Moin, Jacky,
I hope I don't sound:
- discouraging
- more arrogant than usually
- all-knowing
- nothing-knowing
- ironic
- not ironic enough
- too encouraging
- too much like a father figure
- not wise enough to give any advice at all
… but I fear even this introduction doesn't help much, so I'll try it another way.
You need to learn:
- modo
- Maya
- Max
- Blender
- Houdini
- zBrush
- Fabric Engine
- Redshift
- Octane
- VRay
- Renderman
- Renderwoman
- Arnold
- Bernold
- and a few dozen of things I forgot to mention, like Clarisse, Kurt and Python.
If you want to do it all, you need to know it all. There is no magic button “make me rich” (artists usually call this “make it awesome”, but in the end it's about “make me rich”). In no software. (here SESI marketing chimes in and whispers “except Houdini 16, of course”).
All solutions have their merits. If not, they'd be long gone. Well, SI is, even it was one of the best, but that's just proving my point.
Houdini has a background of moving points around without connecting them, while Max has a background of moving connected points around, but not too many of them or it might crash. If you want to do particles, fluids, smokes, simulations of all kinds and a bit more, start with Houdini, the more recent versions are so easy to get into that you'll forget having considered Blender in no time.
I don't relly get the point of “Houdini being bad at modelling”, because in my world it is *me* who is bad at modelling. I know some artists, who can model things even without using a computer! Many “3d artists” I know claim that modo is the best modelling application out there - and then there are those who say that anything is better than modo, but those are people who never model at all. If you want “pretty pictures”, have a look at Bryce, if you want to do walk cycles, try DAZ studio.
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Houdini has come a long way with the latest releases and the upcoming version, as far as usability, UXP, rigging, animation and even modelling are concerned.
Modelling: Houdini is not modo (as far as subD modelling goes), but it actually has a few kicks that make it *better*, even in the modelling department. It isn't zBrush and never will be, and it, so far, does not provide the most “approachable” modelling layout, but there are external (plugin-like) addons AND Houdini's modelling toolset is getting improved. Including UXP/UI. Houdini's development is rapid, and its developers are not only “listening” (like on other platform I witnessed), but actually interested and open to suggestions, that they, often enough, turn into features.
Animation in Houdini is strong, but it is a bit “hidden”. I am on a mission to help making people see that they just to have tear that blanket away to see H's power in animation. Rigging in Houdini is exctasy on … err … well … speed? Powerful, easy to grasp, flexible. It's not Messiah (yet

), but Messiah isn't as vivid, constantly evolving and getting better every single night (thanks to constant releases).
There is a FREE version of Houdini to get you started (Aprentice). There are lots and lots of tutorials out there giving you some heads ups on almost every aspect of Houdini. There are some very, very active communities, in forums and on various chat systems (IRC, Slack and something like “Dixie Klo” or so).
Rendering: Houdini both has a good renderer “on board”, but Mantra can be slow. There is support for external renderers (like Redshift), and you can, of course, export your data to Alembic or FBX to utilize other render pipelines. It depends on what you want to render … and how fast …
Scene sizes: This is something all software packages have to deal with over the coming months and years. Models are getting heavier every year and even flagships like Maya definitely have NOT kept up with requirements in production (at least in some aspects like polygon heavy geometry). Here tools like Clarisse fill a gap that even Houdini cannot, for the time being. BUT Houdini has some quite usable, stable reference/deferred loading mechanisms that, in my current experience, can be considered “better” than some other products' states.
Learning curve: People kept telling me that it's impossible to “get into Houdini without years of hard work”. I found out that this is complete utter bullshit - for me. It took me about 30-60 minutes to get familiar and comfortable with most of the navigation and fundamental UXP guidelines and a couple of weeks of 15-30 minutes a day to understand enough of the internal workings to seriously break Houdini beta versions. I personally find Houdini (15.5 and the upcoming one) one of the most approachable, most logical, easiest to understand (fundamentally) 3d applications available today. Far, far, far easier to understand than, say, modo - for a simple reason: Houdini is *consistent*. You need to understand the basic structure, how it “ticks”, then, in most cases, you can work your way around most cliffs. You may not find the *best* workflow, but that's where the community is of invaluable help. But different to other software, there (usually) isn't some jibberish that just works COMPLETELY different than all the rest.
But, again: Houdini is no silver bullet, it won't provide you with everything plus something. I do think that the recent version(s) are absolute “musts” in any generalist's toolbox. Especially at the entry price range offered for “small freelancers and/or aspiring artists” (read: people who don't really make any money from their work)

Marc