VOP's

Nick23 · VOP's

Hi All

I would really like to learn more about all areas of VOP's, I can see the potential and power it offers. Is there any tutorials out there? I can't find much info about it.

Are you guys at CMIVFX planning to create a tutorial DVD on VOP's. I've just purchased the L-Systems DVD and am learning heaps, a VOP's
DVD would be awesome.

Also does anybody know how to create a simple ramp in VOP's like the one in COP's? Please Help

Thanks
NIck Sullivan, Sydney

admin · absolutely

VOP's of course we are. We wont quit until everyone is a houdini expert. Wink

stand by for more by david.

Nick23 · VOP DVD

Unreal! I can't wait, any idea when it might become avaliable?
The L-Systems DVD is awesome, I didn't realise the power that the L-System SOP offered.
My thoughts exactly everyone should learn Houdini, It's not that scary!

Thanks again
Nick Sullivan, Sydney

david gary

About the L-systems DVD. Thanks very much!
And remember this is only the first of 4 DVDs devoted to L-systems.
In the following: you will learn how to animate a tree ( with DOPs, reacting to wind of course, but also using branches as tentacles), how to create realistic fully contollable crack patterns , how to grow and paint plants on any surface, with much more options than Maya PaintFX ,how to create more elaborate tree geomtry and corals, how to shade and render them how to create a city pattern growing ( with some extended fully-scriptable l-systems) and more (Lsystems in Lsytems, snowflakes, recursive modeling at the very end...).

About VOPS. ( after l-systems.. sorry).

Sure we will release DVD(s) about VOPs! DVDs released for now assume that the user has already a basic expertise with VEX. But there is a HUGE AMOUNT of things to say and to do with VOPs.
Vops can achieve some very different tasks.

In shading contexts it is nothing less than a shading language which is as powerful and often more than renderman RSL ( more options, such as all the raytracing features that were here before renderman, the Point Clouds, the i3d prior to raymarching...).
When we teach VOPs in rendering, we will actually teach rendering from A to Z ( Z being what a real TD must know!)

In SOP context, it is nothing less than a tool to create any kind of deformation that you want, it's an entire field.
One of the limitations though is that it works on points, and you may want to make it work on primitives. It is possible with one or two simple tricks as long the operation you want to do with primitives is possible.. ( primitives are dependent upon points).

In particle context, they replace all the tedious expressions and open Houdini to the immense field of behavioural animation.

Of course CHOP context is an "abstract" context because channels can be anything you want.

COP context is similar to surface shading context in shading context: it allows to create any procedurally generated texture that you want, but since it can work with multiple inputs, it can create all the scripted compositing filters that you want and that you usually use in Shake/Nuke/Fusion, any transition that you want by animating the parameters.

Yep, Vops are incredibly powerful. they are a visual programming environment for VEX: which means if you know how to read a VOP network as a replacement for code, you don't make syntax errors ( no debugging!) How great is that?!!

All this topics will be covered in the further DVDs with a special mention for shader writing and rendering

About a Vex Ramp you can use the Ramps VOP. It depends on how is you ramp ( vertical/radial)...
Cheers.
David

FEEL FREE TO LIST ANY PARTICULAR TOPIC YOU WOULD WANT TO BE COVERED, SPECIAL QUESTIONS TO HELP US MAKE DVDs EVEN CLOSER TO YOUR NEEDS. THIS INFO IS REALLY PRECIOUS TO US!

Nick23

What a reply!! I can't wait for the other L-System DVD's, They sound great. Also the much anticipated VOPS DVD's, I'll have a think about the topics I'd like covered.

Is it going to be possible to recieve a cheaper price if buying all of the DVD's on a particular topic.

Cheers
Nick Sullivan, Sydney

steve

david gary

Hi Steve! Very busy indeed..

1. Point clouds are just... sets of points with some attributes associated stored in a good way for lookup/access. They're used to fake GI ( to instance multiple lights) but also to fake SSS ( the trick is a little bit more complicated)...

2. Well, yes. A i3d is a three dimensional texture which is not procedural...
So this is something very very heavy ( to have equivalent quality as 2d 2000*2000 texture you will need to have 2000 ! textures for the third dimension), both at CREATION ( the file is big) and when it's used in shaders: render times are very long.
It actually stores a unique value which is the density and which is "integrated" along a ray .
We will teach it because if we teach rendering, we will teach everything. But clearly having a good understanding on how raymarching works ( which is not that difficult when you've already put your hands into shaders) is much much better and much much quicker since you will then compute the density procedurally which doesn't use any texture ( much lighter and faster ), and which is much more precise.

