Learning Houdini Journal 05: Polygonal Modeling

Nov 29, 2015 at 12:06 am by -gToon

This is the fifth entry of what will be a year-long journal on learning the 3D application Houdini, created by Side Effects Software. Houdini is a sophisticated application that is widely used in the production of visual effects for Hollywood films such as Big Hero 6, Mad Max: Fury Road and many others.

In my previous Learning Houdini Journal 04, I talked about being more committed to the learning process. It takes a slow, every day commitment to develop a habit. Self-directed learning requires patience and consistent application.

Back on Track with Learning Geometry in Houdini 15

Well, it's working for me. Daily application, even if it's only 15 minutes develops a habit which in turn kindles enthusiasm and interest. I've been working the Pluralsight (previously known as Digital Tutors) Introduction to Houdini 15 every day for the last week and am enjoying the process very much.

The course is centered around learning the basics of Houdini 15 by completing a simple scene: a race car crashing through a window out of a skyscraper and arching down to the street. This approach is smart because you end up learning several different aspects of Houdini by the end of the course, which is very well taught by instructor John Moncrief.

Course Image
Final result of Houdini 15 course

One question I asked myself back in a previous journal was, "Can you use Houdini tools directly on an imported model (.obj format)?". Now, I feel stupid for having asked the question because it's so obvious that you can. Houdini has a full range of polygonal modeling tools many of which are as good as or better than it's competitors. Add to that the fact that you can choose to either manipulate the geometry via the network node or tool from the tool shelf and you have a very powerful modeling set at your disposal.

The polyextrude node is really simple to use once you get the hang of it. Select the geometry, hit the Q key and you have another segment of your object to extrude. In the tutorial, I'm creating a hub and a wheel for the car and after a few stutter steps I've got it half-way modeled.

The polyextrude node at work

I didn't model the car, as it was included in the course materials. I like how the instructor simplifies the process, but still gives you the benefit of basic modeling skills in Houdini 15. I'm also impressed with how smartly all of the tools are laid out in Houdini 15. Once you learn the keyboard shortcuts and how to read the interface, the process becomes transparent.

The Uncooked Node and the Unwireable Node

Strangely, I had two frustrating problems as I was learning the modeling process. The first came about when I added a new node and found that I couldn't wire it up (attach it to another node) because it had red lines in it. But if I closed the program and restarted the node was fine (no red lines). After research, I discovered that the red lines where a sign that the node is "uncooked" and not usable. Sidefx.com forums to the rescue. A smart, veteran user pointed out to me after I posted about it, that the node is uncooked UNTIL you wire it up.

Ooh, that nasty, uncooked node!

This problem dove-tailed into another rookie mistake I made: the fact that I couldn't seem to get the wire out of one node to attach it to another. I discovered that I was holding down the left mouse button while trying to attach one node to another. In practice, you click the node-end once, then release the mouse. Now the wire appears and you can attach one node to another. Such a simple misunderstanding on my part cost me about an hour of frustration. But mistakes like this lead to understanding and now I know how this essential operation works and will be looking for the correct process in other functions in Houdini.

Slow and Steady. Get the Details Right First

One of the frustrations of learning at the beginning of the process is that you become impatient and want to jump ahead in the process. This is a no no. You have to go slowly and pay attention to the details. Which is why I'm taking notes on every part of the Houdini 15 learning process and checking them against the online Houdini 15 manual (which is great!). This really helps the memorization process so I can remember contexts and keyboard shortcuts, which are very important in Houdini 15.

Next Up: Continuing the Modeling Process and Learning More Advanced Functions.