Shadow Pass Recipe
Posted on Jan 09, 2013

    Intro to Layers

    Ever notice that CG images tend to have really black shadows? The truth is, %100 black almost never occurs in real life.

    The "Shadow Pass" recipe, mentioned here is good for all compositors. Give it a try next time you're comping a shadow pass.

    Shadow Recipe

    If you were planning on multiplying the shadows at 20% opacity, try 10% instead. Then duplicate the shadow layer and change the apply mode to overlay. On this second shadow pass, apply a levels operation and clip (reduce) the whites by %50. In other words, this overlay layer will have only %50 grey or darker in it.

    That's it! Your shadows will be a rich dark color, but not overly black or muddy.

    Basic composite example

    The following example illustrates how a single CG element was hastily composited onto a photograph. This particular example was done in Photoshop, but the workflow is pretty much the same in Nuke, After Effects or any other package.

    Step 1: Clean-up the image

    The backplate (photo) was taken with an iPhone as the owner went to work. There were some obvious problems with it; Utility lines and hazard pylons just to name a few. These were edited out just to reduce the clutter of the image. Then the levels were adjusted to lighten the forground shadows a little.

    Step 2: Import CG elements

    The goal for this shot was to simply add a big bow to the building. The Giftbox Asset was used to creat a big ribbon around a box shape. A beauty pass and cast shadow pass were rendered.

    Bear in mind, that in a production setting, this "beauty pass" would itself have been a composite of about 10 layers! e.g. Diffuse Color, Specular, Ambient Occlusion, Subsurface, Reflection etc..

    Step 3: Shadows on the building

    This is just a quick exercise, so only one beauty pass, and one cast shadow pass were created. This means that the shadows inside the bow itself will not benefit from the shadow pass recipe. It will only affect the shadows cast upon the building.

    This shadow pass was rendered using a box as a stand-in for the building. This box had a shadowmatte material applied to it.

    Some shadows had to be faked. In this case the shadow of the tree branches had to be added to the bow in order to match the building.

    Step 4: Re-Apply Foreground

    The foreground fence, tree branches and utility pole, needed to be duplicated from the background, and then re-applied over the bow. This was a manual masking or roto task. The edges of this foreground layer needed to be blurred so as to not appear overly sharp and artificial.

    Step 5: Final Composite

    Here is the composited image: A gift wrapped building. Some nice touches would be to adjust the bows color levels a bit, to add a specular pass, and maybe some noise to further sell it's integration with the photograph.
    Happy Holidays!

Putting 'smart' in your Smart 3D Assets
Posted on Dec 21, 2012
    Putting 'smart' in your Smart 3D Assets.. ways to improve your assets

    In this blog we'll dig a little bit deeper and look at what makes a useful asset, and what exactly makes it 'smart'. Houdini digital assets allow the user to take their setup and wrap it into a single node. The author decides which controls will be useful and adds them to the top level. This in itself makes assets a great tool as it lets others use them without having to worry how they work.

    This touches on our first point which is asset purpose and abstraction. When creating a new asset or taking an existing setup and generating one out of it; it's useful to ask ...what is it's purpose?. Having a clear target to shoot for, makes the creation process easier and lets the author be consistent about the functionality. If the task to solve is a complex problem, break it down into smaller/simpler steps and create assets to solve these. Each asset tackles one aspect of the problem and solves it. By having individual components it helps to hide all the gory details that might be needed and abstract it into a simple concepts that a user will understand.

    As you build the asset, keep modularity and flexibility in mind. In terms of modularity the asset should contain all the needed pieces to function. This makes it easier to update later as you only need to edit single asset; instead of multiple ones. It's certainly possible to create an asset that has hundreds of controls and does multitude of jobs but when it comes to either fixing/updating, it becomes significantly more difficult. If it needs additional information try to set clear ways that the asset can get it (whether that's controls for merging additional geos, getting camera/lights/bones info, or writing out geometry to disk).

    It's a good idea to ask yourself which parts of the asset can be made procedural. Doing this during the build phase makes it easier rather than trying to procedurlize it after the fact. It will let you add specific controls and create a robust and flexible asset that has a lot of functionality. One thing to keep in mind is not to go overboard though. Houdini lets you easily add additional options and soon you might find yourself adding everything but the kitchen sink. Try to avoid the temptation :) If there's other piece of functionality that you think would be great to have, see if it's maybe a better candidate for another asset.