3- I have no special info about this. i3d is inherently something very big to handle: SESI can make them better with faster texture access, but i think that's the maximum they can do.

So, you know some french, Smile

then i will answer:
Je considère que nous n'avons pas véritablement perdu la coupe du monde , je trouve que nous étions vraiment meilleurs et plus solides. Et sans l'exclusion de Zidane, nous aurions bien évidemment gagné. About next world cups... that's another story! Smile

steve

That's just what I needed to hear. Thanks alot David, but to continue this just a little bit more (just a little bit, I promise haha):

If I3D is heavy and long on the pc, why is it used? Why not just bother adapt some form of raymarcher for Houdini (and is this possible by the way?)?

Ne commence surtout pas a propos de Zidane Exclamation

Moose

Hi David

Just wanted to chime in as someone else who's very keen to see more material for vops. No preferences per se... just all of it really Very Happy

. After vops, my next weakest area is in chops (if you're looking for a direction to go in...).

Hopefully if sesi can nail the new workflow changes announced for H9, more non-houdini types may give it a shot. Having lots of video training for them to lap-up might prove to be the deciding factor.

Oh and great work on the l-sys dvd - cant wait for the next one!

Smile

david gary

Hi, Steve ( the answer to Moose follows in page 2)

About i3d.
Several explanations about how it's still used ( these explanations are mine, i don't say they're the exact ones)
First thing is that i3d can also be used in modeling with the IsoSurface SOP ( which creates implicit surfaces). It's much more interesting in this context because it doesn't require the same amount of detail. I guess SESI wanted to have a unified 3dimensional-array-of-data file format.
Why is it also kept in rendering? Maybe it's beacuse people are afraid of writing a "ray marching" piece of code.
About raymarching. I should say ray marching ( in two words). I didn't explain what it is. It just consists in iterating a loop along a ray ( this has not to be implemented in Houdini, it's just the name of a technique and it was already used in Renderman when it didn't support raytracing). What is implemented in Houdini is integrate3d which performs ray marching through a texture. But you can implement it creating a virtual
ray ( just a point and a direction).

Ton français est bon.. But, to be honest, i'm not a big football fan, so we won't go long on this topic Smile

david gary

Hi Moose,

Great to have feedback and to know what people want. Thanks!
About CHOP, it's funny, before the topic was raised in this forum, i was rather inclined to think about making a DVD about CHOPs. Actually, I 've already made a list of CHOP topics. A conversation in odforce made me realize that people don't use them enough because there isn't any tutorial about them.

I love CHOPs ( i will use some of their unique features in the second l-system DVD).
But there's a lot you can do with them.

-interactive animation (using keyboard, mouse, midi input, like how they used them with the Wii-mote joypads, and the Touch software of course:
http://derivativeinc.com/home/home.asp
-audio-driven and audio-related animation
-non-linear animation of characters and in general, motion retargeting ( which only appears now in major apps while the ability to do that exists since the early versions of Houdini).
And since channels are just data in general (CHOPs are kind of abstract operators) there is a LOT of things like Geometry deformation with Geometry CHOP, iterative animation ( just like how particles do : the state at frame n is computed from the state at frame n-1) with the Feedback CHOP.

Actually CHOP may come before VOPs...

About the evolution of the workflow. I personally wouldn't like the workflow to change, maybe some updates here and there ( i don't want Houdini to loose its proceduralism to be like others) It has been said the interface and the icons will change to something more fancy, more "candy-looking" which i don't specially like ( it's disturbing).
I will have to learn Python for the new Hscript-expression unified language ( based on Python). I really want to know more about H9..

Moose

steve

Hmm I don't know how to multiple quote people so I apologize:

1- Thanks David, you pretty much answered all my intrigues. My French is somewhat good because I live in Montreal and I attended 12 years of French school. Ouch. Smile

.

2- Moose, stop saying how good the l-system DVDs are, I’m waiting on the shipment of mine!

3- Chops, Vops, Cops, Sops… What ever you plan on teaching, no matter the order I’m going to learn a handful, and I’m pretty sure most Houdini apprentices feel the same way.

4- I’ve been trying to pick up python for usage in Realflow, hopefully once Houdini v9 comes out I will have learned the basics of the language. For some reason, I feel like David is going to read 1 light book on it, maybe check out one or two tutorials, and in the matter of like 8 days he will know python inside out… Anyone else thinking the same thing haha?

5- As for the change in the interface…They better not change it, I’m having a hard enough time picking it up as it is Smile

. Making some friendlier buttons wouldn’t be a disaster though; I think sesi is trying to open up the app to a wider market.

