(Solved) Jagged edges and overall low quality normal baking

Klawd

I'm really trying to get better with game assets, and hope you guys can help me improve...

here are the meshes:


Here's the uv mapping (where I think my issues lay).
I made the corners in two different ways to make tests, Left corner is straightened out, right corner has a more natural curve (but still made some uv relax passages)


Here are the results.
The lowpoly model I used here has a fully smoothed vertex map as you can see. Because if I harden those two edge loops, the (bad) baking results are almost non existent. Same goes with the cage, with or without it, I can't notice any differences.


How can I achieve better normals?
Thank you for reading this far.
Claudio

Bek

The major thing here is that your highpoly edges are so sharp, little to no information is being captured by the bake. Generally assets using a baked normal map tend to have exaggerated roundness/smoothness in the highpoly. The polycount wiki has a section on normal maps that cover a lot of this stuff:

wiki.polycount.com/wiki/Normal_map

As for the left/right thing: straight is generally better. Straighten as much as possible as long as the distortion is acceptable. This is to reduce aliasing. If it isn't clear why straighter is better, imagine a straight line in a texture. Now rotate it. The square pixels trying to represent a diagonal line have to alias or become jagged to represent that line. The lower the resolution, the more obvious this becomes.

Also modo has a feature to straighten stuff, try the "Rectangle" button in the UV editor layout.

Klawd

Hi Bek,

first of all, thank you, you don't know how much I appreciated you giving me some directions. I'm going to phagocytize that wiki now (I ignored it existed!).

Can I ask you a visual example of what you mean with the exaggerated roundness in the highpoly, with its lowpoly/normal bake for comparison?

And isn't there anything I can do to improve what the baking is able to extrapolate from the meshes I have at disposal? The upper edges, as you said, are in fact quite sharp, but they do have a roundness that the baking completely misses.

Bek

This age-old image shows an example with highpoly only:



A example showing the baked result would only be of limited value, because the only significant difference there comes from the texture resolution, which will vary per asset.

Klawd said:

And isn't there anything I can do to improve what the baking is able to extrapolate from the meshes I have at disposal?

You could increase the texture resolution. However, even if that's an option it doesn't make much sense unless this object is very, very large in scale. Like the example above shows, you need enough smoothness in screen-space for the edges to still appear smooth at a given distance. Hence the exaggeration.

If you haven't seen them already, this forum section (Tech Talk) has a few stickied threads that have a lot of good information in them about baking.

Another thing, looking at your lowpoly mesh: There is some unnecessary geometry — obvious examples being the edge loops right under the bevel. You (generally) only need geometry that affects the mesh silhouette in the lowpoly, though there are of course exceptions. But if those edges aren't doing anything, remove them.

This is also not something you need to be super concerned with right away, but I'll leave these links here anyway as they give a good understanding of the UV-lowpoly-normalmap relationship, which is pretty important for getting the best possible results, in terms of both efficiency and final result:

http://polycount.com/discussion/107196/youre-making-me-hard-making-sense-of-hard-edges-uvs-normal-maps-and-vertex-counts#latest
http://tech-artists.org/wiki/Beveling

Klawd

Hi Bek!
Again, thanks, that was very much appreciated, and it helped a lot!
I had not thought about trying 4k textures (original tests were in 2k), and it did actually improve the baking result. I also do get now what you meant with the exaggerated roundness and why it helps. 

My retopology skills are not the best, I have done very little of it yet, as you can see. (but I'm doing practice!) Those extra edges under the front are actually needed to keep together the geometry on the back side. Maybe I could try sliding them a bit in the front so as not to look cluttered.

Those links are gold, I'll make sure to read them carefully!
Thanks again.

Bek

There's probably no need for those edges to loop all around the model; you can terminate them once they're no longer contributing to the silhouette.

Klawd

Mmh ok, once I'll be more confident with my retopo skills I'll have a look at it again then.