Noob Question On Normal Map Baking / Skewing Problem (Revised)

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1

Hi…Can anyone tell me what I am doing wrong in the following example. My normal map baking is coming out skewed and after several days of head-scratching, I just can’t fathom out what the problem is.

The workflow is:-

1). I’ve created a default 222 cube. This will become the low poly object.
2). I’ve marked all the edges as seams and UV unwrapped it allowing a small margin between each face on the resulting map to deal with the future baked seam issue.
3). I’ve created a further default 222 cube, which will become the high poly object.
4). I’ve subdivided this a few times, bevelled the external edges, and then extruded four of the faces to provide some detail to bake down to the LP object. The HP cube now looks as follows.

[ATTACH=CONFIG]476544[/ATTACH]

5). As I’m using cycles, I’ve then created a new material, and new image in which to store the resulting bake.

6). I then go ahead and bake, the results being as expected. Exporting both the LP object as an FX and the resulting normal map into Marmoset produces the expected result:

[ATTACH=CONFIG]476545[/ATTACH]

7). I now need to fix the issue with the seams, so I create a further 222 cube which will be my cage. I scale this to be slightly larger than the HP and LP objects. I specify the cage object and bake again.

8). Whilst the seams are now fixed, I have another problem in that the “high poly” details are skewed. After reading the really useful polycount thread “http://polycount.com/discussion/147227/skew-you-buddy-making-sense-of-skewed-normal-map-details” the problem seems pretty obvious. I just need to add some further control loops to the low poly object to control the normals.

9). I go ahead and do this, re-create the cage, and re-bake. Unfortunately this has no effect on the bake and the high poly detail remains skewed.

[ATTACH=CONFIG]476546[/ATTACH]

And this is the problem, what on earth do I do to fix the skewing issue ?

I don’t understand why the additional control loops aren’t resolving the skew as per the article ?

Any help would be very welcome as I am at a loss as to what I am doing wrong. :o(

Thanks,

Nick

Attachments

WhyAmIGettingTheSkew.blend (588 KB)

2

Without looking at your .blend, it’s hard to say what your barrier is. I don’t usually bake cubes, but in attempting just now, option 5 (inset method) within your link works perfectly for me. If you upload the blend to pasteall.org, I’m sure we can steer you in the right direction rather quickly.

3

Hi Derek, many thanks for your reply.

I have uploaded the file “WhyAmIGettingTheSkew.blend” to pasteall.org. I had also tried to attach it to the post, and then for what ever reason the post content seems to have vanished. I can re-post if required.

Thank you in anticipation of any help you can offer. I did try the inset method ( adding and inset face to both the low poly object and the cage ) before replying but it made no difference. Clearly I am doing something silly somewhere.

4

Have a look at this .blend. All I did was inset, duplicate/fatten the LP for a cage and bake. No skewing. See if you can replicate it.

Also, just something to watch out for, occasionally Blender won’t update the internal image after the bake. But if you save that image and refresh, or relink it in the UV editor, it will update. So it’s possible that you’ve baked it correctly and not realized it.

5

Well after another 45-minutes of head-scratching, I’ve found the problem. You must manipulate the cage using the displace modifier and not just scale it as I had been doing. Scaling does not work.

Thanks for your input on this one, at least I can stop banging my head against the wall now!

6

Sorry, Nick. I didn’t realize that was the issue you were having. The displacement modifier works, but using shrink/fatten (alt S) instead of scaling is more flexible and is more direct.

7

Not a problem Derek, I wasn’t actually aware of alt+s so thats another thing learned. Thanks again… :wink: