Head Phone Normal mapping number 2

It seems that the deeper I delve into normal mapping, the more theory there is. There's more to just making a high res and low res and hitting bake.
I started by just altering my low resolution's bake cage in order to improve my bake. For personal work this is okay, but that cage has to be remade for every single bake. I think a professional setting that this is very destructive and very time consuming; if someone down the line has to take your asset and make Normal map changes, they will never be able to create the same circumstances to achieve the same bake. Even more so, I was painting out artifacts inside Photoshop to clean up my Normal maps. I don't think this too is a good idea, for professional settings. Instead I am going to focus on trying to learn how to create the best Low res models for normal map baking in order to get as close to the best result as I can. This way I can avoid altering baking cages and tweaking so much bad baking in Photoshop all together.

This is probably going over a lot of peoples heads. Trust me, it's confusing me. Normal map baking has a lot of theory, and it's very underestimated in the industry today, meaning a lot of people just hit bake and clean up in Photoshop.. Not a lot of people talk about it and I'd love to become very well versed in the technical aspects of it.

Things I've learnt :

There are two ways of baking a Normal map.
As someone on the Polycount website 'Earthquake' (one of the industry forerunners in Normal map baking theory) writes:
  • “Averaged projection mesh”
This method will ignore your lowpoly mesh normals, meaning if you have hard edges/smoothing or any sort of custom edited normals on your lowpoly the “bake” mesh will average everything. The biggest advantage here is that you can use hard edges without any seams or negative artifacts.

  • “Explicit mesh normals”
This method uses the lowpoly mesh normals directly for your projection direction. What this means is if you have hard edges or smoothing group splits on your lowpoly your “bake mesh” will also have those splits, and you will get gaps in your bake in those areas.

If you’re using this method, but making sure to avoid any hard edges/smoothing group splits, all you’re really doing is using an “Averaged projection mesh” but without the inherent benefits of using an “Averaged projection mesh”(like the ability to use hard edges). Suggesting others should do so is akin to saying “never use triangles”, or “always use quads”, it’s simply bad advice that doesn’t tell the whole story, and confuses novice users more than it helps.


More jibberish no doubt. But as I delve further, I begin to understand a lot of what he is saying.
Something I've learnt so far :

Making edge normals 'hard' doubles the vertex count on that vert. This impacts performance. UV seams too by this logic double the vertex counts on the verts that the seams follow. This doesn't stack, you can harden the edge along a UV seam and it will still only double the vert count. Thus giving you the hard edge for free and zero extra performance hit. There's no reason not to harden edges on UV Borders (you don't have too, but it's good in theory)

So here's an image of another bake I've tried. There are still wavy line issues, I need to figure this out next. But the bake is rather nice I think. I want to try and eradicate these wavy lines by altering the low poly, not the cage and certainly not painting them out in Photoshop. I believe that this comes down to the low res not matching up with the high enough. Cylinders are tough to bake because of this.
It's simply a 'not enough geometry' issue.

Enough of that. Image!

Normal mapping is definitely very fascinating. It's something I'd like to become a lot more well versed in. I think someone who has the knowledge to create Low polygons that work in harmony with the high resolution models to create clean bakes as opposed to messy ones that have to be cleaned up manually (causing all sorts of problems in a professional pipeline) is definitely a lot more employable.  

edit: ( I just noticed a glitch in my UV at the top there, this explains some of the baking errors I've been seeing. Silly not to have noticed that one. :D) 

Also, below you can see the headphones on a silhouette. This is probably the closest you'd see them on this model. They look nice :)

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I am a video game artist at Dovetail games, working on Train Simulator 2014, 2015 and an unannounced title. I also graduated from the CG Arts course at UCA in 2010 with a First Class. www.jonstewart.co.uk