Learning Houdini Journal 18: Vehicle Tutorial - Start Over. Finish. Yeah!

Staff Writer By: Ricky Grove (gToon)


Learning Houdini Journal 18: Vehicle Tutorial - Start Over. Finish. Yeah! | Houdini, Side Effects, Procedural Modeling, Rohan Dalvi, Learning Houdini

This is the eighteenth entry of 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 17, I started a new series of tutorials created by a favorite Houdini instructor: Rohan Dalvi. The course is called "Procedural Vehicle Modeling". I completed the first chapter, but struggled with chapter two which used a Boolean technique to create doors and windows in the bus

Chapter Two - Finish Bus Front Details (Finally)

Chapter two has been a real bear for me to finish. The entire tutorial is probably too advanced for me, but I'm determined to complete the project. Most of my problems have been due to my results not being the same as Mr. Dalvi's results as he goes through the process of creating 4 details on the Bus front: the door, the cut for the tire, the front window and the grill. Conceptually, I understand the process of using Boolean technique to create the details (use a box to cut out the whole you want). Houdini, being a parametric application, uses nodes to accomplish everything. The application of nodes has been hard for me to figure out. So much so that I've started the entire first and second chapters of the tutorial twice.

Still, I think it's good to go over the steps again and again as you really start to understand what you are doing. Also, Houdini begins to become more familiar and less intimidating.

End chapter 2

-end chapter two model (front of bus)


Final Bus Front Details

The illustration above is the final bus front details (window, grill, door and tire cut). One you break it down, the modeling process is pretty strait-forward: Create a box, position it using "bbox" expression and manual manipulation, then use a cookie node to cut out the area you want on the bus model.

I noted in my previous journal that I was having problems with alignment of the boxes, but this was primarily my own issue of understanding the expressions Mr. Dalvi was using to position the box. It's just a matter of using them over and over again until you understand how certain expressions work. Also, the Houdini manual (available from within the application itself) is quite good on explaining expressions and how they are used.

boolean nodes

Three main nodes for Ch 2: Box, cookie and poly-bevel

The main problem I faced in finishing up the bus front details was using the poly-bevel node to round off the door and front window. For some reason, I kept getting a bevel that affected points instead of edges. Once I worked on the parameters outside of the tutorial (just create a box and bevel the edges), I began to understand what parameters to select in order to get the right bevel. Again, just a matter of practice.

Still Working to Understand Node-Based Workflow

I'm still struggling a bit to understand the node-based workflow of Houdini. Coming from a Cinema 4D background, it's quite a shift in world view to nodes, nodes and more nodes. I think, perhaps, it's because nodes initially separate you from the object you are working on. It's a kind of representation, whereas in a traditional 3D application you work directly on the object and adjust it's parameters. Getting this nodal mindset is essential to solving problems and fixing anything that might go wrong. Otherwise, you are lost and have to start over again. Which is what I've been doing for the last two weeks.

I'm excited about getting through chapter 2 of Rohan Dalvi's Procedural Modeling tutorial, even though it took much longer than expected. Perhaps I'll carry some of the ideas and techniques used in the first two chapters into the rest of the tutorial. I hope so, because at this rate it will be a long time before I finish!

lesson order


Next: CH 3 Bus Front - Front Door