Hi
If I have a bumpmap to reflect tooling operations or a burnished finish on a part (not a lathe), what would be a good approach to create a map that controls anisotropic rotation?
Example of such a bumpmap here:
http://content.luxology.com/asset/exref/707eb86bc61959b399759bb3aeb5e41f.png
I don’t expect it to be possible to have an automatic way, so how would you go about to create a matching direction ma by hand?
There is a short explanation for creating those maps in the manual for modo 601. Not sure, though, if Cycles uses the same kind of maps…?
Those as same as Blender, except we use black->white to depict 0°-360°. But those are straightforward to produce. What if I had the letters “ROFL” where the bumps would appear naturally as per tooling (milling machine). From those bumps, flowing how the milling machine would produce them, how would I create an anisotropic rotation map?
My head is spinning towards brush stroking it out manually, where brightness of stroke is dependent on my direction of stroke in order to draw perpendicular to the bumps. If there is another, maybe better way, I’d like to know. If not, I’d still like to know how I could stroke it out in that fashion.
That one is also extremely simple though, as it’s only two angles which gives only two colors. For the original bumpmap there, imagine if you noised up the input vectors in such a way that even the banding were curved (not a single shade at a straight angle). Now what, wrt creating the rotation map?
On this image you can see the bumps left by the tooling process. Creating bumps is easy, you just draw what you see. But how would go about to create a matching rotation map from this?
It was just a simple example. To get a more complex pattern, just use a more complex map - e.g.
If you imagine the rotation angle depends on the grey scale - if you want a specific angle on a specific part of your model - you match the shade of grey to the angle you want. For something like your picture - where the angle is varying constantly - you’ll need a smooth transition from black to white or from one shade of grey to another.
Are there any tools available for this (if at all possible)? If using a paint program and doing it manually, is there a way to color the stroke by the direction I’m stroking?
Anyone looking for this in the future here’s a machine turn pattern I made. It seems to work better than plugging a standard tangent map into the rotation.
Machine_Turn_Textures.zip (1.8 MB)Well, as long as this was bumped anyways…
I haven’t done it. But I would think you could make a rotation map using a smudge tool and some image processing. Take any reasonably complicated picture-- white noise might work-- and smudge your directions. Then, for each pixel of your smudged image, compare to 8 adjacent pixels. (Details on that in a second though.) Pick the adjacent pixel with the closest match, maybe an HCL Euclidean distance. Compare the two neighbors-of-both and pick the closest match. Look at difference between closest and next-closest to calculate a rotation with a resolution higher than 8.
There isn’t really a difference between 360 and 180 rotation for this purpose (does Blender actually map 0-1 to 0-360? I dunno) and your smudge will actually give you two vectors, so you won’t actually be looking at all 8 neighbors, but only at 4 on a preferred vector. For border pixels where this isn’t possible, you’ll be assuming symmetry across the pixel. Or assuming tiling, I guess.
For most uses, you’d probably have to process again, to make these rotations relative to the UV tangent.
Seams would probably be difficult. (We need somebody to make us a utility to create a seam-aware UV lookup for margins.)
But polycount has some information on painting flow maps that I haven’t looked at in depth. That’s basically what you want to use, although you’d be doing some processing, converting vectors to angles. http://wiki.polycount.com/wiki/Flow_map
I just spotted a flow map painting utility on the Polycount website. I haven’t installed it yet, but it might be useful (assuming it’s standalone). http://teckartist.com/?page_id=107
