max2010 bake artifacts

marks

Baking a normalmap from highpoly mesh onto lowpoly using scanline render-to-texture (ray distance, no cage). Getting some weird banding type artifacts on a lot of edges, like the normals seem to be being rendered correctly every alternate pixel along the edge on some UV islands, some different like below. Any ideas?

Eric Chadwick

That's the edge padding, shouldn't affect your shaded model, in fact you need the padding to avoid seams.

DarthNater

If it IS effecting your model though, turn the padding down a bit. It looks like in that second images your padding is jumping into an area of your UV's (the pink area on the bottom left). You could either move that piece over a bit, or turn the padding down a little.

Eric Chadwick

Nope, padding never jumps into the UVs. The cyan to the right is more padding, not UV interior.

DarthNater

EricChadwick wrote: »

Nope, padding never jumps into the UVs. The cyan to the right is more padding, not UV interior.

Really? Well now I look stupid :P Good to know though, I thought I had that happen before but I guess not

Eric Chadwick

No biggie. The padding can look weird and banded like this, but it doesn't cause any harm.

The whole purpose of the bleed is to prevent incorrect edge colors from blending into your texture when the texture is filtered down by the renderer, so the banding usually "disappears" when the texture down-samples (mips) are fetched by the renderer.

marks

Interestingly, if I bake using a simple cage (reset cage in projection modifier, push by like 2.0) I get no banding artifacts on the padding, just smooth colour gradients. However, thanks for the informative (and speedy) response, very insightful.

DarthNater

Eric is full of knowledge

I usually use the cage on everything that has a lot of geometry and not use it when I bake simple things like 'cover blocks' or pipes...

EarthQuake

if you've got smoothing groups set up(hard edges) baking with an offset instead of a cage will result in missed detail at the edges, as the hard edges are "broken" during the back process and expand independently. Using cage means that your hard edges will all be welded and seamless instead. This would result in some different results when comparing the two methods.

The cage method is very good for getting seamless bakes, and its pretty essential to capturing that "high poly" look on your low. However it tends to "skew" details a bit more as the projection angle is averaged. So sometimes it is good to do two bakes, one with cage, one with offset, and then combine the results in photoshop so that you get the best of both worlds(seamless edges from cage, straight, non-smooth details from smoothing groups+offset). You can also simply add in some more geometry to help straighten out skewed details, and if you have the budget to do so, this is by far the best solution.

Now if your model doesn't have any smoothing groups/hard edges set up, there really isn't much difference between cage and offset.

Also, more padding is never bad. Use 32 pixels of padding! This will never ever ever be a bad thing. When you have a 2048x2048 texture mipped down to 256x256 you can bet your 4 pixels of padding are not going to be enough.

Eric Chadwick

Good stuff.

dtschultz

What's baking with an offset? I've only used the cage. Thanks!

EarthQuake

In the RTT bake options there is a tick for "use offset" this over-rides your cage and simply uses a distance value to offset instead, i think the default is 10.

dtschultz

Ah, thanks! I'll have to try using the two methods and averaging out the maps, like you suggested..

DarthNater

EarthQuake wrote: »

In the RTT bake options there is a tick for "use offset" this over-rides your cage and simply uses a distance value to offset instead, i think the default is 10.

You are correct sir, 10 is default. I usually have to start at about 20 though, seems to be the magic number