looks correct when rendered, then it will be fine if you use the correct viewport shader. More info about why this happens...
http://wiki.polycount.net/Normal_Map#TangentBasis

monkeyboy_garth

Hey EricChadwick and Bugo - thanks for your help. I've tried both solutions and still nothing is really helping.

Not sure if this should matter, but when I baked the normal maps, I separated out the different sections. ie the rims across the top and bottom were detached and rendered separate from the main body of the bin, then when they were welded back together, I just gave the rims a different smoothing group.

As you can see, the rim across the top of the bin and the side catcher bit is still getting weird lighting probs. With the BRDF shader, I've shown the light colours to try help with sorting out what's going on. I have to settle with default light with the BRDF shader. For some reason, I specify my three lights but they aren't making any difference.

Chai

Ye, that's smoothing errors which you get when doing hardsurface normalmaps.
I wrote an article explaining them and possible solutions, hope it helps
http://www.svartberg.com/tutorials/article_normalmaps/normalmaps.html

monkeyboy_garth

Hey, Chai. Thanks - I'll give that a try!

Sage

The way I found to avoid this is to add one smoothing group to the low. If it looks like it has shading issues add edges as if you were going to subdivide. Do this until the shading looks good. The Idea is to get an even distribution of edges across your model, like when you make a primitive and give it extra segments. You don't have to add a lot though.

Alex

monkeyboy_garth

Thanks fellas. I chamfered some of the hard edges surrounding trouble areas and baked again and voila - the shading problems are gone. Yay! Time to move on.