    It's the little things.. some additional things to keep in mind as you create your Smart 3D Assets. Grouping your controls by functionality will makes things easier to learn and use by new users. Setting proper defaults/min/max ranges will guide the users and make it easier to know what are acceptable values (if need be you can also lock the controls in Type Properties to place hard limits). Creating asset presets is a great way to show off the asset. One of the best ways to explain and demonstrate your creation is by showing it off with an example hip file. You can upload to Orbolt and the user will be able to learn from it. Describing the controls in the Help section as well as giving tips/tricks is another way to make it more useful (you 'did' write the Help docs.. right? :)

    Keeping the above in mind will help you in creating a great asset, that will be easy to use and allow you to change/update without too much hair pulling. If you have any questions or comments, feel free to contact us at

    Also, have a look at Old Schools digital asset discussions for some great info.
    Old School Blog

Anatomy of a Blackhawk 4
Posted on Jan 24, 2013

    Anatomy of a Blackhawk 4

    At this point, the basic hull, windows, and doors have been roughed in. Later we will examine the addition of extra details, surfacing and behaviors.

Anatomy of a Blackhawk 3
Posted on Jan 24, 2013

    Anatomy of a Blackhawk 3

    After creating on half of the hull, it was necessary to add windows and door openings. This was done by creating outlines and then projecting them on the hull surface.

    The results were trimmed; keeping the inside of the trim for windows and doors, and the outside for the hull.


Anatomy of a Blackhawk 2
Posted on Jan 24, 2013

    Anatomy of a Blackhawk 2

    The process of duplicating, mirroring and then joining the sides, results in a surface that is neat and orderly (all the edges meet nicely). The basic process is to model one side and mirror it. Then model the top, and mirror it. Then tweak, then join.


Anatomy of an Asset
Posted on Mar 13, 2013

    Anatomy of An Asset

    Ever wondered what goes on under the hood a digital asset? This blog takes a look at the modelling and early development of the Military Helicopter Asset

    First you need to start with some reference material. In this case photos of a plastic hobby kit were used

    These reference images were imported into the background display preferences and then used as a guide to lay down some curves.


What is this construction crew building?
Posted on Dec 21, 2012

    Reno Madness?

    What exactly is this construction crew doing? The Holiday Challenge continues! Prizes!

    See the full image, and others HERE .
    Best entries will receive an Apprentice HD subscription!

    Contest details:
    Create a holiday themed image using Houdini. Then post the results on the forum .
    Or if you prefer, you can email them directly to

    Here are some free holiday assets to get you going.

Anatomy of creating a Houdini asset.. 1..2..3.. Profit!!
Posted on Jun 19, 2019
    Houdini Assets and Orbolt

    In this blog we'll be looking at what it takes to create a standalone Houdini asset and upload it to Orbolt. We'll start with our fancy teapot model.

    This is our starting scene.

    Subnet your nodes
    If your setup has multiple objects, first part is to select all objects and collapse them into a subnet. This groups all of the objects into a single node. It makes sharing assets easy as a single node will contain everything that's needed. If you only have a single node/object you can skip this step if you wish (though you can still wrap a single node into a subnet, which future-proofs your asset as you may potentially decide to add more objects later on).

    Create Houdini Digital Asset
    Next step is to create a Houdini Digital Asset. Click with the right mouse button on the subnet node and choose Create Digital Asset. This opens a window that lets you name your asset and where to save the asset .otl file. (Operator Name is used internally by Houdini; users will see the label in the Tab menus).

    Build your asset interface
    After the initial creation the asset will have a transform and subnet folders. Since this is our custom asset we will add a control to adjust the shape of the teapot. You can drag and drop promote existing node parameters to top level controls as well as add custom parameters. To keep things organized we'll add our size control into a new folder called 'Controls'. Naming things and grouping them in the interface into logical parts makes the asset easier to use by others.

    Promote custom controls
    We'll expose the teapot size parameter by promoting it to top level. The goal is for all the controls to be at the top level of the asset so the user can quickly interact with it without having to worry about the internal setup. Drag and drop the 'Radius' on the platonic1 node onto the Controls folder in the asset Type Properties. Click Accept when done.

    Congratulations!! You now have your first Digital Asset with custom controls.

    Upload your asset to Orbolt
    One of the great things about Houdini assets is that they're a great way to share your work with others. Since everything is self contained in a single node, it's easy to give it to others. Orbolt makes this even easier by giving you a central place that assets can be uploaded and downloaded. Before we upload the asset, right mouse button click on the node and choose Match Current Definition. This will sync the asset with the latest changes (if you need to do additional changes you can always unlock it by clicking Allow Editing). Then right mouse button click on the node and choose Upload to Orbolt Asset Store.

    Houdini upload process
    The upload process makes sure that all the needed files are found and sends the file to Orblot.

    Orbolt info
    Once the file is uploaded, Orbolt upload page will open in your browser where you can fill in the details about your asset that other users can see. This is where you can show off your asset through videos/screen shots. Here you also specify the price point. It is up to you if you want to share your work with others or sell it and make some profit!!

    Hopefully this gave you a better idea about Houdini Digital Assets and Orbolt. If you have any questions or comments freel free to drop us a line at:

How to contact an a author.
Posted on Dec 07, 2012

    Got a question about an asset?

    Contact the author directly through personal messaging. Here's how...

    From the asset page, click on the authors name. This will take you to the authors page where you can find the button for personal messages.

Blog posts
Press releases