Hey guys,
I'm a bit frustrated that I see so many tuts where normals get pushed around and modified with various expressions and I just don't understand what is really going on there. I could follow the steps but I don't really understand what they're doing.
Well, I generally know what a normal is but I don't know much about the math behind it and in Houdini it seems to play somewhat of a big role.
So I wanna know if you can recommend some tuts that cover specifically the math behind normals? I think that understanding this topic fully goes a long way in Houdini.
It's years ago where I saw this fxphd course about math and I think they covered vectors and normals in that but my brain at that time just wasn't ready for it yet.

Korny Klown2
Hey guys,
I'm a bit frustrated that I see so many tuts where normals get pushed around and modified with various expressions and I just don't understand what is really going on there. I could follow the steps but I don't really understand what they're doing.
.

Do you have an example ?

Unfortunatelly not really. Not one example in particular but basically every tut where the instructor uses a point SOP, types some expression in the normals section and I don't know what this expression does, what the math behind it is, and so on. When I'm watching these tuts I either cut the tut at this point or just follow the steps, unable to reproduce what I just did on my own, because I don't really understand it. There are of course also other nodes, besides the poinbt SOP, that manipulate normals, not to mention all kinds of VOPs. At least here one should have a decent understanding of vectors and normals.
If you want I can post some of these tuts, if you think it helps you to help me but still my question is rather general and not related to one specific task or tut.


Let's start with these tuts, just as placeholders:

http://www.cgmeetup.net/home/dynamics-houdini-tutorial/ [cgmeetup.net]
at about 27:50 he introduces a point SOP, uses some expressions and I'm out.

https://www.sidefx.com/images/stories/tutorials/orient_sweep/sweep_orient_to_curve.mov [sidefx.com]
here, somewhere right before the middle he introduces a point SOP and once again I have no clou what he's doing there.

Hi,
Often or not the user never explains, but there's nothing to stop you doing some digging.
Garman Herigstad is a great teacher and I know him personally watch his houdini math videos https://www.youtube.com/user/vizylists/playlists [youtube.com]

Just so you know I also even after years of using Houdini still sometimes really have to do some digging to grasp a new concept , it helps to ask lot of questions ! ie with the new vex wrangle

Keep scene files and make notes !

Though not specific to Houdini, here are some additional resources about surfaces and their properties:



https://en.wikipedia.org/wiki/Surface_normal [en.wikipedia.org]
http://blog.db-in.com/calculating-normals-and-tangent-space/ [blog.db-in.com]
http://fullonsoftware.co.uk/snippets/content/Math_-_Calculating_Face_Normals.pdf [fullonsoftware.co.uk]
http://tech-artists.org/wiki/Normal_map [tech-artists.org]
http://mathworld.wolfram.com/NormalVector.html [mathworld.wolfram.com]
http://na.industrial.panasonic.com/blog/measurement-sensors-specular-vs-diffuse [na.industrial.panasonic.com]

circusmonkey
Hi,
Often or not the user never explains, but there's nothing to stop you doing some digging.
Garman Herigstad is a great teacher and I know him personally watch his houdini math videos https://www.youtube.com/user/vizylists/playlists [youtube.com]

Oh man, this guy has a lot of stuff going on, on his channel, why havn't I found anything of him yet. So many times I was searching on YouTube for Houdini tuts…
…so now I have a lot to watch….

Chronon
https://en.wikipedia.org/wiki/Surface_normal [en.wikipedia.org]
http://blog.db-in.com/calculating-normals-and-tangent-space/ [blog.db-in.com]
http://fullonsoftware.co.uk/snippets/content/Math_-_Calculating_Face_Normals.pdf [fullonsoftware.co.uk]
http://tech-artists.org/wiki/Normal_map [tech-artists.org]
http://mathworld.wolfram.com/NormalVector.html [mathworld.wolfram.com]
http://na.industrial.panasonic.com/blog/measurement-sensors-specular-vs-diffuse [na.industrial.panasonic.com]

… and a lot to read.
I already have a chaotic pile of papers flying around on my desk, trying to solve these equations and getting a decent grasp on this topic.

Thanks for the resources