6- I don’t like football either David, but when it comes to this sport, France is definitely Italy’s biggest rival. Smile

admin · the curse

Steve,

It is the cmi curse that changes the UI's of all the apps we start to teach.

Everytime we pick up a product and start training for it, it immediately gets revamped after are first couple of titles. Its almost humorous.

Anyway, despite that info....

I wanted to cover some specific workflow techniques in the to the DVD's more than just specific operators. LSYSTEMS was actually an idea i had many moons ago, but was going to be called into a different category of training. David convinced me that most people dont have the basics down in this area, that is why we went with the node group and essentials.

BUT, id rather show CHOPs in its natural element more than, general manual of operations. At least you can learn where the stuff is AND learn a trick or two the technique based way.

Same goes for VOPs of course. we will have some internal discussions of the route we will take after the closing operational Lsystems DVD's.

Most likely, you will see some more fx breakdowns of real world situations. MUCH LIKE THE CITIES DVD.

-c

steve

That sounds awsome. So they are going to be project based once again? Good, I'm not a fan of a tutorial that's bassicly a video format of the program's manual if you get my drift.

admin · drift gotten

Steve,

Dont you worry... I HATE BUTTON CLICKING TUTORIALS!

I leave that to the blokes who cant come up with real life lessons.

Many people start off with those tuts. But they still have no clue why they are in the app to begin with.

Wink

-c

xzhang

Hi, David:
Will you consider the subject of a procedure crowd system,
that will be very very interesting.

for HOUDINI 9, some condidates for you:
fluid,
fur/hair/grass
volumetric shading/rendering
with all the previous interesting topics, you can make a nice tutorial collections
for us i believe.
thanks for all the great works.
:O)
xiao

admin · crowdz

xzhang,

Yes this is a concern for cmi. We will be unraveling the variety of crowd sim situations and tacking it from a few angles.

This is on my list for this up coming half of year. The main issue is digital agents. Lots to figure out to make it as hot as massive is.

-chris

xzhang

a suggestion for VOP DVD, maybe you guys can address some anti aliasing
techniques usable for production.

radiohead

Hi anyword on VEX DVD series?
I am about to buy all 3 houdini dvd but if there are any more dvds coming out, i will wait ..

david gary

well well well.
it's hard to keep things entirely secret
Well what i can say is that the new series about VEX is coming soon ( around september)
It's about VEX/VOP in general( inter-contexts) and in SOP context ( which means how to create custom surface operators), extremely detailed.
You will learn everything about this powerful language.You will learn how to create/script complex deformers ( like lattice/metaball/wrap deformers), fractal terrain modeling ( all the main operations that you can do in Terragen: glaciate/canyonize-reshape, snow-grass procedural "textures", geological events but also oceans, )how to create realistic cracking effects.
Plus a lot of other things i don't mention here cos i want to keep the surprise
All the DVDs should be released at the same time.

I want to insist on the fact that it will be as much a reference on VEX language, syntax, constructs and interface customization as a comprehensive mathematical cookbook for procedural modeling.

Definitely something to regularly come back to, i tried to make it " easy like video but rich like a book" ( a subtle mix of ingredients that took some important time to properly organize)

And Remember this is just VEX for modeling !
We do not cover yet all the particle/behavioural animation with VEX POP, procedural animation with VEX CHOPS, custom compositing filters with VEX COPS or all the VEX shaders ( surface/displacement/raytracing/fog/photons ....). But this is on our list of course. VEX is an IMMENSE field.

-d

Alanw

David, I think the 1st VEX DVD is amazing so far. I cannot wait to learn more about VEX in regards to POPS and Shading in the future.

One thing that is difficult for me is the mathematics involved with the SOP deformer. Do you have any recommendations to go along with this DVD to help understand the math a little better? I remember some of this from college, but it's been too long.

Thanks

david gary

Hi about maths reference.
It's hard to tell since i learned math in college and with french books.
But
1) most of good books about computer graphics have a good math appendix
like these two wonderful ones:
http://www.amazon.com/Advanced-Re...g-Pictures-Kaufmann/dp/1558606181
http://www.amazon.fr/Computer-Ani...thms-Richard-Parent/dp/1558605797 ( although a little old maybe but still incredibly useful)
These two books are AMAZING, well wriiten and so useful!

So it's good when you're also doing something precise with this maths.
2) well, nothing better than browsing internet or googling "matrices" or "trignometry", or the wikipedia and the forums.

-d

Alanw

Thanks for the advice. This is exactly what I'm looking for.

VOP's

absolutely

VOP DVD

the curse

drift gotten

crowdz